vvEPA
United States
Environmental Protection
Agency
Hazardous Waste Engineering
Research Laboratory
Cincinnati OH 45268
EPA/600/2-86/085
September 1986
Research and Development
Geotextiles for
Drainage, Gas
Venting, and Erosion
Control at Hazardous
Waste Sites
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EPA/600/2-86/085
September 1986
GEOTEXTILES FOR DRAINAGE, GAS VENTING, AND EROSION CONTROL
AT HAZARDOUS WASTE SITES
by
Raymond C. Horz
U. S. Army Engineer Waterways Experiment Station
Vicksburg, Mississippi 39180-0631
EPA Interagency Agreement Number
AD-96-F-1-400-1
Project Officer
Janet M. Houthoofd
Land Pollution Control Division
Hazardous Waste Engineering Research Laboratory
Cincinnati, Ohio 45268
HAZARDOUS WASTE ENGINEERING RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U. S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
U.S. Environment! Protection Agency
Region V, L;^v^y
230 South Der.jbom Street
Chicago, Illinois 60604
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NOTICE
The information in this document has been funded, wholly
or in part, by the United States Environmental Protection
Agency under Interagency Agreement Number AD-96-F-1-400-1
to the U. S. Army Engineer Waterways Experiment Station.
It has been subject to the Agency's peer and administra-
tive review, and it has been approved for publication as
an EPA document.
Mention of trade names or commercial products is for
explanatory purposes only and does not imply specific
endorsement by the Environmental Protection Agency of any
product or brand in preference to others.
U,S. Environment?! Protection Agency
ii
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FOREWORD
Today's rapidly developing and changing technologies and industrial
products and practices frequently carry with them the increased generation
of solid and hazardous wastes. These materials, if improperly dealt with,
can threaten both public health and the environment. Abandoned waste sites
and accidental releases of toxic and hazardous substances to the environ^
ment also have important environmental and public health implications. The
Hazardous Waste Engineering Research Laboratory assists in providing an
authoritative and defensible engineering basis for assessing and solving
these problems. Its products support the policies, programs and regula-
tions of the Environmental Protection Agency, the permitting and other
responsibilities of State and local governments and the needs of both
large and small businesses in handling their wastes responsibly and economi-
cally.
This handbook provides general information on properties and uses
of geotextiles, and provides specific guidance for the use of geotextiles
for drainage, venting, and erosion control systems at hazardous waste
sites. This handbook is primarily intended for those involved in the
design of remedial measures for uncontrolled hazardous waste sites. It
will also serve as a source of technical information to regulatory per-
sonnel in evaluating any such designs submitted for approval
For further information, please contact the Land Pollution Control
Division of the Hazardous Waste Engineering Research Laboratory.
Thomas R. Hauser, Director
Hazardous Waste Engineering
Research Laboratory
111
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ABSTRACT
Geotextiles (engineering fabrics) have proved to be effective materials
for solving numerous drainage and stability problems in geotechnical engineer-
ing, and they can be used to solve similar problems in the containment and
disposal of solid and hazardous waste. This handbook provides general infor-
mation on geotextiles in hazardous waste landfills and provides guidance for
the designer in the use of geotextiles for drainage, venting, and erosion
control systems.
Important mechanical, hydraulic, and endurance properties of fabrics are
discussed. The most important mechanical properties are considered to be
tensile strength and elongation, tearing resistance, and puncture resistance,
as measured by the grab tensile test, trapezoidal tear test, and puncture
test, respectively. Tests for other mechanical properties such as creep
susceptibility, frictional and pull-out resistance with soil, and seam
strength are also discussed.
The important hydraulic properties of fabrics include their ability to
retain fine soil particles (piping resistance) and their ability to resist
clogging. These properties are discussed, along with the equivalent opening
size (EOS) and gradient ratio (GR) tests used to evaluate these qualities.
Possible causes of the long-term reduction of fabric hydraulic flow capacity
are discussed.
Consideration is given to fabric resistance to ultraviolet light and
chemicals and to biological degradation.
Applications of geotextiles to (1) landfill cover drains, leachate col-
lection systems, and ground-water control systems; (2) gas venting; and
(3) protection of waste covers and waste disposal sites from surface erosion
are addressed in detail. In each of these applications, design considera-
tions, fabric requirements, and construction techniques are discussed. Model
specifications for fabrics in the various applications are given. For drain-
age systems and erosion control, criteria are presented for the selection of
fabrics based on the fabric's piping resistance and clogging resistance.
Strength requirements based on the severity of the construction environment
and long-term chemical/biological degradation are addressed.
This report was submitted in fulfillment of Interagency Agreement
No. AD-96-F-1-400-1 by the U. S. Army Engineer Waterways Experiment Station
under the sponsorship of the U. S. Environmental Protection Agency. This
report covers the period October 1981 to May 1986.
IV
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CONTENTS
Chapter Page
FOREWORD iii
ABSTRACT iv
FIGURES vii
TABLES viii
ABBREVIATIONS AND SYMBOLS . , , x
1.0 INTRODUCTION ., 1-1
1.1 Purpose and Scope 1-1
1.2 Historical Background 1-1
1.3 Fabric Types and Construction 1-2
1.4 Geotextile Functions and Applications 1-13
1.5 Summary 1-18
2.0 EVALUATION OF FABRIC PROPERTIES 2-1
2 .1 General Physical Properties 2-1
2 . 2 Mechanical Properties 2-1
2. 3 Hydraulic Properties 2-15
2.4 Environmental Endurance Properties 2-23
3.0 DESIGN OF FILTERS AND DRAINAGE SYSTEMS 3-1
3.1 Requirements for Conventional (Granular) Filters.. 3-1
3.2 Requirements for Fabric Filters and Drains 3-2
3.3 Use of Fabric in Subsurface Drains 3-11
4 .0 GAS VENTING . 4-1
4.1 Introduction. • 4-1
4.2 Current Practice... 4-1
4.3 Fabric for Venting Beneath Liquid Impoundments.... 4-2
4.4 Gas Venting of Landfills 4-6
5.0 EROSION CONTROL 5-1
5 .1 Introduction 5-1
5 . 2 Fabric Selection Criteria , 5^-4
5.3 Protection of Waste Covers, Drainage Channels,
and Drainage Outlets 5-5
5.4 Streambank and Wave Protection 5-11
6.0 REFERENCES 6-1
v
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Chapter Page
7.0 BIBLIOGRAPHY 7-1
APPENDIX A: ACTIVE MARKETERS OF FABRIC, STRIP DRAINS, AND
DRAINAGE PANELS A-l
APPENDIX B: TEST METHODS AND STANDARDS B-1
APPENDIX C: GLOSSARY OF TERMS C-l
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FIGURES
Number Page
1-1 Woven Monofilament Geotextiles Having Low Percent Open Area
(Top) and High Percent Open Area (Bottom) 1-4
1-2 Woven Multifilament Geotextile 1-5
1-3 Woven Slit-Film Geotextiles 1-6
1-4 Fibrillated-Film, Woven Geotextile 1-7
1-5 Needle-Punched, Nonwoven Geotextile 1-8
1-6 Heat Bonded Nonwoven Geotextile (Top) and Resin Bonded
Nonwoven Geotextile (Bottom) 1-9
1-7 Combination Needled, Nonwoven Slit-Film Woven, Geotextile 1-10
1-8 Grids for Unidirectional Reinforcement (Top) and for
Gabions (Bottom) 1-11
1-9 Strip Drains: Alidrain Type (Top) and Geodrain (Bottom) 1-12
1-10 Drainage Panels: Enkadrain (Top) and Filtram (Bottom) 1-14
2-1 Methods of Determining Uniaxial Tensile Strength of
Geotextiles 2-2
2-2 The Grab Tensile Test 2-3
2-3 Layout of Test Apparatus for Performing Load-Extension Tests
on Fabric in Confinement 2-5
2-4 Typical Stress-Strain Curves for Geotextiles in Uniaxial
Tension 2-6
2-5 Methods for Determining Tensile Modulus of Geotextiles from
Stress-Strain Data 2-8
2-6 The Trapezoidal Tear Test Before Start of Test with Specimen
in Clamps 2-9
2-7 The Trapezoidal Tear Test with Specimen in Process of Being
Torn 2-10
2-8 Apparatuses for Determining the Coefficient of Friction and
Pullout Resistance of Fabrics and Grids 2-12
2-9 Seam Types Used in Field Seaming Geotextiles 2-13
2-10 Stitch Types Used in Field Seaming Geotextiles 2-14
2-11 Relation Between Coefficient of Permeability and Soil Type 2-19
2-12 Detail of Constant Head Permeameter Device Used for
Soil-Fabric Permeability Testing 2-20
2-13 Test Devices for Measuring the Transmissivity of Fabrics
and Meshes Under Load 2-22
3-1 Design of a Graded Filter for a Groundwater Interceptor
Trench 3-3
3-2 Interceptor and Collector Trench Configurations 3-12
3-3 General Construction Procedure for Interceptor Trench
Drains 3-13
3-4 Use of Fabric for Filtration in a Multilayered Cover
System 3-14
3-5 Prefabricated Drainage Panel Interceptor/Cutoff Trench
Drain 3-15
VII
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Number Page
3-6 Prefabricated Drainage Panel to Relieve Hydrostatic Pressure
Against Retaining Wall 3-15
3-7 Examples of Drainage Panel Collector Pipe Connections 3-17
3-8 Location of Horizontally Placed Strip Drains in Coal Refuse
Embankment . 3-18
3-9 Measured Relationships Between Time and Degree of Pore
Pressure Dissipation Within Fine Refuse Deposits with and
Without Synthetic Strip Drains 3-18
4-1 Molded Hypalon Air/Gas Vent Assembly 4-2
4-2 Half-Tube Air/Gas Vent Assembly 4-3
4-3 Use of Laminated Strips for Gas Drainage in a Geomembrane-
Lined Uranium Mine Tailings Evaporating Pond 4-5
4-4 Gas Interceptor Trench Using Geotextile to Line Trench 4-8
4-5 Gas Interceptor Trench Using Drainage Panel 4-8
5-1 Potential Soil-Erosion Resistance as a Function of Dry
Density and Atterberg Liquid Limit 5-2
5-2 Relationships Between Soil Atterberg Limits and Expected
Erosion Potential 5-3
5-3 Method of Placing Fabric for Protection of Cut and Fill
Slopes 5-10
5-4 Placement of Fabric in Swale at Windham, Connecticut,
Landfill 5-12
5-5 Use of Fabric in Construction of Runoff Collection/
Diversion Ditches 5-13
5-6 Use of Fabric to Provide Scour Protection for Culvert
Outlet 5-13
5-7 Cross Sections and Fabric Placement Detail for Use of Fabric
in Streambank Protection 5-15
5-8 Example Anchoring Treatments at Top and Toe of Fabric in Wave
Protection Structures 5-16
B-l Specimen Pattern B-6
B-2 Fabric EOS Sieving Test Apparatus B-12
B-3 Detail of Constant-Head Permeameter Test Device Used for
Gradient Ratio Testing B-14
B-4 Method of Determining U. S. Army Corps of Engineer Soil-Fabric
Gradient Ratio B-15
TABLES
Number Page
1-1 Typical Values for Some Physical Properties of Common
Polymers 1-3
1-2 Fabric Functions and Possible Applications in Hazardous
Waste Landfills 1-16
1-3 Typical Costs of Engineering Fabrics and Related Products 1-20
2-1 Typical Permeability Values for Geotextiles 2-18
2-2 Transmissivities of Fabrics and Grids Under Various Test
Conditions 2-24
2-3 Chemical Resistance of Polypropylene 2-27
2-4 Strength Retention of Polypropylene Yarns After
Exposure to Certain Chemicals 2-31
viii
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Number Page
2-5 Chemical Resistance of Polyester 2-34
2-6 Effect of Chemical Exposure on Breaking Strength and
Appearance of Synthetic Fibers 2-39
2-7 Effects of Various Chemicals on Geotextile Plastics 2-43
3-1 Recommended Criteria for Selection of Geotextiles for
Filtration/Drainage Applications 3-7
3-2 Environmental Resistance Requirements for Geotextiles 3-9
5-1 Recommended Criteria for Selection of Geotextiles for
Erosion Control Applications 5-6
B-l Published Test Methods and Standards B-2
IX
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ABBREVIATIONS AND SYMBOLS
ABBREVIATIONS
AOS — apparent opening size (see Appendix C)
ASTM — American Society for Testing and Materials
cm — centimeter(s)
CRE — constant-rate-of-extension
°C — degree(s) Centigrade (or Celsius)
°F — degree(s) Fahrenheit
EOS — equivalent opening size (see Appendix C)
ft — foot, feet
g — gram(s)
GR — gradient ratio
in. — inch(es)
kg — kilogram(s)
kN — kilonewton(s)
kPa — kilopascal(s)
Ib — pound(s)
m — meter(s)
2
m — square meter(s)
mil(s) — thousandths of an inch
mm — millimeter(s)
N — newton(s)
oz — ounce(s)
x
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ABBREVIATIONS
POA — percent open area (see Appendix C)
pcf — pounds per cubic foot
psi — pounds per square inch
sec — second(s)
2
yd — square yard (s)
SYMBOLS
A — area
C — coefficient of uniformity. C = Dfif./D
D — for a soil, the particle size of which 10 percent of the
particles, by weight, are smaller
DI — for a soil, the particle size of which 15 percent of the
particles, by weight, are smaller
D — for a soil, the particle size of which 50 percent of the
particles, by weight, are smaller
D — for a soil, the particle size of which 60 percent of the
particles, by weight, are smaller
D — for a soil, the particle size of which 85 percent of the
particles, by weight, are smaller
i — hydraulic gradient
k — coefficient of permeability (hydraulic conductivity)
k — coefficient of permeability (hydraulic conductivity) for
fabric
k — coefficient of permeability (hydraulic conductivity) in
P plane of fabric
k — coefficient of permeability (hydraulic conductivity) for
S soil
L — units of length; length between fabric grips
1 — length
XI
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SYMBOLS
L,. — length of flow path; when measuring the permeability of
fabrics, Lf is the thickness of the fabric
q — hydraulic discharge rate
T — units of time
t — thickness
W — width, specimen width
w — width
Ah — hydraulic head loss
¥ — permittivity
Q — transmissivity
XII
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1.0 INTRODUCTION
1.1 Purpose and Scope
The purpose of this technical handbook is to provide general information
on the properties and uses of geotextiles in hazardous waste landfills and to
provide specific guidance for the designer in the use of geotextiles for
drainage, gas venting, and erosion control systems. Although this handbook is
primarily intended to assist those involved in the design of remedial measures
for uncontrolled hazardous waste landfills, the design procedures and criteria
set forth here should prove equally useful to those designing controlled land
disposal facilities. This handbook is also intended to be a source of techni-
cal information to aid regulatory personnel in evaluating any such designs
submitted for approval. The user must be aware, however, that because of the
rapidly expanding technology in geotextiles, the design procedures presented
here can be expected to need modification with time. The handbook cannot
address the site-specific variables that determine whether a geotextile or
some alternative technology should be used to solve a particular problem.
Subjects discussed in this handbook include the various types of fabrics and
related products currently available, the various functions of these fabrics,
test methods for evaluating potential fabric performance, recommended design
procedures for using geotextiles and related products in drainage, gas vent-
ing, and erosion control systems, and recommended installation procedures for
the various applications.
For the purpose of this handbook, the term "geotextile" is defined as any
permeable synthetic textile product used in geotechnical engineering. Related
products such as plastic grids ("geogrids"), drainage panels, and other com-
posite products are also discussed in this handbook because these products are
used in similar applications or include geotextiles as part of their structure.
In Great Britain, the term "membrane" is used to refer to both geotex-
tiles (permeable membranes) and to impermeable plastic films whether or not
they have been reinforced with a fabric scrim. In the United States, the
generic "geomembrane" has been proposed to designate impermeable membranes
used in geotechnical engineering. Since most users of geotextiles continue to
refer to them (perhaps for phonetic and orthographic simplicity) as "engineer-
ing fabrics" or, simply, "fabrics," the terms, "engineering fabric," "fabric,"
and "geotextile" will be used interchangeably throughout this handbook.
A glossary of terms related to geotextiles appears in Appendix C.
1.2 Historical Background
Synthetic fabrics appear to have been first used in engineering construc-
tion in the United States in 1958, when a woven fabric was substituted for a
graded aggregate filter blanket in construction of a shore protection in South
Palm Beach, Florida. From that beginning, woven fabric gradually began to
1-1
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replace granular filters in coastal engineering for erosion control and for
underdrain applications. In Europe, the mid 1960's saw the introduction of
nonwoven fabrics for stabilization of roads and embankments and for erosion
protection. The first use of a nonwoven fabric in an earth dam and as a fil-
ter in a drainage trench (Giroud, 1981) took place in Europe in 1970; the
first use of a fabric in connection with a synthetic membrane took place in
1971 (Giroud, 1982) when a nonwoven fabric was used to protect a synthetic
membrane brine pond liner. The increasing use of filter fabrics by the U. S.
Army Corps of Engineers throughout the 1960's for levee slope protection and
for trench drains led to research at the U. S. Army Engineer Waterways Experi-
ment Station by Calhoun (1972) who published a report that set forth design
guidelines for projects of the U. S. Army Corps of Engineers. The mid 1970's
saw a rapid expansion in the use of both woven and nonwoven geotextiles by
government agencies as well as private firms in all types of geotechnical
engineering construction. Tremendous growth in the use of geotextiles led in
1977 to the first international conference on the use of fabrics in geotechni-
cal engineering. It was held in Paris, France. That year also saw the forma-
tion of a subcommittee on geotextiles and their applications in the American
Society for Testing and Materials (ASTM) Committee D-13 on Textile Products.
Later, this subcommittee joined with ASTM Committee D-18 on Soil and Rock to
form joint subcommittee D-13.61/18.19, which brought together the interest and
expertise of textile engineers with that of geotechnical engineers in the
development of standards for evaluating these new products. The most recent
development has been the formation in 1984 of ASTM Committee D-35 on Geotex-
tiles and Related Products. Christopher (1983a) reported that the usage of
2 2
geotextiles has grown from 12.5 million m (15 million yd ) in 1977 to
115 million m (138 million yd ) in 1983 in the United States and Canada
alone. In spite of this rapidly expanding use of geotextiles, their use and
performance in applications related to waste containment and disposal activi-
ties have only rarely been documented in the open literature.
1.3 Fabric Types and Constructions
1.3.1 Fabric Materials
Geotextiles are currently being made from polypropylene, polyester,
polyethylene, nylon, polyvinylidene chloride, and fiber glass. Some experi-
mental fabrics have been made from Kevlar. Polypropylene and polyester are
by far the most used of these materials. The physical properties of these
materials can be varied considerably, depending on the additives used in
composition and on the methods of processing into filaments and subsequent
incorporation into the finished fabric. The tensile strength of polyester and
polypropylene filaments can be increased greatly by drawing or stretching the
filaments while they are cooling from the molten state. Typical physical
property values from the most common polymers are given in Table 1-1.
Kevlar is a registered trademark of Du Pont for their aromatic polyamide
fiber.
1-2
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TABLE 1-1
TYPICAL VALUES FOR SOME PHYSICAL PROPERTIES OF COMMON
POLYMERS (Bell and Hicks et al., 1980)
Property
Specific gravity
Melting temperature, °C
(°F)
Water absorption, %
Polypropylene
0.9
175
(347)
Nil
Polyester
1.3
260
(500)
0.6
Nylon
1.1
260
(500)
2.0
Polyethylene
0.9
135
(275)
Nil
1.3.2 Fabric Construction
In woven construction, the warp yarns, which run in the direction of
manufacture and parallel with the long direction of the fabric rolls, are
interlaced with fill (or filling) yarns which run perpendicular to the long
direction of the fabric roll. This type of construction is the most expen-
sive, but it tends to produce fabrics with relatively high strengths and
moduli (ratio of tensile stress to tensile strain) and relatively low elonga-
tions at rupture. The modulus, however, depends greatly on the orientation.
When woven fabrics are pulled on a bias to the direction of the fibers, the
modulus decreases dramatically, although the ultimate breaking strength may
increase. Woven construction also produces fabric with a relatively simple
pore structure and narrow range of pore sizes or openings between fibers.
Woven fabrics are most commonly plain woven, but they are sometimes made by
twill weave or leno weave (a very open type of weave). Woven fabrics can be
composed of monofilaments (Figure 1-1) or multifilament yarns (Figure 1-2).
The monofilament woven fabrics are generally used for filter and some rein-
forcement applications. These fabrics are often passed between heated rollers
after weaving to help stabilize the positions of the filaments and regulate
the sizes of the openings in the weave, a process called calendering. The
multifilament woven fabrics are usually restricted to reinforcement applica-
tions because these fabrics are expensive but have the highest strengths of
all fabrics. A different type of monofilament is the slit film or ribbon
filament fabric (Figure 1-3). The fibers for this fabric are thin and flat
rather than round or nearly round in cross section, and they are made by
cutting sheets of plastic into narrow strips. As a result of using flat
filaments, these materials do not have uniform openings, and holes may not
exist at each crossover. These fabrics are relatively inexpensive among the
woven fabrics and are primarily used for separation (i.e., preventing the
intermixing of two materials such as aggregate and fine-grained soil).
Another special type of fabric is one made from fibrillated, slit-film fila-
ments that have been twisted to make a yarn (Figure 1-4).
The knitting process, in which yarns are looped with each other, is not
widely used in the making of geotextiles. Only two fabrics are known to
currently be made by this process: One is designed for unidirectional soil
1-3
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FIGURE 1-1
WOVEN, MONOFILAMENT GEOTEXTILES HAVING LOW-PERCENT OPEN AREA
(TOP) AND HIGH-PERCENT OPEN AREA (BOTTOM)
1-4
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FIGURE 1-2
WOVEN, MULTIFILAMENT GEOTEXTILE
*s»M«i» «8j» ,«» «!» an* «»»•» *«»•«»»«» «w «i *»» sa**?)/*^**
%«fc«^:iis« «»>«» «•>«•>«•» -«» «». *•»««•. <*» «*««*!
«p>.4MK<«w<*iii.4k>>»*;»;
«sS»w<*«r,t» «»!«««»«*»»'»«*»•«»««» ^^^» W"*^.:^ "'
^*^»^(M»h««w.«i(»<<(p.^iis»^»i«»i«i(ii>,««ifc«M.Mi^«i»ts»r«iir«»«ir««.«»«»«•»«».««< »««»*»«^«**-*»>-«^«i»^J9*i
**s^*^^^-'**«a"l»i?%«!^^ .<•*> «*•<*»•«».«»;?» *^»J*^*«*>«*,; *:,.* ..*«?*?inn*-
-*^Jf
«*>
•jjWKrp. «K •«»««»8«?«^^^» •^^'^'•'^•"•^'^J^JJg^ **5J* •** ^^^^^%»^^-^
reinforcement, and the other is for temporary surface erosion protection
With knitted fabrics, the strength properties can be varied unidirectionally
or multidirectional^. The advantages of the knitting process are that it is
less expensive than weaving and it is possible to knit tubular shapes for
surrounding drain pipes.
Nonwoven fabrics comprise those fabrics that are formed by some process
other than weaving or knitting. These fabrics can be made from either con-
tinuous filaments or from staple fibers. In either case, the fibers are laid
on a supporting screen or belt to form a mat and then bonded using one of the
processes described below. The orientation of the fibers is usually more or
less parallel with the plane of the fabric, but depending on the process, the
fibers can be randomly oriented in the plane or can be given preferential
orientation. In some processes, staple fibers can be given an orientation
perpendicular to the plane of the fabric so that the fiber ends are exposed at
the surface of the mats. In the spun-bonding process, filaments are extruded,
drawn to increase the polymer orientation (and hence strength) and laid on the
moving belt or screen as continuous filaments to form the mat, which is then
bonded by any one of the processes described below.
Needle punching. Bonding by needle punching involves pushing
many barbed needles through the fiber mat normal to the plane of
the fabric. The process causes the fibers to be mechanically
entangled. The resulting fabric has the appearance of a felt
a.
1-5
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FIGURE 1-3
WOVEN, SLIT-FILM GEOTEXTILES
It ft ft.
Illilf 111
[HfiSliMliiSTinlm
liitf'I'M HI!
1-6
-------
FIGURE 1-4
FIBRILLATED-FILM, WOVEN GEOTEXTILE
mat. The size of the needles determines the sizes of the
largest openings in the fabric, but the complex structure of the
matted filaments determines the overall permeability and pore
characteristic (see Figure 1-5). Needle-punched fabrics can be
formed by needling a single mat thickness or by needling several
mat thicknesses together.
Heat bonding. In this process, the mat is laid and then the
fibers are bonded at some or all of the points where fibers
cross one another. This can be done by incorporating fibers of
the same polymer type but having different melting points in the
mat or by using heterofilaments (i.e., fibers composed of one
type of polymer on the inside and covered or sheathed with a
polymer having a lower melting point). With heterofilament
bonding, up to 100 percent of the fiber crossover points can be
bonded, the number of bonds being controlled by the percentage
of heterofilaments in the mat. A heat-bonded fabric is shown in
Figure 1-6.
Resin bonding. Resin is introduced into the fiber mat, coating
the fibers and bonding the contacts between fibers. A resin-
bonded fabric is shown in Figure 1-6.
1-7
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FIGURE 1-5
NEEDLE-PUNCHED, NONWOVEN GEOTEXTILE
d. Combination bonding. Sometimes a combination of bonding
techniques is used to facilitate manufacture or confer desired
properties. Since needle punching tends to leave the fibers
relatively free to move with respect to each other, heat or resin
bonding can be combined with it to increase the dimensional
stability of the fabric. Very open woven fabrics are also some-
times coated to fix filament positions.
Combination fabrics are those that combine two or more of the fabrication
techniques previously described. The most common combination fabric is a
nonwoven mat that has been bonded by needle punching to a woven scrim (see
Figure 1-7). The nonwoven mat may be on one or both sides of the woven
backing.
1.3.3 Related Products
Geotextile-related products consist of grids, mats, strip drains, drain-
age panels, and fabric forms. These products are discussed here either
because they are compound products that incorporate fabric or because they are
synthetic materials used in the same ways that engineering fabrics are used.
- 1.3.3.1 Grids and Mats
Included here are the heavy construction grids or meshes of polyethylene
used mostly in soil reinforcement applications and the construction of gabions
1-8
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FIGURE 1-6
HEAT BONDED NONWOVEN GEOTEXTILE (TOP) AND RESIN BONDED
NONWOVEN GEOTEXTILE (BOTTOM)
(see Figure 1-8). The grids are drawn in the manufacturing process to orient
the molecular structure and provide high tensile strength. Another product is
a thick, open mat composed of crimped and tangled monofilament fibers that are
heat-bonded at the contacts to form a three-dimensional network particularly
suited for erosion control. Both the mat just described and certain of the
grids are also being sandwiched between conventional nonwoven fabrics to
create self-contained, subsurface drainage panels. Another special product
suited for surface erosion control, particularly during establishment of
vegetative cover, is a polypropylene open-knitted netting interlaced with
strips of paper. Still another newer product is formed as a mat of very
strong composite webbing of polyester filaments sheathed in polyethylene.
1-9
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FIGURE 1-7
COMBINATION NEEDLED, NONWOVEN AND SLIT-FILM, WOVEN
GEOTEXTILE
1.3.3.2 Strip Drains
An expanding use of fabrics is in the construction of strip drains,
initially developed to be used as vertical drains to accelerate the consoli-
dation of soft soils. Typically, the strip drains are inserted into the soil
using special equipment. Several commercial sources are available in the
United States and Canada for this technique. The actual details of fabrica-
tion of strip drains vary slightly from one manufacturer to another, but
nearly all drains consist of a continuous, channeled, plastic core that is
90 mm to 100 mm (3.5 to 4 in.) wide and surrounded by a fabric or occasionally
a heavy paper envelope. The plastic core holds the envelope open while the
channels in it provide a conduit for the movement of fluid out of the soil.
Two of the available types are shown in Figure 1-9. Strip drains are produced
in continuous rolls up to 140 m (450 ft) in length. In the typical
1-10
-------
FIGURE 1-8
GRIDS FOR UNIDIRECTIONAL REINFORCEMENT (TOP) AND FOR
GABIONS (BOTTOM)
1-11
-------
FIGURE 1-9
STRIP DRAINS: ALIDRAIN TYPE (TOP) AND GEODRAIN (BOTTOM)
1-12
-------
installation as vertical drains to accelerate consolidation as part of a
preload fill technique, the strip drain roll is mounted on the specialized
insertion equipment much like a spool of thread on a sewing machine, and the
drain is inserted within a mandrel into the soft soil to the required depth.
The drain is then cut off 0.3 m (1 ft) or so above the ground surface after
the mandrel is withdrawn, and the insertion machine is moved to the next
location to repeat the operation. Such a procedure permits economical
placement of a large number of drains over an area at close spacing (generally
0.9 to 1.8 m, or 3 to 6 ft, grid on centers). After all drains are in place
over the specified construction site area, a layer of pervious soil (sand) is
placed around and over the protruding drain ends. The area is then covered
with a sufficient thickness of additional random fill to somewhat exceed
stresses expected to be imposed by the structure to be built. After consoli-
dation (settlement) of the soft soil is sufficiently complete, the surcharge
fill is removed, and select, compacted fill is placed, if required, to bring
the site to grade.
1.3.3.3 Drainage Panels
These products constitute any of a number of proprietary products con-
sisting of a grid or mat panel sandwiched between filter fabric (Figure 1-10).
They have most commonly been used to provide drainage behind reinforced con-
crete retaining walls or to lower the ground-water table next to building
foundations. The fabrics have also been used in a horizontal orientation
beneath athletic playing fields to improve drainage. Most applications
require a perforated drain pipe to be installed at the lower edge of the
panels to collect and accelerate flow away from the area. The panels are
manufactured in a way that allows them to be overlapped to prevent soil
infiltration along the edges between panels.
1.3.3.4 Coated Fabrics
The foregoing discussion has dealt only with products that can be classi-
fied as permeable to liquids and gases. Fabrics are, however, used exten-
sively as reinforcement for impermeable synthetic membranes. These membranes
are used extensively as liners for water, wastewater, and other liquid/slurry
lagoons, and in the capping or covering of solid waste disposal sites.
Heretofore their higher cost has discouraged their use in capping operations.
Recently on the market, however, are several less expensive products that can
be considered as hybrids between fabrics and membranes. These differ from
conventional fabric-reinforced membranes in that an impermeable film of either
ethylene vinyl acetate or polyethylene is bonded to one side of a nonwoven
fabric, partially penetrating the fabric thickness. Because the bonding sys-
tems are only partially penetrating and as yet unproven, these materials may
not be suitable for liquid containment, but they could function well as
water-shedding elements in a cap or cover design. They offer greater strength
and puncture resistance than the unreinforced membranes now used most widely.
1.4 Geotextile Functions and Applications
In geotechnical and waste management engineering, geotextiles perform
one or more of five functions: filtration, drainage, reinforcement, erosion
1-13
-------
FIGURE 1-10
DRAINAGE PANELS: ENKADRAIN (TOP) AND FILTRAM (BOTTOM)
1-14
-------
control, and separation. Table 1-2 lists possible applications of geotextiles
in hazardous waste landfills, for each of the primary functions.
1.4.1 Filtration
The use of geotextiles as drain filters is probably the most widely known
and used application of geotextiles. The geotextile is used to surround a
drainage structure to prevent finer soil (or waste) from entering the drain
and reducing its flow capacity. In this function, it substitutes for the
traditional graded granular sand and gravel filter used in geotechnical engi-
neering. Both the granular filter and the geotextile filter must keep the
finer material in place while allowing water, effluent, or gas to pass without
buildup of hydrostatic pressure.
Geotextiles are commonly used as filters in leachate collection systems,
where they separate the drainage blanket from the overlying waste. They are
also often used in ground-water interceptor trenches, where they line the
trench to prevent the surrounding soil from piping and infiltrating the drain-
age material. Geotextile filters have also been used in multilayer waste
cover systems, where they are used to surround the cover's drainage layer.
One use of geotextiles as filter that differs somewhat from the uses
previously mentioned is in the construction of silt fences. These temporary
structures are intended to reduce the amount of soil lost from a construction
site and prevent contamination of water courses because of surface erosion
from storm runoff. Typical locations of silt fences are the toe of fill
slopes, the downhill side of large cut areas, and along ditches and natural
drainage areas. The silt fence serves to reduce the velocity of the running
water, allowing soil solids to settle out of suspension, and to filter the
water as it flows through the openings in the fabric.
1.4.2 Drainage
When used as a drain, a geotextile-related product acts as a conduit for
liquids or gases. These products usually substitute for gravel and perforated
pipe traditionally used in geotechnical engineering for drainage applications.
Thick, needle-punched fabrics, grids, and meshes are used to drain gases from
beneath synthetic membrane pond liners. Geotextile-related products can be
used in trench drains and blanket drains as a substitute for granular mate-
rial. Geotextile products are particularly effective on the sloping sides of
waste impoundments. If a sand drainage blanket were used as part of a leach-
ate collection system, the steepness of the impoundment sideslope would be
limited by the angle of repose of the sand, whereas a geotextile product could
be placed on any slope on which a synthetic membrane could be placed.
1.4.3 Reinforcement
Reinforcement is the process of adding mechanical strength by inclusion
of the fabric element. Geotextiles can be used in various applications to
provide tensile strength to soil, or to add support and tensile strength to a
synthetic membrane. Geotextiles are often placed beneath and on top of
synthetic membranes to act as a cushioning and load-distribution layer to
1-15
-------
TABLE 1-2
FABRIC FUNCTIONS AND POSSIBLE APPLICATIONS IN HAZARDOUS WASTE LANDFILLS
Function
Filtration
Application
Drainage
Reinforcement
• Prevent intrusion of fine particles into the
drainage layer of multilayered cover
systems while allowing water through from
above.
• Provide filter above drainage blanket in
leachate-collection systems.
• Provide filter layer in ground-water
interceptor trenches.
• Wrap collector pipes.
• Serve as silt fences.
• Provide filter layer for structure drains.
• Serve as observation well screens.
• Provide filter layer between gas transmission
layer and surrounding soil or waste.
0 Serve as drainage layer in multilayer cover
system.
• Substitute for granular material and drain
pipe in ground-water interceptor trenches.
• Provide drainage layer for structure drains.
0 Serve as transmission layer of leak-detection
system.
• Provide gas vents.
0 Provide drainage layer in leachate collection
system.
0 Accelerate consolidation of soft waste.
0 Serve as waste containment dikes on soft
soils.
(Continued)
1-16
-------
TABLE 1-2 (Continued)
Function
Reinforcement
Application
Erosion control
Separation
Form earth walls to aerate waste-holding areas
in restricted spaces.
Protect synthetic membranes from puncturing
and impact damage and provide support.
Use on construction haul roads over soft
ground.
Capping waste lagoons.
Protect landfill covers, swales, and ditches
from runoff either temporarily until vege-
tation is established, or in conjunction
with additional armoring, for permanent
protection.
Protect streambank from erosion when landfills
are adjacent to lakes and ponds.
Wave protection when landfills are adjacent to
lakes or ponds.
Prevent erosion at culvert outlets and other
outlet structures.
Use to cap waste lagoons.
Use on construction haul roads over soft
ground.
Beneath drainage layer in leachate collection
systems.
that reduces the incidence of puncturing and tearing. Fabrics are used to
reinforce the bases of dikes built on soft foundation soils, and they can be
used in the construction of retaining walls. Fabric is also used extensively
in the construction of haul roads over soft ground. Fabric is placed over the
soft ground, and graded aggregate is placed over the fabric. The aggregate
distributes the load from the wheels of vehicular traffic, and the fabric pre-
vents the aggregate from spreading and sinking into the soft ground.
1-17
-------
1.4.4 Erosion Control
In erosion control, geotextiles protect soil or vegetation against the
tractive forces of moving water. Fabrics are most commonly used in ditch
linings for erodible fine sands or cohesionless silts. The fabric lines the
ditch, and rock or gravel is placed on the fabric to secure it in place,
shield the fabric from ultraviolet light, and dissipate the energy of the
flowing water. Geotextiles are also used to provide temporary protection
against sheet erosion on newly seeded slopes. Fabric designed for the purpose
is anchored to the slope after seeding and holds the soil and seed in place
until vegetative cover is established. Most products used for this purpose
are designed to disintegrate after the vegetation has had time tc establish
itself, but at least one product is designed to remain in place permanently
and provide additional anchorage for plant roots.
1.4.5 Separation
Separation is the process of preventing two dissimilar materials from
mixing. The most common application of fabric acting as a separator is in the
capping of waste lagoons. The fabric is rolled out or otherwise spread over
the surface of the waste and covered with soil. This provides a stable work-
ing surface on which to place capping layers of either synthetic membrane or
soil. In separation applications, the ability of the fabric to pass water is
of secondary importance and may not be necessary at all. In construction of
expedient haul roads over soft soil, fabric is placed over the soft subgrade,
and gravel or crushed stone is placed on the fabric. Ir addition to providing
a reinforcing function, fabric acts as a separator, preventing the subgrade
from intruding into the overlying coarser material.
1.5 Summary
1.5.1 Advantages and Disadvantages of Geotextiles
As illustrated in the foregoing sections, geotextiles can perform many
functions in the containment and land disposal of hazardous waste. Whether a
fabric is selected to solve a particular environmental/geotechnical problem
will require the weighing of a number of factors.
Some of the advantages of fabric use are as follows:
a. A fabric provides tensile strength. In many instances, the
properties of fabrics mesh ideally with those of soil to form a
composite structure of great effectiveness.
b. Fabric can provide consistent product quality. Material
properties can be varied and controlled to a great degree to
suit a particular purpose.
c. Fabrics are widely available. They can be supplied to sites in
remote areas relatively easily, and they can often substitute
for natural materials that are simplv not available.
1-18
-------
d. In many applications, savings in time and labor costs may
justify the use of fabric even when traditional construction
materials are available at lower costs.
e. Fabric may make construction possible in areas such as soft
ground areas where construction would be nearly impossible
otherwise.
Some of the limitations of fabrics are as follows:
a. Because the use of fabrics is relatively new and unfamiliar
to many practicing engineers and contractors, knowledge of
proper design and installation practices may be lacking, leading
to improper installation and failure to perform the intended
function.
b. When used for filtration, separation, and erosion control,
fabrics lack the self-healing qualities characteristic of
granular materials traditionally used in these applications.
Extra strength may be advisable to allow for the potential for
damage during installation and environmental uncertainties after
installation.
c. The functional lifetime of fabrics is not known in the
geotechnical environment, and it is particularly unknown in the
potentially hostile chemical environment of a hazardous waste
landfill.
1.5.2 Costs
Table 1-3 provides typical 1983 cost ranges for engineering fabrics and
related products. Specific prices for a given application may be obtained
from the suppliers listed in Appendix A. The cost of fabric for a specific
project depends on current supply and demand and on such factors as the pres-
tige or significance of the particular project. Often it is often less costly
for the project as a whole to select a fabric having a higher initial cost if
the fabric has properties that expedite construction, reduce labor costs, and
reduce the chances of damage that must be repaired later.
1-19
-------
TABLE 1-3
TYPICAL COSTS OF ENGINEERING FABRICS AND RELATED PRODUCTS
i
N3
O
Type of Product
Material
Properties
Woven monofilament for filtra- Polypropylene
tion or reinforcement
Polypropylene
Woven monofilament for
reinforcement
Woven slit-film for fence
Woven slit-film for separation Polypropylene
and reinforcement
EOS 40 to 100 available
Tensile strength,
1,334 N (300 lb)c
Tensile strength,
1,334 N (300 lb)C
Woven multifilament for
reinforcement
Polypropylene Tensile strength,
445 N (100 lb)C
Tensile strength,
890 N (200 lb)C
Tensile strength,
1,334 N (500 lb)C
Tensile strength,
2,224 N (500 lb)C
Polypropylene
Price Range'
Less than More than
500 yd2 50,000 yd2
$1.40 - 1.03 $1.08 - 0.72
1.40 - 1.02 1.08 - 0.72
0.60
0.42
0.70 - 0.55 0.49 - 0.41
0.90
1.70
0.63
1.22
(Continued)
Price survey made in 1983. Prices vary according to market demand and significance of job. Price
per square yard except as noted. For conversion to metric, 1 yd2 = 0.836 m2; 500 yd2 = 418 m2;
50,000 yd2 = 41,800 m2; 1.196 x $/yd2 = $/m2.
^EOS: Equivalent Opening Size as given in U. S. Army Corps of Engineers Guide Specification CW-02215.
"ASTM D 1682 Grab Test; strength for both principal directions averaged unless otherwise noted.
-------
TABLE 1-3 (Continued)
Price
Type of Product
Woven multif ilament for uni-
directional reinforcement
Nonwoven heat-bonded for
filtration and separation
Nonwoven needled for filtra-
tion and reinforcement
Material
Properties
Polypropylene Tensile strength,
4,893 N (1,100 Ib)
(one direction only)
Polypropylene 113-179 g (4-6 oz)
EOS
Polypropylene 128
EOS
170
Less than
500 yd2
$3.
1.
75 •
01 •
- 3
- 0
.39
.69
Range
More than
50,000 yd2
$2
1
.63 -
.00 -
2.
0.
43
60
70 up
g
(4.5 oz)
0.
73
- 0
.60
0
.55 -
0.
47
variable
g
(60 oz)
0
.88
0.
69
generally 70
Nonwoven needled for filtra-
tion and reinforcement
Combination nonwoven needled
scrim for filtration
227
283
Polypropylene 340
454
Polyester 113
170
227
283
340
454
567
Polyester w/ EOS
polyester
scrim
g
g
g
g
-
g
g
(8 oz) up
(10 oz)
(12 oz)
(16 oz)
128 g (4-4.5 oz)
(6 oz)
(8 oz)
(10 oz)
g
g
g
—
(12 oz)
(16 oz)
(20 oz)
100+
1.
$1.
2.
0.
1.
1.
2.
2.
22
1
62
39
0
90
71
40
0
38
2
80
- 0
.30
- 1
- 2
.61
- 0
- 1
- 1
.60
- 1
.25
to
depending
.87
.22
.05
.80
.10
.30
.90
4.00
on
1
$1
0
1
1
2
.01 -
__
.33 -
1.
0.
.78 -
.12 -
.38 -
1.
0.
1.
97
59
0.
0.
0.
12
.26 - 1.
1.
58
72
02
63
71
91
33
and up
other
treatments and weights
(Continued)
:ASTM D 1682 Grab Test; strength for both principal directions averaged unless otherwise noted.
-------
TABLE 1-3 (Continued)
Type of Product
Material
Properties
Price
Less than
500 yd2
Range
More than
50,000 yd2
Drainage panels
Special product - permanent
surface erosion protection
Special product- temporary
erosion protection; seedbed
protection
Reinforcement grid
Varies from product to product.
Polyethylene core with thin nonwoven
fabric on both sides. EOS of panels
can vary as well as drainage capacity
and load capacity.
Nylon
Polypropylene
and paper
High-density
polyethylene
$1.38 - 0.69 $1.12 - 0.56
Thick open-mesh mat,
8.9 - 17.8 mm (0.35 in. -
0.7 in.) thick
Open knit yarn inter-
laced with paper; pro-
duct degrades after
exposure
Tensile strength 78.8 kN/m
(450 lb/in.)d
per ft'
per ft'
6.79 - 4.04 5.50 - 3.54
0.58
5.42
0.49
4.74
Separation/reinforcement grid
Drainage grid
Gabion grid
Polypropylene
Medium-density
polyethylene
High-density
polyethylene
Tensile strength,
16.1 kN/m (92 lb/in.)d
Tensile strength,
24.9 kN/m (142 Ib/in.)
Thickness: 6.4 mm
(0.25 in.)
Tensile strength,
14.9 kN/m (85 lb/in.)d
1.17
1.91
2.96
2.41
1.00
1.66
2.58
2.09
Uniaxial strip-type test; strength for stronger principal direction only.
-------
2.0 EVALUATION OF FABRIC PROPERTIES
2.1 General Physical Properties
Geotextiles were developed from conventional textile technology and much
of the way of thinking of geotextiles and evaluating them, particularly by
manufacturers and marketers in the early days of geotextile use, came from
textile industry practice. Such general physical properties as fiber composi-
tion, fabric construction, weight per unit area, thickness, and fiber diameter
are still useful in describing fabrics and for identification purposes. Also,
some of the general physical properties of fabrics can have very practical
uses. For example, the width and length of fabric rolls can be of practical
importance to a contractor in judging how best to handle the fabric for
installation. Also, knowledge of the specific gravity of a fiber making up a
fabric can be useful because in some applications the fabric must be able to
sink in water and in other applications the fabric must float. The specific
gravity of the fiber tells the prospective user which the fabric is likely to
do. Water absorption can also be important since a fabric that readily
absorbs water can become difficult to work when placed on wet ground. Whereas
a fabric that is hydrophobic is much more easily worked in these circum-
stances. Though the information discussed above is useful for evaluating
fabrics for many engineering applications, the more significant properties
from an engineering standpoint are the mechanical, hydraulic, and environ-
mental endurance properties discussed in the following sections.
2.2 Mechanical Properties
The mechanical properties of engineering fabrics include tensile
strength, tensile stress-strain relationship (or modulus), puncture and burst
resistance, penetration resistance, creep resistance, abrasion resistance,
tear resistance, flexibility, soil-fabric sliding resistance, and fatigue
resistance. These qualities are most important to reinforcement applications
of geotextiles and to the survivability of the fabric during installation.
Ease of Installation is also affected by such qualities as flexibility.
2.2.1 Tensile Strength
The first comprehensive effort to evaluate fabrics for engineering pur-
poses was made by Calhoun and reported in 1972. In his studies, he adapted
test methods already in use in the textile industry. For tensile strength
o
this was the test described in ASTM D 1682. Three methods are described in
this ASTM standard: the cut strip test, the ravelled strip test, and the grab
test. The test configurations for the ravelled strip and the grab tensile
test are illustrated in Figure 2-1. All of the these tests are uniaxial
tensile tests in which stress is applied to the fabric in one direction only.
See Appendix B for a list of all ASTM test methods mentioned in this handbook.
2-1
-------
FIGURE 2-1
METHODS OF DETERMINING UNIAXIAL TENSILE STRENGTH OF GEOTEXTILES
FABRIC
SPECIMEN
TEST
GRIPS +¥
I
50mm
DIRECTION
OF PULL
TEST
GRIP
- FABRIC
SPECIMEN •
ASTM GRAB
TENSILE TEST
ASTM STRIP TENSILE
TEST (2-INCH RAVELED
STRIP ILLUSTRATED)
I
200mm
ASTM PROPOSED WIDE -
WIDTH TENSILE TEST,W/L= 2
-------
These tests were developed for rapid quality control purposes in the textile
industry and have several potential disadvantages when applied to geotextiles.
The method used by Calhoun and cited in most strength specifications for
geotextiles is the grab test method. The test uses a 100- by 200-mm (4- by
8-in.) fabric specimen that is pulled by a set of grips spaced 75 mm (3 in.)
apart (see Figure 2-2). Grips 25-mm (1 in.) square have been used most com-
monly in the past, although 25-mm by 50-mm (1-in. by 2-in.) grips are also
FIGURE 2-2
THE GRAB TENSILE TEST
allowed by the method and are now the preferred size. The grab test method is
a valuable test because of its simplicity and because it simulates the type of
localized stressing that often occurs in actual installations. Nevertheless,
the test has several limitations. First, it is impossible to evaluate the
strength of the fabric that is directly between the grips because of the
strength contribution of the surrounding fabric. When a fabric is used in
reinforcement applications where the strength per unit width of the fabric
must be known, this method tends to overstate the fabric strength. The second
limitation of the test is that while it evaluates the strength in uniaxial
tension, in most applications a fabric is actually undergoing either biaxial
(plane-strain) or triaxial stressing. This is an important limitation, since
the strength—and especially the stress-strain properties of nonwoven fabrics
and to a lesser degree woven fabrics—differ radically depending on whether
the fabric is undergoing one-, two-, or three-dimensional stressing. For
example, in most cases when a fabric is placed in tension in a reinforcing
application, it is surrounded by the confining pressure of soil creating
interfiber friction that acts to inhibit the movement of fibers relative to
each other. There have been several attempts to simulate more closely the
2-3
-------
stress state of fabrics in the field. Some attempts have been restricted to
the biaxial stress state where the fabric is pulled simultaneously in two
directions or where the lateral straining of the fabric has been prevented or
minimized. Most of the test methods that have been tried have proved to be
too complex for practical application (Sissons, 1977; Viergever et al., 1977).
The most ambitious attempt to simulate actual field tensile stress conditions
in the laboratory has been by McGown and Andrawes (1982). In this test,
fabric specimens are tested in tension while actually confined in soil at var-
ious pressures (see Figure 2-3). The results of tests performed in this ap-
paratus have demonstrated that the stress-strain properties of fabrics con-
fined in soil can be radically different from the properties of fabrics tested
in an unconfined state.
An attempt to develop a compromise test that would provide more realistic
strength and modulus properties than those provided by the conventional grab
and strip tensile tests has led to the development of the so-called wide-width
tensile test. This is a uniaxial strip tensile test in which the fabric
specimen is much wider than the distance between the gripping jaws. This con-
figuration tends to minimize the effect of the lateral contraction of the
outer portion of the fabric specimen on the strength and modulus values of the
fabric. Work done by the French Geotextiles Committee has led to their speci-
fying a ratio of 1 to 5 for the ratio of distance between the grips to the
width of the specimen (LeFlaive et al. 1982). ASTM is currently developing a
wide-width tensile test having a 1 to 2 ratio gage length (the distance
between the grips) to specimen-width. This has been accepted as a reasonable
compromise, as research by Shrestha and Bell (1982a) and McGown et al. (1982)
has shown that a gage-length-to-width ratio of 1 to 2 provides reasonable
results for both woven and nonwoven fabrics.
A third limitation of standard tensile testing methods is that it is
designed for quality control purposes where speed of test results is impor-
tant, thus the rate of testing specified is much too high to simulate the rate
of straining in geotechnical applications. Several investigations (Shrestha
and Bell, 1982a; Haliburton et al., 1978) have experimented with a reduced
test rate that is from the commonly used 305 mm (12 in./min) which is equal to
400 percent strain/min to a rate of 0.5 to 10 percent strain/min. A compro-
mise testing rate that considers both testing time and cost, and the cost and
rate of straining typical of geotechnical field situations has resulted in a
recommended rate of 10 percent/min for the proposed ASTM standard wide-width
tensile test.
2.2.2 Tensile Modulus
Tensile strength alone does not tell the whole story about the strength
behavior of a fabric under load. Of significant importance is the tensile
modulus or the way in which the fabric resists straining. Figure 2-4 gives
typical stress-strain curves for engineering fabrics in uniaxial tension. As
can be seen from the figure, different fabric constructions lead to vastly
different stress-strain properties. No one stress-strain curve shape is
desirable for all applications. For reinforcement applications, generally a
curve in which the stress builds up rapidly with very little strain is most
desirable. In erosion control or drainage and filtration applications,
2-4
-------
FIGURE 2-3
LAYOUT OF TEST APPARATUS FOR PERFORMING LOAD-EXTENSION TESTS ON FABRIC IN
CONFINEMENT (McGown and Andrawes, 1982)
160 mm
NJ
I
Pressure
bellows
Geotextile
specimen
2OO x 100 mm
1
325
Pressure
bellows
mm
Confining
soil
Geotextile
specimen
200x100 mm
1
?
/
j
'>',
\
^
t*
/
' /
I
/
/
/
/
P^
9^^
V^l
/
1
/
/
/
/
/
y
',
/
/
>
/
. /
/
/
/
7
/
_ Thickness of sand
on eoch side = 6 mm
-------
FIGURE 2-4
TYPICAL STRESS-STRAIN CURVES FOR GEOTEXTILES IN UNIAXIAL TENSION
(Haliburton et al., 1981)
CURVE
A -
B -
C -
D -
FABRIC TYPE
MULTI-FILAMENT WOVEN
NEEDLE-PUNCH NONWOVEN
HEAT-BONDED NONWOVEN
MONOFILAMENT WOVEN
00
LJJ
cc
LLJ
Z
LU
I-
o
cc
00
CURVE A
CURVE D
CURVE B
FABRIC TENSILE STRAIN
2-f
-------
however, where the fabric may be struck by rocks or have to conform to irregu-
lar surfaces, a stress-strain curve such as illustrated by curve B would be
much more desirable. Figure 2-5 illustrates three methods of determining the
tensile modulus of engineering fabrics from stress-strain data. The figure
illustrates how the modulus will vary depending on the method used for deter-
mining it. For reinforcement applications, a secant modulus at a strain of
about 10 percent has been used commonly (Haliburton et al., 1981). Just as
for tensile strength, the rate of testing is important in evaluating the modu-
lus of a fabric.
2.2.3 Puncture and Burst Resistance
Bell et al. (1980) point out that there are several mechanisms that can
cause localized fabric failure, and resistance to these mechanisms can be
classified as:
a. Burst resistance: The resistance of fabric to rupture from
pressure applied normal to the plane of the fabric (bursting
results from fabric tensile failure). This type of failure is
likely to occur, for example, where a fabric supports an
impermeable membrane across a crack or depression in the soil or
rigid substratum.
b. Puncture resistance: The resistance of a fabric to failure from
a load applied over a relatively small area by a blunt object
with failure resulting from fiber tensile failure. This type of
failure is closely related to bursting failure in that the basic
tensile strength and elongation characteristics of the fabric
are the major determining factors in resistance.
c. Penetration resistance: The resistance of the fabric to penetra-
tion by a sharp, pointed object with initial penetration result-
ing in fiber separation and further penetration causing a tear-
ing of the fabric.
d. Cutting resistance: The resistance of the fabric or fabric
fiber to cutting (actually shear failure) when struck between
two hard objects. An example of this type of failure occurs
when fabric is resting on a rock and another rock is dropped on
the fabric.
The tests for burst and puncture resistance used in the United States are
described in ASTM D 3786, "Hydraulic Bursting Strength of Knitted Goods and
Nonwoven Fabrics: Diaphram Bursting Strength Tester Method," and D 3787
"Bursting Strength of Knitted Goods: Constant-Rate-of-Traverse (CRT), Ball
Burst Test." The former method applies an increasing hydrostatic pressure
against a fabric held in a 32-mm (1-1/4-in.) inside diameter ring clamp, and
the pressure required to fail the specimen is reported as the bursting pres-
sure in kPa or lb/in.2. The latter method uses a ring clamp having a 44-mm
(1-3/4-in.) inside diameter. The unmodified test method specifies that a
25-mm (1-in.) diameter polished steel ball be pushed against the specimen
until a burst is produced. Calhoun (1972) modified this procedure by
2-7
-------
FIGURE 2-5
I
00
METHODS FOR DETERMINING TENSILE MODULUS OF GEOTEXTILES FROM STRESS-STRAIN DATA
(Haliburton et al., 1981)
MODULUS (F/L)
/
/
AsTRESS-
STRAIN
CURVE
STRAIN (L/L)
c/)
en
111
cr
OFFSET//
MODULUS (F/L)
STRESS-
STRAIN
CURVE
STRAIN (L/L)
u_
CO
ILI
OC
I-
co
MODULUS (F/L.
STRESS-
STRAIN
CURVE
DESIRED
STRAIN
STRAIN (L/L)
A. INITIAL TANGENT
MODULUS
B. OFFSET TANGENT
MODULUS
C. SECANT MODULUS
AT DESIRED STRAIN
-------
replacing the 25-mm (1.0-in.) diameter ball with an 8-mm (5/16-in.) diameter
rod that was pushed through the fabric specimen. The U.S. Army Corps of Engi-
neers has modified this test further by incorporating a hemispherical tip on
the rod (Department of the Army, 1977).
2.2.4 Tear Resistance
Once a break has formed in a fabric, tear resistance is the measure of
the force required to propagate the break. From field observation, it can be
concluded that the tear resistance of a fabric is, for most applications, more
important than puncture resistance. Two types of tear tests are currently
available for evaluating fabrics—the tongue tear test described in ASTM
D 2262 and the trapezoidal tear test described as one of the test procedures
in ASTM D 1117. The trapezoidal tear test is currently being considered by
ASTM Committee D35 on Geotextiles for adoption as the method of evaluating the
tearing resistance of geotextiles. The name of the method comes from the
shape of the specimen used in the test. The specimen is trimmed in the shape
of a trapezoid with a cut made in the center of the shortest side. The speci-
men is then clamped in a testing machine and the force required to propagate
the cut is reported as the tearing strength. Figure 2-6 shows a test specimen
about to be tested, and Figure 2-7 shows the response of the specimen during
the test.
FIGURE 2-6
THE TRAPEZOIDAL TEAR TEST BEFORE START OF TEST
WITH SPECIMEN IN CLAMPS
2-9
-------
FIGURE 2-7
THE TRAPEZOIDAL TEAR TEST WITH SPECIMEN IN
PROCESS OF BEING TORN
2.2.5 Creep Resistance
Creep resistance is an important quality for applications where a fabric
must withstand loads for very long periods of time. Research indicates (Allen
et al., 1982) that in general, polypropylenes show more creep susceptibility
than polyesters, and McGown et al. (1982) has shown that fabrics, when con-
fined in soil, have less creep susceptibility than when tested in isolation.
However, all fabrics will creep when subjected to a high enough stress level.
Creep testing is used to establish a safe level of stress for the particular
application. As yet, there is no standardized test for evaluating the creep
susceptibility of fabrics. However, a tensile test in which a constant load
was placed on the fabric and the amount of deformation measured over time was
used to evaluate fabrics for the reinforcement of the foundation of an embank-
ment at Pinto Pass, Alabama (Haliburton et al., 1978). In this series of
tests, a 25-mm (1-in.) wide strip of woven fabric was loaded with dead
weights; a dial gage was used to measure the amount of deformation that took
place with time. Shrestha and Bell (1982b) performed similar shorter term
tests in which they used a wide-width-type tensile apparatus to apply load to
the specimen.
2-10
-------
2.2.6 Abrasion Resistance
Abrasion resistance is the ability of a fabric to resist wear by fric-
tion. Abrasion resistance is a necessary quality in slope protection appli-
cations where wave wash or water currents may cause repeated movements of
stone or block protection elements against a fabric. Abrasion resistance is
of major importance in railroad track rehabilitation where fabric is used to
separate ballast from the underlying subgrade and provide drainage for the
ballast. The only standardized test for abrasion resistance used to date is
ASTM D 3884, Abrasion Resistance of Textile Fabrics (Rotary Platform, Double
Head Method), formerly denoted as D 1175. The test consists of a fabric
specimen being rotated on a platform while a pair of abrasive wheels roll in a
circular track over the specimen. The rate of abrasion varies according to
the type of abrasive wheel used, the number of revolutions to which the speci-
men is subjected, and the weight applied to each wheel. In the typical test,
rubber-based abrasive wheels are used, and the specimen is rotated for
1000 revolutions with a 1-kg (2.2-lb) load applied to each of the two wheels.
If the fabric specimen is intact after being abraded, a cut strip tensile test
specimen is prepared from the abraded fabric and the residual breaking
strength is determined. This test was developed by the textile industry to
evaluate apparel fabrics and several investigators claim that it does not cor-
relate well with actual fabric performance, at least not in railroad applica-
tions. Presently, no other standardized tests exist for evaluating the abra-
sion resistance of geotextiles, and the method continues to be used where
abrasion resistance must be evaluated.
2.2.7 Soil-Fabric Friction
The frictional resistance between soil and fabric is of vital importance
in virtually all reinforcement applications. Soil-fabric friction usually
provides the sole means by which tensile forces in fabric are transferred to
the soil. There are three types of tests for evaluating the coefficient of
friction between soil and fabric, as shown in Figure 2-8. The device shown in
Figure 2-8a is the simplest and provides valid values for the friction between
granular, free-draining soil and fabrics. The device shown in Figure 2-8b
differs from that shown in Figure 2-8a in that soil is present on both sides
of the fabric. When evaluating the friction between fabric and cohesive soils
or soils of low permeability, it may be desirable to use the latter apparatus
as the presence of soil on both sides of the fabric more closely simulates the
restricted drainage that may exist in the actual field installation.
The pullout test shown in Figure 2~8c is the only appropriate way of
evaluating the frictional interaction between reinforcement materials such as
grids where soil is present in the spaces between the reinforcement members.
A direct shear-type test applied to this type of material would measure the
shear resistance of the soil present in the spaces between the reinforcement
elements without indicating how well the reinforcement was anchored in the
soil. As yet, no standardized procedures exist for evaluating soil-fabric
friction and pullout resistance.
2-11
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FIGURE 2-8
APPARATUSES FOR DETERMINING THE COEFFICIENT OF FRICTION AND PULLOUT
RESISTANCE OF FABRICS AND GRIDS
FABRIC
CLAMP
NORMAL
LOAD
•.-'•:-SOIL--' : ••'.: -
SHEAR FORCE
RIGID BASE
(a) DIRECT SHEAR TEST SOIL-FABRIC
NORMAL
LOAD
FABRIC
CLAMP
..;•.r:; sp!L;.••••".".••;•]
_.:-:.";;; SOIL;:': ;.': | :V.::
SHEAR FORCE
FLOATING LOWER
CONFINING FRAME
(b) DIRECT SHEAR TEST-SOIL-FABRIC-SOIL
NORMAL
LOAD
.: : -SOIL.- •. :.:••••
L\\\\\\\\1
FLOATING CONFINING
FRAMES (REQ'D FOR
COHESIVE SOILS ONLY)
SHEAR FORCE
(c) PULLOUT TEST
2-12
-------
In addition to soil-fabric friction, fabric-fabric and fabric-membrane
frictions may be of interest in certain special situations. The same princi-
ples illustrated in Figure 2-8 can be applied to evaluate these properties.
2.2.8 Seam Strength
Fabric panels can be joined by overlapping, stapling, heat welding, or
sewing. Simple overlapping and staking or nailing to the underlying soil may
be all that is necessary where the primary purpose is to hold the fabric in
place during installation. However, where the seam between two fabric sheets
must withstand tensile stress or where the security of the seam is of prime
importance, sewing has proved to be the most reliable method of joining fabric
panels. Stronger and more durable seams can usually be produced in a manufac-
turing or fabricating plant than can be produced in the field. 'The types of
sewn seams that can be produced in the field by portable sewing machines at
present are limited to those shown in Figure 2-9. The designations of the
seams correspond to the designations in Federal Standard 751a. Provided the
fabric is selvedged, the double-sewn seam SSa-2 is the preferred method of
seaming. However, where the edges of the fabric are subject to unraveling,
SSd or SSn seams are preferred. Currently marketed, the portable sewing
machines that can be used to sew seams in geotextiles were originally designed
FIGURE 2-9
SEAM TYPES USED IN FIELD SEAMING GEOTEXTILES
SSa-l
SSa-2
SSd-
SSd-2
SSn- I
SSn-2
2-13
-------
as bag closing machines. These machines produce either a single- or double-
thread chain stitch as shown in Figure 2-10. Both of these stitches are
subject to unraveling, but the single-thread stitch is much more susceptible
and must be tied off at the end of each stitching. Two rows of stitches are
preferred wherever possible for all field seaming.
FIGURE 2-10
STITCH TYPES USED IN FIELD SEAMING OF GEOTEXTILES
DIRECTION OF SUCCESSIVE STITCH FORMATION
/ 9 J t'J *) J!^
y^^ ff f f "T^
STITCH TYPE 101, ONE-THREAD CHAIN STITCH
DIRECTION OF SUCCESSIVE STITCH FORMATION
r~\^ \ Q, /j FF f
ft fi i ftrrrrf^ XNTTTI ill? 11T3TS> jQ-^ t f i i I
STITCH TYPE 401, TWO-THREAD CHAIN STITCH
The strength of seams should be evaluated using the same strength test
used to evaluate the fabric. For example, if the grab test (ASTM D 1682) is
used to evaluate the fabric, the grab test (as described in ASTM D 1683)
should be used to evaluate the seam. On the other hand, if the wide-width
tensile test is used to test the fabric, then it should be used to evaluate
the seam.
Seam strength requirements have often been specified as a percentage of
the strength of the fabric. In most cases however, the seam strength
2-14
-------
requirement should be specified to be the same as the fabric strength require-
ment. Thus if a 334 N grab strength is required of the fabric, a 334 N grab
strength should be required of the seam. When using any test procedure, care
must be taken to assure that the seam does not fail by unraveling rather than
breaking of the fabric or threads.
2.2.9 Flexibility
Flexibility is the property of a fabric that enables it to conform to
irregular surfaces. In the apparel industry, this property is called drape.
High flexibility may be either desirable or undesirable, depending on the
application. In drainage and erosion control applications, high flexibility
is desirable, as it enables the fabric to attain intimate contact with the
soil, which it must retain. On the other hand, when used to cap a waste
lagoon or form a haul road over soft ground, a fabric of low flexibility may
make the work considerably easier by enabling workmen to walk on the fabric
while placing it without sinking into the underlying soft soil or waste
material. ASTM D 1388 (Option A) is a test to measure flexibility of fabrics.
This procedure has been modified slightly by Haliburton et al. (1981) to make
it more suitable for the stiffer engineering fabrics. Fabrics with low
flexibility (high stiffness) can increase the cost effectiveness of a fabric
installation when hand-labor-intensive fabric placement operations control the
rate of job progress.
2.2.10 Fatigue
Fatigue is defined as the failure of fabric after repeated application
and release of load. Fatigue only appears to be a problem in railroad track
rehabilitation and will not be discussed further.
2.3 Hydraulic Properties
The hydraulic properties of fabrics are those that govern the ability of
the fabric to pass liquids (and gases) and retain solid particles. The
properties encompass piping resistance (related to the fabric pore sizes),
permeability (the ease with which water or gas can pass through the fabric),
and clogging resistance (the ability to resist reduction in permeability with
time).
2.3.1 Piping Resistance
Piping resistance is the ability of a fabric to retain solid particles
and is related to the sizes and complexity of the pores or openings in the
fabric. Numerous approaches have been taken to measuring the sizes of open-
ings in fabric filters. These have ranged from microscopic examination of
thin sections of fabric encased in resin (Masounave et al., 1980), and
measurement of the pressure required to cause the bubbling of air through the
fabric when submerged in water (British Standards Institute, 1963), to the
measurement of the quantity of sand or glass be>ads of various sizes that can
be shaken through the fabric (Calhoun, 1972; Ogink, 1975; Ruddock, 1977).
None of the methods has proven entirely satisfactory; however, some variation
2-15
-------
of the methods using narrowly-sized sand grains or glass beads (sometimes
called ballotini) is by far the most widely used.
In the United States, a test of this sort was first developed by Calhoun
(1972), primarily for the evaluation of woven fabrics. In his test procedure,
sized, rounded sand grains were shaken over samples of woven fabric for
20 min, and the size of sand of which less than 5 percent passed after shaking
was taken as the equivalent opening size (EOS) of the fabric. This procedure
was then adopted by the U. S. Army Corps of Engineers for evaluating the open-
ing sizes of fabrics. Calhoun's procedure was later modified by adopting
glass beads instead of rounded sand and reducing the quantity of material
placed on the fabric specimen from 150 to 50 g (5.3 to 1.8 oz). The adoption
of glass beads was an attempt to reduce the test variability by eliminating
the possible variations between sand samples.
Variables that affect the results of the sieving methods are: (1) siev-
ing time, (2) quantity of particles placed on the fabric sample, (3) the use
of beads versus sand, (4) atmospheric humidity, (5) the use of antistatic
devices, and (6) the criteria for selection of opening size from the results
of the sewing operation.
The EOS is the size of sand or beads of which fewer than 5 percent pass
the fabric sample. Other sieving procedures use other percentages (such as 10
or 50 percent) as the sizing percentage. The EOS test should properly refer
only to the test in which the percentage passing is 5 percent.
Manufacturers of needle-punched fabrics have objected to the EOS test for
having a very low degree of reproducibility for fabrics of this type. Never-
theless, the EOS as described in the U. S. Army Corps of Engineers Guide
Specification CW-02215 remains the only broadly accepted method in the United
States for evaluating the pore sizes of fabrics. ASTM Committee D35 on Geo-
textiles is currently working on a standard for determining the opening size
of geotextiles that is very similar to the EOS test. The test will be called
the apparent opening size (AOS) test.
Note that when any design criterion are used for fabric piping resis-
tance, the method by which the fabric pore size is measured will affect the
fabric selected; thus any design criterion must specify the test method by
which the fabric pore size is to be evaluated.
2.3.2 Permeability
When engineering fabrics are used in filtration and drainage applica-
tions, they must, after installation, have a flow capacity adequate to prevent
significant hydrostatic pressure buildup in the soil being drained and must be
able to maintain that flow capacity for the range of flow conditions that will
exist for that particular installation. For soils, the indicator of flow
capacity is the coefficient of permeability as defined by Darcy's law. This
can be extended to engineering fabrics as follows:
q = kiA = k(Ah/Lf)A Equation 2-1
2-16
-------
where
3
q = hydraulic discharge rate, L /T
k = Darcy coefficient of permeability, L/T
i = hydraulic gradient, L/L
2
A = total cross-sectional area available to flow, L
Ah = hydraulic head loss through the fabric, L
L = length of flow path (fabric thickness) over which Ah occurs, L
The proper application of this equation requires that fabric thickness be
considered. However, since the ease of flow through a fabric, regardless of
its thickness, is the property of primary interest, Equation 2-1 can be
modified to define a property permittivity, Y, as follows:
Numerous attempts have been made to measure the permeabilities and permittivi-
ties of engineering fabrics. The limitation of most such attempts is that
Darcy's law applies only so long as flow through the fabric remains laminar.
Unfortunately, this is very difficult to achieve for fabrics, since the
hydraulic heads required to assure laminar flow are so small as to be
difficult to measure accurately unless many layers of fabric are stacked
together to increase the flow path through the fabric with the latter method,
the procedure is more complex, and uncertainty exists as to the interaction of
the layers with each other. Despite the fact that Darcy's equation does not
apply for most measurements of fabric permeability, the values obtained from
such measurements are sometimes considered useful as a relative measure of the
permeabilities and permittivities of various fabrics. Table 2-1 lists the
results of one such set of tests. As shown by comparison with Figure 2-11,
the permeabilities of engineering fabrics exceed the permeabilities of most
sands and finer grained soils.
2.3.3 Clogging Resistance
Clogging is the reduction in permeability or permittivity of a fabric
resulting from blocking of the pores of the fabric by either soil particles or
bacterial or chemical encrustations being deposited on or in the fabric. To
some degree clogging takes place with all fabrics in contact with soil, and
this is why permeabilities of fabrics measured in isolation are of only
limited usefulness. However, in normal soil-fabric filtering systems, numer-
ous investigations (Calhoun, 1972; Schober and Teindl, 1979; Haliburton and
Wood, 1982; Chen et al., 1981) have shown that for detrimental clogging to
occur because of the soil itself, there must be a migration of fine soil
particles through the soil matrix to the surface of the fabric. For most
2-17
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TABLE 2-1
TYPICAL PERMEABILITY VALUES FOR GEOTEXTILES&
Coefficient
NW1
2
3
4
5
Wl
W2
W3
Cl
Type
Resin-bonded staple, nonwoven
Heat-bonded filament, nonwoven
Heat-bonded filament, nonwoven
Needle-punched filament,
nonwoven
Needle-punched filament,
nonwoven
Multif ilament , woven
Monof ilament, woven
Slit-film, woven
Slit-film, woven with needle
punched rap
Fabric of Perme-. _ . . . .
Thickness ability, k^ Pemuttivity. *
mm cm/ sec sec
0.86
0.74
0.38
3.00
5.16
0.51
0.41
0.56
0.97
1.2
7.8
1.3
3.4
3.8
2.0
1.8
2.0
1.0
x 10"1
x 10~2
x 10~2
x 10"1
x 10"1
x 10~3
x 10~2
x 10~3
x 10~2
140
110
34
110
74
4
45
3
11
*Blair et al., 1981.
Tests were performed using falling head test apparatus with head drop from
30 to 10 cm. Turbulent flow assumed; no compression of fabric.
natural soils, internal migration will not take place. However, internal
migration may take place under sufficient gradient if one of the following
conditions exists:
(1) The soil is very widely graded, having a coefficient of
uniformity C greater than 20 (Sherard, 1979).
(2) The soil is gap graded.
(3) The soil against the fabric is repeatedly disturbed and goes into
suspension in water so that fines are allowed to migrate to the
soil/fabric interface.
Calhoun (1972) developed a device for measuring soil-fabric permeability
and evaluating the extent to which clogging would take place for a given
2-18
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FIGURE 2-11
RELATION BETWEEN COEFFICIENT OF PERMEABILITY AND SOIL TYPE
(Cedergren, 1977a)
1x10 1x10 1x10
JxlO"" 1x10 " 0.001 0.01
Coefficient of permeability, cm/sec
soil-fabric combination. Figure 2-12 illustrates the type of device used for
this purpose. After performing extensive tests using the apparatus, Calhoun
concluded that if the percentage open area for woven fabric (i.e., the ratio
of the area of the openings in the fabric to the total area of the fabric
specimen, expressed as a percentage) was sufficiently large, the fabric would
be resistant to clogging because of internal migration of fines. This concept
proved to be useful at the time, but it was restricted to woven fabrics having
distinct, easily measured openings. Later, the U. S. Army Corps of Engineers
developed the concept of the gradient ratio—-the ratio of the hydraulic
gradient across the fabric and the 25 mm (1 in.) of soil immediately above the
fabric to the hydraulic gradient between 25 and 75 mm (1 and 3 in.) above the
fabric. Accordingly, from Figure 2-12, the gradient ratio is
GR
H2+H3
Whenever a soil is suspected of being internally unstable, as in cases (1) and
(2) above, the particular soil-fabric combination can be evaluated by means of
2-19
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FIGURE 2-12
DETAIL OF CONSTANT HEAD PERMEAMETER DEVICE USED FOR
SOIL-FABRIC PERMEABILITY TESTING
3
INLET FROM CONSTANT
HEAD RESERVOIR
DISCHARGE
BLEED
4 IN DIA
OR LARGER
LUCITE
CYLINDER —
\
L3=25 MM
:SOIL:
L2=25 MM
L =25 MM _
GEOTEXTILE
L=IOO MM
MINIMUM
SHUT OFF VALVE
•STANDPIPE
(NOT TO SCALE)
CORPS OF ENGINEER-TYPE GRADIENT
RATIO TEST DEVICE
the soil-fabric test apparatus and the gradient ratio. The third case
involves proper construction technique to assure that the engineering fabric
is maintained in intimate contact with the soil.
2.3.4 In-Plane Permeability
A great deal of experimentation has recently been devoted to the measure-
ment of the permeability or flow capacity in the plane of fabrics and related
products. The ability of certain fabrics and products such as drainage grids,
meshes, and panels to transmit significant quantities of fluids in the plane
of their structure offers one of the greatest potential uses of these mate-
rials in the waste management area. The permeability of relatively thin
planar materials parallel to their plane can be expressed by Darcy's law in
the same way as flow perpendicular to the plane. However, just as with flow
across the plane of a fabric, flow capacity in the plane is best expressed
independently of the fabric thickness. The reason is that the thickness of
the various materials may differ considerably whereas the ability to transmit
2-20
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fluid under a given head or driving force is the property of interest. The
property of in-plane flow capacity of a fabric is termed "transmissivity," 8,
and it is derived from Darcy's law as shown below.
q = kpiA
k Ahwt
q = kp(Ah/l)(wt)
k t = G = -*-,— Equation 2-3
p Ahw
where
3 -1
q = hydraulic discharge rate, L T
k = in-plane coefficient of permeability (hydraulic conductivity), L/T
P
Ah = hydraulic head loss, L
1 = length of fabric through which liquid is flowing, L
w = width of fabric, L
t = thickness of fabric, L
2 -1
0 = k t = transmissivity, L T
i = Ah/1 = hydraulic gradient, LL
2
A = wt = total cross sectional area available to flow, L
Numerous devices have been developed for measuring fabric and drainage product
transmissivity. Two such devices are shown in Figure 2-13. Both devices are
capable of measuring transmissivity while a normal pressure is being applied.
This is an essential feature of such devices, as the magnitude and nature of
the pressure applied to the surface of the material during the tests has a
great bearing on the measured value of transmissivity. The measurement of
transmissivity has not been standardized in any way. However, certain testing
conditions are essential for acquiring meaningful values. The hydraulic head
or heads used in the test should approximate the anticipated maximum heads
expected in the particular field applications, and the test must be performed
with an applied normal pressure that duplicates the pressure that will occur
in the field application. This will usually be soil pressure, but it could be
liquid or gas pressure or a combination thereof. If the pressure is to be
relatively great, it may be important to evaluate the effects of pressure over
a long period to ascertain whether creep of the material reduces the
2-21
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FIGURE 2-13
TEST DEVICES FOR MEASURING THE TRANSMISSIVITY OF FABRICS
AND MESHES UNDER LOAD
M
A = GEOTEXTILE
B = CONSTANT HEAD WATER SUPPLY
C= BASE PLATE
D = UPPER LOAD PLATE AND WATER
INLET CHAMBER
E = THERMOMETER
K = VERTICAL DEFORMATION MICROMETERS
M = MANOMETER MEASURING INLET HEAD
R= LOADING RAM
a. THE RAUMANN RADIAL FLOW DEVICE (AFTER RAUMANN, 1982)
SLIDING DOOR
CONSTANT
HEAD
EFFLUENT
PORT
NORMAL LOAD
To 10,000
BS) ' EFFLUENT BAFFLE
NET
OUTFLOW CHAMBER
EFFLUENT PORT
b. TRANSMISSIVITY DEVICE FOR MESHES AND NETS (AFTER WILLIAMS
et al 1984)
2-22
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transmissivity over time. Table 2-2 illustrates the range of transmissivities
that can be expected from fabrics and related products under a range of normal
loads.
2.3.5 Bubbling Pressure
Most engineering fabrics when clean and dry are somewhat hydrophobic, and
a small but measurable pressure is required to initiate flow through them.
This pressure is referred to as the "critical pressure head" (Mallard and
Bell, 1981) or "threshold gradient" (Bell and Hicks, 1983). This pressure
depends on the largest pore sizes of the fabric and the wettability of the
fibers. The heat-and resin-bonded nonwoven fabrics have the smallest pore
sizes and thus would have the highest bubbling pressure. Mallard and Bell
(1981) have developed a simple test to measure the head required to initiate
flow in a fabric. This quality is only likely to be of significance where
flow must take place across a fabric under very low hydraulic heads on the
order of 60 mm (2.4 in.) or less.
2.4 Environmental Endurance Properties
2.4.1 Ultraviolet Light Resistance
All the polymers used in the manufacture of engineering fabrics are
subject to degradation from exposure to the ultraviolet (UV) portion of sun-
light. This chemical degradation can be referred to as "actinism" or "photo-
chemical reaction," but in practice, it is almost universally referred to as
"UV degradation." Unprotected polypropylene is the polymer most rapidly
degraded by UV radiation, and polyesters are the least rapidly degraded. The
various polymers can be made much more resistant to UV attack by incorporating
certain chemical additives or an inert pigmenting material, most commonly car-
bon black, into the polymer formulation. The yarns or fabric may also be
coated after manufacture to prevent penetration of the harmful radiation. In
most applications, the fabric will be covered by soil, thereby protecting it
from extended exposure to sunlight. In these applications, protection is only
necessary before final covering. It is recommended that polyester fabrics and
fabrics stabilized against UV attack be covered within 30 days, and other
fabrics should be covered within 5 days.
Installations such as silt fences and other erosion control applications
that expose fabric to sunlight over extended periods require special con-
sideration be given to UV resistance. In these applications the maximum
amount of UV protection should be incorporated into the polymer.
The rate of attack by UV light depends on the geographic location of the
installation and may be increased by air pollution, repeated wetting and dry-
ing, and repeated freezing and thawing. The rate of attack also depends on
the construction of the product. Those fabrics having the greatest surface
area per unit volume of material will be degraded most rapidly. Thus the
slit-film woven fabrics will degrade the most rapidly, and the monofilament
woven and the grid structures will degrade the most slowly. Nonwoven fabrics
and multifilament woven fabrics will have an intermediate rate of degradation.
2-23
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Table 2-2
TRANSMISSIVITIES OF FABRICS AND GRIDS UNDER VARIOUS TEST CONDITIONS
Reference
Values calcu-
lated for a
sand drainage
layer
Minimum RCRAa
requirement
Williams et al.
(1984)
Normal
Load, kPa
Material and Test Conditions (psi)
457-mm (18-in.) sand layer having
_2
k = 10 cm/sec
305-mm (12-in.) sand layer having
k = 10 cm/sec
305-mm (12-in.) sand layer having
k = 10 cm/sec
3.2-mm- (1/8-in.-) thick grid; 10 mil 50 (345)
polyvinyl chloride and clay on
each side
0
m2/sec
(yd2/sec)
4.6 x
(5.5 x
3.1 x
(3.7 x
0.3 x
(0.36 x
1 x
(1.2 x
10l5
10 )
r
-— j
_ S
10 i)
io"5
10 5)
io~3
10~3)
Koerner and
Sankey (1982)
3.2-mm- (1/8-in.-) thick grid; heat- 50 (345)
bonded fabric and clay on each
side
3.2-mm- (1/8-in.-) thick grid; heat- 50 (345)
bonded fabric and clay one side,
rigid plate on other side
3.2-mm- (1/8-in.-) thick grid; 50 (345)
needled fabric and clay on each
side
3.2-mm- (1/8-in.-) thick grid; heat- 500
bonded fabric and clay on each (3,450)
side
1 layer needle-punched fabric; 10 (69)
30 percent silt, 70 percent clay
mixture on each side
1 layer needle-punched fabric; 10 (69)
70 percent silt, 30 percent clay
mixture on each side
0.8 x 10
(0.95 x 10 )
3 x IQ~3
(3.6 x 10 )
1 x 10
(1.2 x 10
1 x 10
(1.2 x 10" )
0.1 x 10 5
(0.12 x 10"°)
0.3 x io
(0.36 x 10
(continued)
Resource Conservation and Recovery Act.
2-24
-------
TABLE 2-2 (continued)
Reference
Koerner and
Sankey (1982)
Material and Test Conditions
1 layer needle-punched fabric;
85 percent silt, 15 percent clay
mixture on each side
Normal 0
Load, kPa m2/sec
(psi) (yd2/sec)
10 (69) 1.3 x 10";!
(1.55 x 10 )
Koerner and
Bove (1983)
Koerner and
Sankey (1982)
1 layer needle-punched fabric;
100 percent silt on each side
1 layer needle-punched fabric;
rigid plates on each side
1 layer needle-punched fabric
against rigid plates; range for
7 products tested
1 layer needle-punched fabrics
against rigid plates; range for
7 products tested
1 layer needle-punched fabric,
3.6 mm (0.14 in.) nominal
thickness; rigid plates on each
side
1 layer needle-punched fabric,
4.8 mm (0.19 in.) nominal
thickness; rigid plates on each
side
2 layers needle-punched fabric,
9.6 mm (0.38 in.) nominal
thickness; rigid plates on each
side
10
10
4.8
24
100
(69)
(69)
(33)
(165)
(689)
1.
(1.
2.
(2.
1.
(1.
6.
(7.
0.
(0.
1.
(1.
3.
(4.
6
9
1
5
2
4
2
4
6
7
5
8
5
2
x
x
X
X
X
X
X
X
X
X
X
X
X
X
10
10
10~s
10"^
10~s
10 ~
10 "I
io-5
io"5
10~S
10~5
10"
1°1
io"6
100 (689)
100 (689)
6.1
(7.3
io~jj
10 )
7.1 x io_jj
(8.5 x 10 )
Raumann (1982)
1 layer needle-punched fabric,
against rubber plattens; range
for 8 products tested
10 (69)
100 (689)
(3.6 x 10 °)
12 x 10~°
(14.4 x 10 ;?)
0.5 x 10^:
(0.6 x 10 J?)
4.1 x io"°
(4.9 x io~b)
2-25
-------
Outdoor weathering tests (for example, see ASTM D 1435 and E 838) and
laboratory-type accelerated weathering tests can be used to evaluate the
relative resistance of various products to UV degradation. The Xenon-Arc
lamp, when used with special filters as described in ASTM D 4355, correlates
well with the spectral distribution of sunlight and is the preferred apparatus
for laboratory evaluation of UV resistance. However, because of the factors
described above, no generally applicable relationship between outdoor weather-
ing and accelerated weathering tests can be given (Hoerchst Fibers Industries,
1979). The manufacturers of Xenon-Arc weatherometers claim that a 24-hr test
cycle in the Xenon-Arc apparatus corresponds to about 10 days of outdoor
weathering at average exposure values near Frankfort, Germany, or about 7 days
near Miami, Florida. However, many factors can combine to complicate the
relationship between weatherometer test results and normal outdoor exposure.
These factors include the spectral shifts that occur outdoors when cycling
between day and night, the interaction between light exposure and humidity
changes, frequency and duration of rainfall, air pollution, and temperature
changes that result in freeze-thaw cycles.
2.4.2 Chemical Resistance
2.4.2.1 Resistance To Soil Chemicals
No cases of fabric failure because of attack from chemicals present in a
natural soil environment were found in the literature. However, in cases of
fabric burial in soils having a very low or very high pH, consideration should
be given to the composition of the geotextile selected, as discussed in the
following section.
2.4.2.2 Resistance of Common Geotextile Polymers to Chemicals in
the Waste Disposal Environment
Fabrics will come into contact with chemical leachate when used in'
leachate collection systems and in cover designs where they would be below the
cover and act as reinforcement or as part of a gas venting system. Several
fabric manufacturers were contacted and asked to supply information on the
chemical compatibility of their fabrics with various chemicals known to be
common in hazardous waste landfills. Several stated that if the chemical
environment were known, they would perform tests to determine chemical com-
patibility of their fabric with specific wastes.
Tables 2-3 and 2-4 present tabulations of the chemical resistance of
polypropylene from two manufacturers of polypropylene resin that also manu-
facture finished geotextiles. Table 2-5 presents a tabulation of chemical
resistance of polyester fiber used in the manufacture of polyester geotex-
tiles. Results of chemical compatibility tests supplied by one manufacturer
for polypropylene, polyester, and nylon (nylon 6-6) are presented in Table 2-6
for exposure to certain acids, alkalis, inorganic salts, and organic
chemicals.
The data presented in the aforementioned tables are only useful for
screening purposes for a number of reasons. Differences in plastic formula-
tions and type and levels of additives can have a significant effect on a
2-26
-------
TABLE 2-3
CHEMICAL RESISTANCE OF POLYPROPYLENE^
Compounds are listed alphabetically.
Legend: 1. Satisfactory (no effect)
2. Generally satisfactory (minor effect)
3. Fair (noticeable effect)
4. Unsatisfactory (severe effect)
- No test data available
A reported value of "4" at room temperature (73°F) does not rule out completely the pos-
sibility of using the compound when only short contact time is involved.
COMPOUND
73°F 120°F 150°F 212°F
23°C 49°C 66°C 100°C
COMPOUND
73°F
23°C
1IO°F
49°C
150°F
66°C
212°F
100°C
Acetaldehyde
Acetate Solvents, Crude
Acetate Solvents, Pure
Acetic Acid, 10%
Acetic Acid, 50%
Acetic Acid, Glacial
Acetone (Dimethylketone)
Acetophenone
Acetylene
Air
1
1
1
1
1
1
1
3
2
3
1
1
_
—
4
Alcohol, Amy)
Alcohol, Butyl
Alcohol, Ethyl
Alcohol, Isopropyl
Alcohol, Methyl
Almond Oil
Aluminum Chloride
Aluminum Nitrate
Aluminum Sulphate
Alums
2
2
1
1
1
1
1
1
1
1
2
2
1
1
1
1
1
1
1
1
2
2
2
1
2
1
1
1
1
1
-
2
2
1
2
1
1
1
1
(continued)
Data from Amoco Chemicals Corporation (1980)
2-27
-------
TABLE 2-3 (continued)
COMPOUND
Ammonia, 25% sol.
Ammonia, concentrate
Ammonia, gas
Ammonium Acetate
Ammonium Carbonate
Ammonium Chloride
Ammonium Hydroxide
Ammonium Nitrate
Ammonium Sulphate
Amyl Acetate
Aniline
Antimony Trichloride
Apple Juice
Asphalt (tar)
Beer
Beet Juice
Benzaldehyde
Benzene/Benzol
Benzene Sulfonic Acid,
Benzoic Acid
Benzyl Alcohol
Bluing
Boric Acid
Brandy
Brine, Acid
73"F
23°C
1
1
1
1
1
1
1
1
1
4
2
1
1
1
1
1
1
2
10% 1
1
1
1
1
1
1
Bromine Water, Saturated 3
Butane
Butanol
Butyric Acid
Butyl Acetate
Butyl Phthalate
Calcium Bisulfite
Calcium Chloride, 50%
Calcium Hypochlonte
Calcium Hydroxide
Calcium Nitrate
Camphor Oil
Cane Sugar Liquor
Carbon Dioxide, dry
Carbon Dioxide, wet
Carbon Disulfide
Carbon Tetrachloride
Castor Oil
Caustic Soda, cone.
Caustic Soda, dil.
2
1
1
3
1
1
sol. 1
1
1
1
4
1
1
1
3
2
1
1
1
120°F
49°C
1
1
1
—
1
1
1
1
1
4
2
1
1
1
1
1
—
4
1
-
4
-
1
1
4
1
1
1
1
1
1
4
-
1
1
4
4
1
1
1
150°F
66°C
1
2
1
- ,
1
1
1
1
1
4
3
2
1
1
1
1
—
4
1
-
_
1
1
-
1
4
-
1
1
4
1
1
1
2
1
1
4
-
1
1
4
4
-
1
1
21 2° F
100°C
_
—
—
—
1
2
1
1
1
4
3
2
1
3
1
2
—
4
1
—
—
—
1
-
-
4
-
1
1
4
1
1
2
3
1
1
4
-
—
—
4
4
—
1
1
COMPOUND
Chlorobenzene
Chlorine, wet
Chlorine, dry
Chloroform
Chlorosulfonic Acid
Cholocate Syrup
Chromic Acid, 50%
Citric Acid, 10%
Clove Oil
Coconut Oil
Cod Liver Oil
Coke Oven Gas
Copper Salts
Copper Sulphate
Core Oils
Corn Oil
Cottonseed Oil
Creosote
Creosol
Cyclohexane
Cyclohexanol
Cyclohexanone
Decalin
Detergent Solution
Heavy Duty
Diacetone Alcohol
Dibutyl Phthalate
Diethyl Ether
Dimethyl Formamide
Dimethylamine
Dioctyl Phthalate
Dioxane
Epichlorohydrin
Ethers
Ethyl Acetate
Ethyl Chloride
Ethylene Chloride
Ethylene Glycol
Ferric Chloride
Ferric Sulfate
Ferrous Chloride
Ferrous Sulfate
73°F
23°C
2
3
4
3
4
1
1
1
2
1
1
1
1
1
1
1
1
1
1
3
1
2
4
1
1
1
2
1
1
3
2
1
3
2
4
2
1
1
1
1
1
Formaldehyde, 35% sol.1
Formalin, 40% sol.
1
Formic Acid,Anhydrous 1
Freon (12,22)
2
120°F
49°C
4
4
_
4
4
2
1
3
-
_
—
1
1
-
1
1
_
_
4
2
3
4
1
1
2
3
1
1
4
3
1
3
2
4
4
2
1
1
1
1
1
_
1
—
150"F
66°C
4
4
—
4
4
2
3
4
-
_
_
2
_
-
2
2
_
—
4
3
4
4
1
—
3
4
—
—
4
4
—
4
3
4
4
3
1
1
1
1
2
_
2
_
212"h
100°F
4
4
—
4
4
_
3
4
4
-
_
_
_
_
-
_
_
_
—
4
4
4
2
_
-
4
_
—
4
4
—
4
4
4
4
4
1
1
2
1
2
_
_
_
(continued)
2-28
-------
TABLE 2-3 (continued)
COMPOUND
Freon TF
Fuel Oil, No, 2 Distillate
Furfural
Gasoline
Gelatin
Glucose
Glue
Glycerine
Heptane
Hexane
Household Detergent
Hydraulic Oil
Hydrobromic Acid, 50%
73°F
23°C
1
2
4
4
1
1
1
1
2
2
1
2
1
Hydrochloric Acid, 38% cone 2
Hydrocyanic Acid
Hydrofluoric Acid 40%
Hydrofluoric Acid, 50%
Hydrogen Fluoride
Hydrogen
Hydrogen Peroxide
Hydrogen Peroxide, 3% sol.
Hydrogen Peroxide, 28% sol
Hydrogen Peroxide, dry
Hydrogen Sulfide, wet
Iodine Solution, H20
Iodine in Alcohol
Isooctane
Kerosene
Lacquer
Lacquer plus solvent
Lactic Acid, 80%
Lead Acetate
Lemon Oil
Ligrome
Lime Sulfur
Linseed Oil
1
1
1
1
1
1
1
. 1
1
1
1
1
2
2
1
1
1
1
3
1
1
1
Liquified Petroleum Gas(LPG) 2
Lubricating Oil
Lye
Magnesium Chloride
Magnesium Hydroxide
Magnesium Nitrate
Magnesium Sulfate
Malic Acid
Manganese Salts
2
1
1
1
1
1
2
1
120°F
49°C
2
3
4
4
1
1
—
1
4
4
1
3
1
2
—
1
—
—
-
1
_
2
1
1
—
_
3
3
—
—
1
1
4
1
-
1
3
3
—
1
1
1
1
3
1
150°F
66°C
3
4
4
4
1
1
—
1
4
4
2
4
3
3
—
2
-
-
-
1
_
3
2
2
—
—
4
4
—
—
1
1
4
—
-
2
4
4
—
1
1
1
1
3
1
212°F
100°C
4
4
4
1
1
-
—
4
—
COMPOUND
Maple Syrup
Mayonnaise
Meat Sauce
Mennen's "Skin Bracer
Mercurochrome
Mercuric Chloride
Mercury
Methanol, 100%
73° F
23°C
1
1
1
"1
1
1
1
1
Methyl Isobutyl Ketone 2
Methylene Chloride
3
— Methyl Isobutyl Carbinol 1
—
—
—
—
3
-
-
-
—
_
4
-
-
—
_
4
4
—
-
_
1
4
-
-
_
-
-
—
2
1
1
1
—
1
Milk
Mineral Oil (White)
Molasses
Motor Oil
Mustard Paste
Natural Gas
Neat's - Foot Oil
Nickel Chloride
Nickel Sulfate
Nitric Acid, dil.
Nitric Acid, 30%
Nitric Acid, 50%
Nitric Acid, Fuming
Nitrobenzene
Nitrogen Oxide
Nitrous Acids
Nutmeg Oil
Oleic Acid
Olive Oil
Orange Juice
Oxalic Acid, 50%
Oxygen Gas
Palmitic Acid
Peanut Oil
Peppermint Oil
Percholoroethylene
Perchloric Acid
Phenol
Phenol, 5% sol.
Phosphoric Acid, 85%
Phosphoric Acid, 50%
Phosphoric Acid, 25%
Photographic Sol.
Picric Acid
1
1
1
2
1
1
1
1
1
1
1
1
3
2
1
3
4
1
1
1
1
1
1
1
1
2
1
1
1
1
1
1
1
1
120°F
49°C
_
-
1
1
-
1
1
1
4
4
1
1
2
-
3
_
-
1
1
1
1
1
4
4
3
—
—
4
2
1
—
1
1
1
2
4
3
-
1
1
1
1
1
1
-
150°F
66°C
_
-
1
1
—
1
1
2
4
4
_
-
4
—
4
_
-
1
1
1
1
-
4
4
3
_
-
4
2
2
1
1
1
3
4
4
—
1
1
2
1
1
1
-
212°F
100°C
_
-
-
-
—
2
-
2
4
4
_
—
4
—
4
—
-
-
2
1
1
—
4
4
-
_
—
4
3
3
—
1
1
4
4
4
_
1
1
2
2
1
_
-
(continued)
2-29
-------
COMPOUND 73°F
23°C
Plating Sol. (any)
1
120°F
49°C
1
TABLE
150°F
66°C
1
2-3 (continued)
21 2° F
100°C
1
Potassium Bichromate/Sulfuric
Acid/Water (5/100/5)
Potassium Carbonate
Potassium Chlorate
Potassium Chloride
Potassium Hydroxide, 50%
Potassium Iodide
Potassium Permanganate,20%
Potassium Sulfate
Pyridme
Rice Bran Oil
Rosin, light
Saffiower Oil
Sauerkraut
Shellac
Shoe Polish, Liquid
Silicone Oil
Silver Nitrate
Soap Solution, 5%
Soapless Detergent
Sodium Bicarbonate
Sodium Bisulfate
Sodium Bisulfite
Sodium Borate
Sodium Bromide
Sodium Carbonate, 3% aq.
Sodium Carbonate, sat. sol.
Sodium Chlorate
Sodium Chloride, 10% aq.
Sodium Chloride, sat. sol.
Sodium Cyanide
Sodium Hydroxide, cone.
Sodium Hydroxide, 50%
Sodium Hypochlorite, cone.
Sodium Hypochlorite, 5%
Sodium Metaphosphate
Sodium Nitrate
Sodium Palmitate, sol.5%
Sodium Perborate
Sodium Phosphate, Alkaline
Sodium Phosphate, Acid
Sodium Phosphate, Neutral
Sodium Silicate
Sodium Sulfate
Sodium Sulfide
Sodium Sulfite
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
2
1
1
1
1
—
2
1
1
1
-
1
—
—
-
_
1
1
—
1
1
1
-
1
1
1
1
1
1
1
1
1
2
2
_
1
—
—
1
1
1
1
1
1
1
3
1
1
1
1
—
2
1
1
1
-
2
—
—
-
—
1
1
-
1
1
1
—
1
1
1
1
1
1
1
1
1
3
3
_
1
-
—
1
1
1
1
1
1
1
4
1
2
2
-
—
-
1
1
—
—
-
—
—
—
—
1
-
—
1
1
1
—
1
COMPOUND
Sodium Thiosulfate.hypo
Soybean Oil
Spindle Oil
Stearic Acid
Succinic Acid
Sulfate Liquor
Sulfur
Sulfur Chloride
Sulfur Dioxide, dry
Sulfur Dioxide, wet
Su If uric Acid, 100%
Sulfuric Acid, 98%
Sulfuric Acid, 50%
Sulfuric Acid, 10%
Sulfurous Acid
Tannic Acid
Tartaric Acid
Tea
Tetrahydrofuran
Tetralin
Toluene
Tomato Juice & Soup
Transformer Oil
73°F
23°C
. 1
1
1
1
1
1
3
3
1
1
2
2
1
2
4
2
1
1
Trichloroacetic Acid, 2N 1
Trichloroethylene
Trisdium Phosphate
Turpentine
2
1
2
120°F
49°C
1
1
1
-
1
—
4
4
-
-
4
3
3
4
4
1
2
1
3
1
3
150°F
66°C
1
1
4
-
1
-
4
4
-
-
4
4
2
1
1
1
1
1
3
4
4
1
4
1
4
1
4
212°F
100°C
—
-
4
-
-
-
4
4
-
-
4
4
3
2
-
1
-
1
-
3
4
1
4
-
4
-
4
Two-Stroke Oil (outboard
4
4
_
1
-
—
1
1
1
1
—
-
-
motor oil)
Urea
Vanilla
Varnish
Vaseline
Vaseline Oil
Vinegar
Vinegar, White
Water, Distilled & Tap
Water, Brine
Water, Sea
Wax Crayon
Wheat Germ Oil
Whisky
White Spirits
Wines
Xylene
Zinc Chloride
Zinc Sulfate
1
1
1
1
1
1
1
1
1
1
1
1
1
1
4
1
2
1
1
1
1
1
-
1
1
1
1
1
-
-
-
1
1
4
1
4
1
1
4
1
-
-
2
2
1
1
1
-
-
-
1
1
4
1
4
1
1
4
1
-
-
3
3
—
—
1
-
—
—
—
-
4
-
4
1
1
2-30
-------
TABLE 2-4
STRENGTH RETENTION OF POLYPROPYLENE YARNS AFTER
EXPOSURE TO CERTAIN CHEMICALS3'b
Chemicals
ACIDS
10 percent Acetic Acid
40 percent Acetic Acid
Glacial Acetic Acid
5 percent Benzoic Acid (in Isoproporal)
5 percent Hydrochloric Acid
13.3 percent Hydrochloric Acid
Cone. Hydrochloric Acid (Tech. grade)
10 percent Nitric Acid
40 percent Nitric Acid
Cone. Nitric Acid
10 percent Oxalic Acid
40 percent Peracetic Acid
60 percent Acid
Cone. Phosphoric Acid
5 percent Salicylic Acid (in Methanol)
10 percent Sulfuric Acid
40 percent Sulfuric Acid
Cone. Sulfuric Acid
10 percent Trichloroacetic Acid
BASES
25 percent Sodium Hydroxide
50 percent Sodium Hydroxide
Oxidizing Agents
After
24 Hours
99
100
104
101
103
97
101
103
101
102
105
100
103
100
98
102
104
87
100
100
101
100
After
1 Week
99
98
102
100
97
100
97
101
101
95
104
98
100
99
99
99
97
56
99
100
99
99
After
4 Weeks
99
99
99
102
97
99
102
102
97
93
101
88
102
100
101
102
101
40
103
100
100
100
(continued)
^Data from Phillips Fiber Corporation (n. d.).
Tests performed on industrial denier yarns using
ASTM D 2256
; pulled
at
8.5 mm/sec; strength reported as percentage of strength of unexposed yarns.
2-31
-------
TABLE 2-4 (continued)
Chemicals
31.4 percent Hydrogen Peroxide
50 percent Sodium Hypochlorite
SALTS
5 percent Ferric Chloride
5 percent Sodium Chlorite (Textone)
OTHER CHEMICALS
Acetone
Acetonitrile
Acetophenone
Acrylonitrile
Analine
Benzene
Benzaldehyde
Benzyle Alcohol
5 percent Biphenyl (in Methanol)
Butyl Acetate
Butyl Stearate
Carbon Disulfide
Carbon Tetrachloride
Chlorobenzene
Chloroform
Cotton Seed Oil
M-Cresol
Cyclohexane
Cyclohexanone
Decalin
Dibutyl Phthalate
1,4- Dioxane
Ether
After
24 Hours
100
98
99
99
98
101
102
102
102
97
98
99
101
98
96
98
99
97
98
98
102
99
97
100
97
100
98
After After
1 Week 4 Weeks
99
98
100
99
100
101
98
101
98
97
101
99
99
101
98
97
98
99
97
100
101
98
101
98
96
101
98
100
98
99
98
100
100
100
100
101
98
99
101
99
99
101
99
100
99
99
100
99
100
97
101
98
100
98
(continued)
2-32
-------
TABLE 2-4 (continued)
Chemicals
Ethyl Acetate
Ethylbenzene
Ethylene Glycol
Formaldehyde
5 percent Iodine (in CCL)
Linseed Oil
Methyl Salicylate
N, N - Dimethylocetamide
Nitrobenzene
5 percent Ortho-Phenyl Phenon (in Methanol)
5 percent Para-Dichlorobenzene (in Ether)
Petroleum Ether
60/40 Phenol/Tetrachloroethylene
Phenyl Hydrozene
Polypropylene Glycol
Pyridine
5 percent Sodium Dithionite
Tetrachloroethylene
Tetralin
Toluene
1, 2, 4, - Trichlorobenzene
Trichloroethylene
5 percent 1, 2, 4, - Trichloro-5-Nitrobenzene
(in Ether)
5 percent 2, 4, 6, - Trichlorophenol
(in Methanol)
1, 2, 4, - Trichlorotoluene
Toluene
Xylene
After
24 Hours
100
96
98
101
101
97
102
102
100
98
101
101
101
97
98
101
98
97
100
96
103
102
97
98
103
96
99
After
1 Week
97
101
101
100
98
99
101
99
98
99
98
98
99
100
99
101
99
98
99
99
102
97
99
99
100
99
99
After
4 Weeks
97
100
100
102
102
98
99
101
99
97
100
99
100
101
98
100
98
96
98
99
102
100
99
98
101
99
98
2-33
-------
TABLE 2-5
CHEMICAL RESISTANCE OF POLYESTER (from Hoerchst Fibers Industries 1979)
K5
I
OJ
Resistance to saturated aqueous solutions Of Inorganic chemicals after
various exposure times
Chemicals
aqueous solutions
Aluminium suphate
Ammonium chloride
Ammonium nitrate*
Ammonium sulphate
Ammonium sulphide 40 %
Calcium chloride*
Calcium nitrate*
Copper sulphate
Ferric chloride
Ferrous sulphate
Lead acetate
Magnesium chloride*
Magnesium sulphate
Nickel sulphate*
Potassium bichromate
Potassium bromide
Potassium carbonate
Potassium chlorate
Potassium chloride*
Potassium chromate*
Potassium nitrate
Potassium perchlorate
Potassium permanganate
Potassium sulphate
Silver nitrate 25 %
Sodium ammonium
hydrogen phosphate
Sodium bicarbonate
Sodium bisulphite
Sodium carbonate
Sodium chlorate
Sodium cloride
Sodium nitrate
Sodium perchlorate*
Sodium sulphate
Sodium tetraborate
Sodium thiosulphate*
Zinc chloride*
Zinc sulphate*
d. = destroyed *
P.H
1
2.9
5.1
4.8
4.6
9.6
7.2
3.9
3.5
0.8
3.0
5.7
4.0
6.6
4.5
3.7
6.5
13.1
6.9
8.0
9.4
8.8
9.9
9.7
7.5
4.6
8.2
7.8
4.1
11.2
7.4
7.4
8.3
5.8
5.4
9.3
7.4
2.4
4.0
50%
Exposure time in month
3 6 12 1 3 6 12
Tenacity Knot tenacity
ratio (%)
100 100 100
100 100 100
100 100 100
100 100 100
50 d. d.
100 100 100
100 100 100
100 100 100
100 100 100
100 100 100
100 100 100
100 100 100
100 100 100
100 100 100
100 100 100
100 100 100
100 100 100
100 100 100
100 100 100
100 100 100
100 100 100
100 100 100
100 100 100
100 100 100
100 100 100
100 100 100
100 100 100
100 100 94
100 100 100
100 100 100
100 100 100
100 100 100
100 100 100
100 100 100
100 100 100
100 100 100
100 100 100
100 100 100
Resistance to inorganic and
Chemicals
organic acids after various exposure times
PH
ratio (%)
100 100
100 100
100 100
100 100
d. 55
100 100
100 100
100 100
100 100
100 100
100 100
100 100
100 100
100 100
100 100
100 100
96 100
100 100
100 100
100 100
100 100
100 100
94 100
100 100
100 100
100 100
100 100
94 100
94 100
100 100
100 100
100 100
100 100
100 100
100 100
100 100
100 100
100 100
100 100
100 100
100 100
100 100
d. d.
100 100
100 100
100 100
100 100
100 100
100 100
100 100
100 100
100 100
100 100
100 100
93 91
100 100
100 100
100 100
100 100
100 100
99 98
100 100
100 100
100 100
100 100
100 100
100 100
100 100
100 100
100 100
100 100
100 100
100 100
100 100
100 100
100 100
100
100
100
100
d.
100
100
100
100
95
100
100
100
100
96
100
B4
100
95
93
100
100
88
100
100
86
100
100
93
100
100
100
100
100
95
95
100
100
Acetic acid 15 %
Acetic acid cone.
Acetic anhydride
Benzole acid*
Boric acid**
Chlorosulphonic acid
Chromic acid**
Citric acid 15 %
Citric acid 25 %
Formic acid cone. <
Hydrochloric acid 15 % <
Hydrochloric acid 20 % <
Hydrochloric acid 30 % <
Hydrochloric acid 37 % <
Hydrofluoric acid 10 %
Hydrofluoric acid 20 %
Hydrofluoric acid 38. ..40 %
Lactic acid cone
Malic acid 25 %
Nitric acid 15 % <
Nitric acid 20 % <
Nitric acid 30 % <
Nitric acid 50 % <
Nitric acid 65 % <
2.0
0.1
3.5
1.5
1.2
0.1
0.1
0.1
0.1
0.1
0.7
1.3
0.1
0.1
0.1
0.1
0.1
Exposure time in months
1 3 6 12 1 3 6 12
Tenacity Knot tenacity
ratio (%)
100 100
100 100
100 100
100 100
100 100
d.i. d.i.
98 96
100 100
100 100
100 100
100 100
93 83
78 52
43 20
97 96
95 94
94 86
100 100
100 100
100 100
90 85
87 66
57 27
7 d.
100 100
100 100
100 100
100 100
100 100
d.i. d.i.
85 83
100 100
100 100
100 100
100 100
72 35
32 16
d. d.
95 93
93 86
70 48
100 100
100 100
100 100
69 52
52 26
10 d.
d. d.
ratio (%)
100 100
100 100
100 100
100 100
100 100
d.i. d.i.
85 74
100 100
100 100
100 100
100 100
80 71
54 45
47 22
99 95
93 87
92 85
100 100
100 100
100 100
81 68
64 62
45 23
d. d.
100 100
100 100
100 97
100 100
100 100
d.i. -
73 72
100 100
100 100
100 100
100 100
63 41
23 d.
d. d.
88 70
86 70
66 47
100 100
100 94
100 100
66 45
43 23
d. -
d. d.
(continued)
™™,
NOTE: d. = destroyed.
* Saturated alcoholic solutions.
** Aqueous solution.
-------
TABLE 2-5 (continued)
Chemicals
pH Exposure time in months
1 3 6 12 1 3 6 12
Tenacity Knot tenacity
ratio (%) ratio (%}
Chemicals
Oxalic acid"
Phosphoric acid 20 %
Phosphoric acid 50 %
Phosphoric acid 85 % <
Stearic acid »
Sulphuric acid 15 % <
Sulphuric acid 38 %
(battery acid) <
Sulphuric acid 50 %
Sulphuric acid 70 %
Sulphuric acid 90 %
Sulphuric acid cone. 98 % <
0.6
0
0
0
a
0
0
0
a
.1
.1
.1
.1
.1
.1
.1
.1
100
98
98
100
100
100
100
98
88
d.i.
d.i.
100
97
98
100
100
100
100
95
83
d.i.
d.i.
100
95
96
100
100
100
100
94
76
d.i.
d.i.
100
92
95
100
100
100
100
92
72
d.i.
d.i.
100
100
100
100
100
100
100
96
83
d.i.
d.i.
100
97
100
100
100
100
100
95
77
d.i.
d.i.
100
90
100
100
100
100
97
91
70
d.i.
d.i.
100
86
98
100
100
100
89
75
66
d.i.
d.i.
pH Exposure lime in iwonths
1 3 6 12 1 3 & 12
Tenacity Knot tenacity
ratio (%) ratio (%)
Caustic soda solution
2%
Caustic soda solution
5%
Caustic soda solution
10%
Caustic soda solution
15%
Caustic soda solution
20%
Caustic soda solution
30 %
Diethylamine
Hydrazine 2 %
Hydrazine 5 %
Triethanolamine
Urea 50 %
12.8
12.5
12.4
12.1
11.8
11.2
13.5
10.6
10.8
13.3
10.4
90
48
47
d.
d.
d.
79
95
92
92
98
86
45
d.
d.
d.
d.
75
88
76
86
97
74
15
d.
d.
d.
d.
69
86
51
79
97
50
d.
d.
d.
d.
d.
55
76
15
66
91
86
55
38
d.
d.
d.
78
95
83
90
100
83
45
d.
d.
d.
d.
76
88
73
83
100
61
19
d.
d.
d.
d.
67
79
35
69
93
57
d.
d.
d.
d.
d.
49
75
-
68
92
I
OJ
Ul
(continued)
*
**
Saturated alcoholic solutions.
Aqueous solution.
-------
TABLE 2-5 (continued)
NJ
ON
Resistance to alkalis after various exposure times
Resistance to organic chemicals (solvents) after various exposure Mmes
Chemicals
Ammonia
Ammonia
Ammonia
Ammonia 2 %
Ammonia 5 %
Ammonia 10 %
Ammonia 15 %
Ammonia 20 %
Calcium hydroxide 15 %
Calcium hydroxide 30 %
Calcium hydroxide 50 %
Caustic potash solution
0,1 %
Caustic potash solution
2 %
Caustic potash solution
5 %
Caustic potash solution
10%
Caustic potash solution
20%
Caustic potash solution
30 %
Caustic potash solution
40%
Caustic soda solution
0.1%
pH
e
9
10
11.4
12.2
12.5
13.2
13.4
12.4
12.4
12.4
12.5
13.4
13.7
14.0
14.0
14.0
14.0
12.1
1
97
96
95
83
65
15
d.
d.
95
93
92
98
68
81
71
7
d.
d.
100
Exposure time in months
3 6 12 1 3 6
Tenacity Knot tenacity
ratio (%) ratio (%)
96
95
92
68
d.
d.
d.
d.
80
79
64
97
87
71
32
d.
d.
d.
100
89
88
87
41
d.
d.
d.
d.
73
71
29
95
80
51
d.
d.
d.
d.
100
86
85
84
d.
d.
d.
d.
d.
33
32
d.
90
62
18
d.
d.
d.
d.
94
100
100
95
83
64
11
d.
d.
88
71
70
95
92
83
50
11
d.
d.
-
100
97
92
64
d.
d.
d.
d.
87
84
80
90
85
„
78
38
d.
d.
d.
-
100
85
84
25
d.
d.
d.
d.
70
69
62
88
74
49
d.
d.
d.
d.
-
12
93
83
82
d.
d.
d.
d.
d.
-
-
d.
86
68
23
d.
d.
d.
d.
-
Chemicals
Acetone
Amyl acetate
Aniline
Benzaldehyde
Benzcatechin**
Benzene
Benzole acid amide*
Benzyl alcohol
Butanol
Butyl acetate
Carbon tetrachloride
Chloramine
Chloroform
m-cresol
Cyclohexanone
Cyclohexylamine
Crude oil
Diacetone alcohol
Dimethyl formamide
Dimethyl sulphoxide
Epichlorhydrin
Ethanal
Ether
Ethyl acetate
Exposure time in months
1 3 6 12 1 3 6 12
Tenacity Knot tenacity
ratio (%) ratio (%)
100 100 100 100 100 100 100 100
100 100 100 100 100 100 100 100
100 100 100 100 100 100 100 100
100 100 100 100 100 100 100 100
100 100 100 100 100 100 99 98
100 100 100 100 100 100 100 100
100 100 100 100 100 100 100 100
100 92 78 53 100 100 90 80
100 100 100 100 100 100 100 100
100 100 100 100 100 100 100 100
100 100 100 100 100 100 100 98
100 100 100 98 100 100 100 90
100 100 100 100 100 100 100 100
100 100 100 100 100 100 100 100
100 100 100 100 100 100 100 100
86 83 68 57 90 77 70 65
100 100 100 100 100 100 98 90
100 100 100 100 100 100 100 100
100 100 100 100 100 100 100 96
100 100 100 100 100 100 100 100
100 100 100 100 100 100 100 100
100 100 100 100 100 100 100 100
100 100 100 100 100 100 100 100
100 100 100 100 100 100 100 100
(continued)
*
**
Saturated alcoholic solution.
Saturated aqueous solution.
-------
NJ
I
CO
—I
TABLE 2-5 (continued)
Resistance to organic chemicals (solvents) after various exposure Nme» Resistance to fuels after various exposure times
Chemicals
Formaldehyde 30 %
Formamide
Fuel oil EL
Glycol
n-Hexylamine
Hydroquinone*
Isopropyl alcohol
Methyl acetate
Methyl alcohol
Methylene chloride
Methyl ethyl ketone
Mineral oil
Nitrobenzene
Petroleum
Phenol*"
m-Phenylene diamine"
2-Phenylethylalcohol
Phloroglucinol*
Pyridine
Pyrogallol
Resorcinol**
White spirit
Styrene
Tetrachloroethane
Toluene
Trichloroethylene
Trimethylamine
Turpentine
Xylene
Exposure time in months Chemicals
1 3 6 12 1 3 6 12
Tenacity Knot tenacity
100 100 100 100 100 100 100 100 Petrol, normal-grade
100 100 100 100 100 100 100 100 Petrol, super-grade
100 100 100 100 100 89 86 82 Diesel
100 100 100 100 100 100 100 100 Benzene
21 d. d. - 49 d. d. - Jet propellant JP 1
100 100 100 100 100 100 100 100 Jet propellant JP 4
100 100 100 100 100 100 100 100 Isooctane
100 100 100 100 100 100 100 100
100 100 100 100 100 100 100 100
100 100 100 100 100 100 100 100
100 100 100 100 100 100 100 100
100 100 100 100 100 100 100 100
100 100 100 100 100 100 100 100
100 100 100 100 100 100 100 100
100 100 100 100 100 100 100 100
100 100 100 100 100 100 100 100
100 100 100 100 100 100 100 100
100 100 100 100 100 100 100 100
100 100 100 100 100 100 100 100
100 100 100 100 100 100 100 100
100 100 100 100 100 100 100 100
100 100 100 100 100 100 100 100
100 100 100 100 100 100 100 100
100 95 93 92 100 89 85 81
100 100 100 100 100 100 100 100
100 100 100 100 100 100 100 100
80 24 d. d. 82 56 d. d.
100 100 100 100 100 100 100 97
100 100 100 100 100 100 100 98
Exposure
1 3
Tenacity
100 100
100 100
100 100
100 100
100 100
100 100
100 100
100 100
time in weeks
7
ratio (%)
100
100
100
100
100
100
100
100
14
100
100
100
100
100
100
100
100
28
100
100
100
100
100
100
100
100
(continued)
*
**
***
Saturated alcoholic solution.
Saturated aqueous solution.
50 percent alcoholic solution.
-------
TABLE 2-5 (concluded)
Resistance to fertilizers after various exposure times
Chemicals
I
U)
00
pH Exposure time in months
1 3 6 12 1 3 6 12
Tenacity Knot tenacity
ratio (%) ratio (%)
Ammonium sulphate*, dry
Ammonium sulphate", moist
*Blaukorn*
Blaukorn, moist 50 % 4.6
Calcium nitrate
Calcium nitrate, moist
50%
Calcium cyanamide, not
oiled, dry
Calcium cyanamide, not
oiled, wet 10 % 11.5
•Grunkorn*
Griinkorn, moist 50 % 6.7
Lime, slaked
Lime, slaked, moist 50 % 12.3
NPK 12/12/18, dry*
NPK 12/12/18 moist 50 % 4.9
NPK 15/15/15, dry*
NPK 15/15/15 moist 50 % 4.0
•Rotkorn*
Rotkorn, moist 50 % 3.8
Thomas meal*
Thomas meal, moist 50 % 12.3
Urea
Urea, moist 50 % 10.4
Urea, 35 %
Ammonium nitrate 35 % 7.3
Water, 30 %
100 97 96 84 100 98 91 90
4.2 92 92 91 83 96 94 87 85
93 92 91 90 100 97 89 88
92 90 88 87 82 87 85 84
96 95 95 92 97 96 88 83
5.7 92 91 91 88 96 90 86 82
95 93 91 90 93 92 89 86
85 73 66
94 95 88
86 86 85
90 89 89
88 78 64
95 94 92
94 93 89
97 96 95
96 93 92
98 96 93
97 96 92
90 89 88
80 74 61
99 98 97
98 97 97
13 88 74
86 96 93
83 86 86
86 91 86
d. 86 75
89 99 96
85 88 85
90 100 98
88 85 83
92 98 94
91 91 80
86 92 88
35 77 75
93 100 100
91 100 100
71 20
90 83
85 83
85 80
62 d.
95 92
83 82
96 94
80 79
93 90
78 76
84 83
64 60
94 93
93 92
95 94 93 - 94 87 83
* Fertilizer was used in normal commercial condition.
** Fertilizer was mixed with water to form a 50 percent mixture.
-------
TABLE 2-6
EFFECT OF CHEMICAL EXPOSURE ON BREAKING STRENGTH AND APPEARANCE OF SYNTHETIC FIBERS
Exposure Conditions
Concentration Temperature
Acids
Chromic acid
Hydrobromic acid
Hydrochloric acid
Hydrochloric acid
Hydrochloric acid
Hydrochloric acid
Hydrofluoric acid
Nitric acid
Nitric acid
Nitric acid
Nitric acid
Phosphoric acid
Phosphoric acid
Sulfamic acid
Sulfuric acid
Sulfuric acid
Sulfuric acid
Sulfuric acid
Sulfuric acid
Sulfuric acid
Sulfuric acid
Alkalis
Ammonium hydroxide
Ammonium hydroxide
Sodium hydroxide
Sodium hydroxide
Sodium hydroxide
Sodium hydroxide
Sodium orthosilicate
Saturated Salt
Solution
Aluminum chloride
Ammonium thiocyanate
Calcium chloride
Copper sulfate
Ferric chloride
Ferric chloride
Silver nitrate
Sodium nitrate
Zinc chloride
Organic Chemical
Acetic acid
Acetone
Benzaldehyde
Benzene
Butyrolactone
Chlorobenzene , mono-
percent
10.0
10.0
10.0
10.0
37.0
37.0
10.0
10.0
10.0
70.0
95.0
10.0
85.0
10.0
10.0
10.0
60.0
60.0
60.0
80.0
96.0
58.0
58.0
10.0
10.0
40.0
40.0
1.0
100
100
100
100
100
100
°C (°F)
21.1 (70)
21.1 (70)
21.1 (70)
71.1 (160)
21.1 (70)
71.1 (160)
21.1 (70)
21.1 (70)
98.9 (210)
21.1 (70)
21.1 (70)
98.9 (210)
21.1 (70)
21.1 (70)
21.1 (70)
98.9 (210)
21.1 (70)
21.1 (70)
98.9 (210)
21.1 (70)
21.1 (70)
21.1 (70)
21.1 (70)
21.1 (70)
98.9 (210)
21.1 (70)
98.9 (210)
98.9 (210)
21 (70)
93 (200)
93 (200)
21 (70)
21 (70)
93 (200)
93 (200)
93 (200)
93 (200)
21 (70)
21 (70)
21 (70)
21 (70)
93 (200)
21 (70)
Time
Hours
10
10
1,000
10
1,000
10
10
1,000
10
10
1,000
10
10
10
1,000
10
10
1,000
10
1,000
1,000
10
1,000
1,000
10
1,000
10
10
1,000
10
10
1,000
1,000
10
10
10
10
1,000
1,000
1,000
1,000
10
1,000
Strength Loss Caused by Chemical Exposure
Polypropylene
c
none
none
none
none
none
none
none
none
none
none
considerable0
none
none
none
none
none
none
none
none
none
none
none
none
none
none
none
none
none
none
none
none
none
none
none
c
none
none
none
none
none
none
none
none
none
Polyester
none
none
none
moderate
moderate
slight
none
none
slight
—
none
none
none
none
none
none
none
slight
moderate
—
none
degraded
considerable
degraded
degraded
degraded
none
none
none
none
none
none
none
none
none
none
none
none
none
none
none
none
Nylon 6-6
considerable**
slight
considerable
considerable
—
—
slight
considerable
degraded
—
—
slight
degraded
none
considerable
considerable
degraded
—
—
—
—
none
none
none
none
none
none
none
none
none
none
none
none
appreciable
none
none
degraded
slight
none
none
none
none
none
(continued)
Change in breaking strength of fibers (test procedure not reported).
none = 90 percent or more of original strength retained.
slight • 80 to 98 percent of original strength retained.
moderate = 60 to 79 percent of original strength retained.
considerable = 20 to 59 percent of original strength retained.
.degraded = 0 to 19 percent of original strength retained.
Data from the Du Pont Company.
Specimen was discolored by the exposure.
2-39
-------
TABLE 2-6 (continued)
Exposure Conditions
Organic Chemical
Chlorobenzene, mono-
m-Cresol
m-Cresol
m-Cresol
Cyclohexanone
p-Dichlorobenzene
Dimethyl acetamide
Dimethyl formamide
Dimethyl sulfoxide
Ethylene glycol
Formaldehyde
Formic acid
Methyl salicylate
Methylene chloride
Naphthalene
Nitrobenzene
Nitrobenzene
Oxalic acid
Perchlorethylene
Perchlorethylene
Phenol
Phenol
o-Pheny Ipheno 1
Propylene carbonate
Pyridinc
Stoddard solvent
Tetrachloroethane
Tetrachloroethane
Trifluoroacetic acid
Turpentine
m-Xylene
m-Xylene
Concentration
percent
100
100
100
100
100
100% (Powder)
100
100
100
100
10% in HO
92% in H^O
100
100
100% (Powder)
100
100
Sat. Sol. in
100
100
10% in HO
100 ^
10% in CH OH
100
100
100
100
100
100
100
100
100
Temperature
"C (°F)
93 (200)
21 (70)
93 (200)
202 (200)
93 (200)
21 (70)
93 (200)
153 (307)c
93 (200)
21 (70)
21 (70)
93 (200)
21 (70)
21 (70)
21 (70)
21 (70)
93 (200)
21 (70)
93 (200)
121 (250)c
21 (70)
21 (70)
21 (70)
93 (200)
21 (70)
93 (200)
21 (70)
93 (200)
21 (70)
21 (70)
93 (200)°
139 (282)c
Time
Hours
10
1,000
10
10
10
1,000
10
10
10
1,000
1,000
10
1,000
1,000
1,000
1,000
10
1,000
10
10
1,000
10
1,000
10
1,000
10
1,000
10
1,000
1,000
10
10
Strength Loss
Polypropylene
slight
none
none
degraded
degraded
none
none
degraded
none
none
none
none
none
none
none
none
none
none
appreciable
degraded
none
none
none
none
none
none
none
none
d
none
none
none
degraded
Caused by Chemical Exposure
Polyester
none
none
degraded
degraded
none
none
none
degraded
none
none
none
none
none
none
none
none
none
none
none
none
slight
degraded
none
none
none
none
none
moderate
degraded
none
none
none
Nylon 6-6
none
degraded
degraded
—
none
none
none
none
none
none
none
--
none
none .
d
none
d
none
none
none
none
none
degraded
degraded
none
none
none
none
none
none
degraded
none
none
slight
dBoiling point of chemical agent.
2-40
-------
given plastic's reaction to a given chemical. One cannot assume that a
plastic fiber or fabric will behave similarly with similar chemicals. Also,
the concentrations of chemicals likely to come into contact with fabrics in
hazardous waste management applications will in many cases be far less than
the concentrations used in the chemical compatibility tests commonly avail-
able. However, chemicals present in hazardous waste disposal sites may be
present in combinations that cause effects that would not be caused by a
single reagent. In addition, fabrics installed in waste containment facili-
ties are expected to function for at least 30 years without failure. Thus
the need for long-term chemical resistance testing for periods of a year or
more are clearly indicated. Finally, in many waste containment applications,
the fabric will be under long-term static stress because it has to bridge gaps
in drainage gravel when used in filtering and drainage applications and when
put into direct tension in reinforcement applications. Environmental stress
cracking may take place under these conditions and may lead to failure of the
fabric, whereas the fabric might show little deterioration in a similar
chemical environment that is not under stress.
Short-term screening tests of the type described in ASTM D 543 are seldom
predictive of service life. This type of test measures the change in a prop-
erty of an item after being immersed in a liquid reagent for 7 days. The
weight change, dimensional change, and tensile strength change are all used to
evaluate the effects of immersion. Swelling potential is an important con-
sideration in evaluating fabrics for potential use in a chemical environment
because excessive swelling may cause a reduction in the fabric porosity and
permeability, leading to a fabric's failure as a filter or drainage material.
To evaluate strength reduction under static load, it is necessary to perform
creep and creep rupture tests such as in ASTM D 2990, in which test specimens
are statically loaded while immersed in a liquid of composition comparable to
that likely to be found in a specific application. The following discussion
of specific plastics is based on the conventional screening tests such as
ASTM D 543.
Polypropylene shows good chemical resistance to aqueous solutions of most
acids, bases, and inorganic salts, even at high concentrations, it is subject
to attack by strong oxidizing agents. No known solvent exists for poly-
propylene at room temperature. However, polypropylene will absorb chemicals
to an extent that depends on temperature and the polarity of the organic mate-
rial. Absorption increases with increasing temperature and decreasing polar-
ity of the media. The effect of absorption is to cause swelling and a reduc-
tion of tensile strength. Chlorinated hydrocarbons cause swelling of
polypropylene at room temperature and some will dissolve polypropylene at
71.1° C (160° F).
Hoerchst Fibers, a major manufacturer of polyester fibers and geotextiles
in the United States, has published extensive information on the chemical
resistance of their fibers. Their work indicates that polyester is resistant
to aqueous solutions of organic salts except 40-percent solutions of ammonium
sulfide and potassium carbonate. Polyester shows good resistance to organic
and dilute inorganic acids, even at low pH values. However, degradation
occurs and becomes rapid as the acids become concentrated.
2-41
-------
Polyester shows very limited resistance to alkalis and is particularly
sensitive to ammonia and sodium hydroxide (caustic soda) solutions. At con-
centrations above 15 percent, polyester yarns are completely destroyed by
these chemicals.
Polyester is resistant to very many organic chemicals. Exceptions are
some amines such as chloramine, cyclohexylamine, hexylamine, and trimethyla-
mine. Polyester is slightly attacked by benzyl alcohol and tetrachlorethane
at room temperature, causing a reduction in strength with time. Polyester is
very resistant to fuels and bituminous materials.
Only limited information was obtained on the chemical resistance of
nylon, since this material is used only to a very limited extent in geotex-
tiles. Nylon is reported to have good resistance to aromatic and aliphatic
solvents, common automotive oils and fuels, and refrigerants. Nylon is
attacked by strong acids, bases, and phenol. Nylon is also attacked by
aqueous solutions of ferric chloride and zinc chloride.
Literature available from Du Pont, the sole manufacturer of Kevlar,
states that the fiber has excellent chemical resistance except for a few
strong acids (Du Pont Company, 1976). More detailed information on the prop-
erties of this material was not presented in the literature for this fiber.
2.4.2.3 Chemical Resistance Tests of Finished Fabrics
Calhoun (1972) reported the results of short- and long-term tests on fab-
rics being marketed in 1970. Five of the fabrics were polypropylene monofila-
ment woven fabrics, one was a polypropylene staple-needled fabric, and one was
a polyvinylidene chloride woven fabric. The fabrics were tested for resist-
ance to alkali, acid, JP-4 fuel, and toluene. For the short-term alkali
tests, equal amounts of sodium hydroxide and potassium hydroxide were dis-
solved in water to make a pH 13 solution, and fabric specimens were immersed
in this solution at 60°-65.5° C (140°-150°F) until the fabric reached a
constant weight. For the short-term acid tests, the fabrics were immersed in
a hydrochloric acid solution adjusted to a pH of 2 and maintained at a
temperature of 60°-65.5° C (140°-150° F) for 14 days. The effect of JP-4 fuel
was determined by immersing fabric samples at room temperature for 24 hours
and 7 days. The long-term immersion tests were carried out at room tempera-
ture with (a) an equal part solution of sodium hydroxide and potassium hydrox-
ide adjusted to pH 10, (b) a pH 3 hydrochloric acid solution, and (c) toluene.
The effects of these chemicals on the fabrics were measured by comparing
the tensile strength of the specimens after immersion with specimens that had
not been immersed. For the fabrics tested, none lost more than 10 percent
strength in the short-term exposure or 2 percent in long-term exposure to the
alkali solutions. None of the fabrics showed any significant decrease in
strength because of exposure to acid in either short- or long-term tests. In
the fuel immersion tests, the needled polypropylene lost approximately
30 percent of its original strength after 1 week of immersion in JP-4 fuel,
and it lost 57 percent of its machine direction strength in the long-term
immersion tests in toluene and 30 percent in the cross machine direction. One
of the polypropylene monofilament woven fabrics had 14 percent strength loss
2-42
-------
after JP-4 fuel immersion, but it showed no effect from toluene. The
polyvinylidene chloride fabric and one polypropylene woven fabric lost more
than 10 percent strength after 12 and 6 months immersion in toluene,
respectively. No significant deterioration occurred with the other cloths.
Table 2-7 provides a summary of the responses of geotextile plastics to a
variety of chemicals. The table is a summary of data extracted from previous
tables. The chemicals selected are, with a few exceptions, the same chemicals
used by Anderson and Brown (1981) in their evaluation of the susceptibility of
clay liners to chemical attack.
Currently the ASTM Committee on Geotextiles is working to develop a
standard method for "Resistance of Geotextiles to Chemical Environments." The
test method as currently proposed evaluates the geotextile in terms of weight
change and loss of tensile strength from exposure. The test method is similar
to D 543 and allows for a minimum immersion time of 1 month and testing at
TABLE 2-7
EFFECTS OF VARIOUS CHEMICALS ON GEOTEXTILE PLASTICS3
Chemical
Acetic acid
Sulphuric acid
Sodium hydroxide
Aniline
Acetone
Ethylene glycol
Isooctane
Xylene
Chlorobenzene
Methylene chloride
Concentration
Percent
100 (glacial)
10b (pH < 1)
10b (pH = 12.4)
100
100
100
100
100
100
100
Effect of Chemicals on
Polyester
None
None
Destroyed
None
None
None
None
Some
Some
None
Polypropylene
None
None
None
None
None
None
Some
Some
Some
Substantial
Nylon
Substantial
Substantial
None
—
None
None
—
None
None
None
(dichloromethane)
Ferrous sulfate
Saturated
None
None
Consensus of data available to the author for room-temperature exposure of
at least 1 month.
Aqueous solution.
2-43
-------
various temperatures. Efforts to validate the test by round-robin testing
have indicated very poor agreement between participating laboratories, and the
method is currently under revision.
2.4.3 Biological Resistance
No known cases exist of a geotextile failures resulting from attack by
soil microorganisms, even though some fabric installations are more than
20 years old. Certain forms of bacteria are known to cause the precipitation
of ferric hydroxide and sulfides; these precipitates, along with the oxidizing
bacterial colonies, cause slimes that have been observed on fabrics used in
drainage systems. These slimes can potentially clog fabric filters, though
there have been no reported instances of fabrics actually being attacked by
these or other organisms. No evidence exists at this time to suggest that
fabrics would be more likely to clog from these formations than would granular
materials used for the same purpose.
In an investigation of the failure of a concrete block erosion control
revetment on a freshwater lake, algae was observed to be growing on the sur-
face of a needle-punched nonwoven fabric that had been placed as a filter
beneath the blocks (Lee, 1977). In this installation, samples of the fabric
were removed from the site and tested for permeability. Laboratory tests
revealed that the combination of algal growth and entrapped soil particles had
reduced fabric permeability from 4 * 10 cm/sec (1100 ft/day) to
_3
5 x 10 cm/sec (14 ft/day). Though the algal growth was concluded not to
have contributed to the failure of the revetment, it is apparent that given a
constantly moist environment and sufficient sunlight, algae could contribute
to the clogging of a fabric used for erosion control. In the application just
described the algae was only found on those areas between the revetment blocks
exposed to direct sunlight. Thus protecting an erosion control fabric from
direct sunlight after installation serves the dual purpose of eliminating
growth of algae as well as reducing deterioration from ultraviolet light.
Although the synthetic fibers used in the manufacture of geotextiles
appear to be impervious to microorganisms, tests have been developed to
evaluate the effect of mildew and microorganisms on fabrics (e.g. ASTM Methods
G 21, G 22, G 29, and D 3083, and the American Association of Textile Chemists
and Colorists test for mildew and rot resistance of textiles). These tests
are listed in Appendix B.
In addition to microorganisms, fabrics are subject to damage by burrowing
animals and by the growth of plant roots through fabric pores. Though no
investigations of damage by root growth are known, it seems plausible that
plant roots could reduce the permeability of fabric filters, especially when
fabrics are used in landfill covers and cover soil depths are 0.45 to 0.6 m
(1-1/2 to 2 ft) or less.
2-44
-------
2.4.4 Miscellaneous Environment Effects.
2.4.4.1 Temperature Extremes
Calhoun (1972) performed tests on polypropylene and polyvinyldene
chloride fabrics to evaluate their embrittlement at low temperature. None of
the fabrics evidenced cracking at temperatures to minus -51° C (-60° F). In a
series of strength tests on the same fabrics performed at temperatures from
-17.7° to 82.2° C (0° to 180° F), strength differences did not appear to be
significant, and there was no consistent trend of strength change with test
temperature. The results did show that the strain at failure increased
somewhat as temperature was increased from -17.7° to 82.2° C (0° to 180° F).
Allen et al. (1982) reported that tensile tests of a representative
sampling of fabric types tested at room temperature (22° C, or 71.6° F) and in
a subfreezing environment (-12° C, or 10.4° F) showed elongations at failure
and decreased significantly for the polypropylene fabrics tested and for heat-
bonded fabrics. The modulus and strength of heat-bonded fabrics was shown to
increase with decreasing temperature.
2.4.4.2 Freeze-thaw Cycles
Calhoun (1972) subjected fabrics to 300 2-hr cycles of freezing and thaw-
ing in which the temperature was varied between -17.7° and 4.4° C (0° and
40° F) and found that there was no change in physical strength properties
after cycling. Allen et al. (1982) found no effect on strength after
subjecting a representative sampling of fabric types to 50 24-hr cycles of
freezing and thawing in fresh water.
2.4.4.3 Long-term Water Immersion
Haliburton et al. (1978) reported that 5-week immersion of four poly-
propylene woven fabrics in artificial seawater reduced the postimmersion
strengths by 6 to 32 percent. No explanation was given for the strength
losses, and the weight gain for the two fabrics with the greatest strength
loss was less than 2 percent.
Tests by Allen et al. (1982) did not reveal any reduction in strength
from immersion in saline water for 50 24-hr cycles of freezing and thawing.
Christopher (1983b) evaluated the performance of several installations in
which a polypropylene monofilament woven fabric was used beneath rip-rap for
shoreline erosion protection. After 10 years of exposure to alternating
cycles of salt water immersion and drying, samples of fabric were excavated
and tested. In most cases, there was less than a 20% decrease from the
strength of the new fabric, and in some cases only a 5% decrease or less was
noted.
2-45
-------
3.0 DESIGN OF FILTERS AND DRAINAGE SYSTEMS
3.1 Requirements for Conventional (Granular) Filters
Rules for the design of filters and drainage systems using granular
materials are well established and have been used successfully for many years.
These rules were originally proposed by Terzaghi (1982) and have been reevalu-
ated and elaborated on by many investigators. See, for example, Thanikachalam
et al. (1972), Sherard et al. (1984a) , and Sherard et al. (1984b), The rules
are based on the premise that to perform correctly as a soil filter, the
filter must retain the soil to be protected and be sufficiently permeable to
prevent buildup of hydrostatic pressure. In some applications, the granular
material acts as both a filter and a conduit for the fluid to be drained. The
criteria for sizing of a granular soil filter is based on the gradation of the
filter relative to that of the soil as follows
D filter
< 5 Equation 3-1
D of soil being drained
D filter
- . : < 25 Equation 3-2
D of soil being drained
where
DQ,. , D ,, , and D, ,. are the particle sizes of the material, of which
85, 50, and 15 percent by weight are smaller, respectively
For fine-grained soils such as silts and clays, as well as for sands and
coarser materials, the above criteria have been found to be conservative
(Sherard et al., 1984a).
For protecting fine-grained soils such as silts and clays, a sand filter
having
DIS filter ^ 0.3 mm Equation 3-3
has been shown to be conservative (Sherard et al., 1984b). Sherard states
that neither the plasticity nor the dispersiveness of the clay has a signi-
ficant influence on the filter criteria.
3-1
-------
In most applications, the granular material used as a filter does not in
itself have sufficient permeability to carry the flow quantities needed. The
flow capacity of trenches and blankets are therefore usually augmented by
a layer of coarse gravel and/or perforated or slotted drain pipe. To prevent
piping of the granular filter into the pipe, the following criteria have been
established (Cedergren, 1977b) (Department of the Army, 1978):
For slotted pipes: D50 fllter > Equation 3-4
slot width
For perforated pipes: 50 > Equation 3-5
hole diameter
In addition to a piping requirement, a permeability criterion is speci-
fied to assure that the filter is substantially more permeable than soil
being protected (Cedergren, 1977b). This is expressed as
D filter
Equation 3-6
D of soil being drained -
However, it can not be assumed that if the permeability criterion of Equa-
tion 3-6 is met that a drain has adequate flow capacity. When designing a
drainage system, it is essential to evaluate the potential inflows at all
points in the system and design the drain including selection of the drain
pipe to carry the expected flows based on seepage principles.
Figure 3-1 illustrates the use of conventional filter criteria in the
design of a graded filter for a ground-water interceptor trench. Note that as
a practical matter, the filter material must be specified as a range of pos-
sible gradations and that the criteria must be applied to account for the
variations in the allowable gradation range.
3.2 Requirements for Fabric Filters and Drains
In cases such as that illustrated in Figure 3-1 it is often cost effec-
tive to substitute a properly selected fabric for one or more of the compo-
nents of a conventional granular filter/drainage system. When used in such
applications, engineering fabrics must fulfill the same requirements imposed
on granular filters: the fabric must prevent piping of the soil to be drained
and remain sufficiently permeable over the life of the project to prevent the
buildup of hydrostatic pressures. Numerous approaches have been taken to
developing filter criteria for engineering fabrics. These have been sum-
marized by numerous authors, including Hoare (1982), Lawson (1982), and
Rycroft and Dennis Jones (1982). All criteria have some means of evaluating
the piping potential of fabrics, and attempt to assure adequate permeability
3-2
-------
FIGURE 3-1
DESIGN OF A GRADED FILTER FOR A GROUNDWATER INTERCEPTOR TRENCH
COMPACTED BACKFILL
MEETING FILTER
CRITICAL WITH RESPECT TO
FINE FILTER MATERIAL
FINE FILTER MATERIAL
SELECTED TO PREVENT
PIPING OF NATURAL SOIL-
(CURVE 2)
SLOTTED OR PERFORATED
COLLECTOR PIPE -
T
in t»
TED
^^
7/^///J7;
•
-s
" .•".*•
A
<7
P
< ^
-------
by measuring the permeability of the fabric or the hydraulic performance of
the fabric-soil system. In addition to the hydraulic requirements, fabrics
must also possess adequate strength to withstand the stresses associated with
installation and any subsequent stressing.
3.2.1 Hydraulic Requirements
The most widely known criteria in the United States for selection of
fabrics for filtration are those proposed by Calhoun (1972), whose work was
incorporated by the U. S. Army Corps of Engineers into a construction guide
specification for the selection of fabrics for filtration and erosion control.
The criteria for piping was based on evaluation of the fabric opening size as
determined by the EOS test described in Section 2, related to an empirical
criteria for sizing of holes in perforated pipe. Calhoun's criteria stated
the following:
a. Adjacent to granular materials containing 50 percent or less by
weight of material passing the No. 200 sieve and having little
or no plasticity:
(1) Doc of soil to be drained (mm)
oj
._. EOS (mm)
(2) Open area is not to exceed 40 percent.
b. Adjacent to soils having little or no cohesion and containing
more than 50 percent silt by weight:
(1) EOS is no larger than the opening in a No. 70 sieve.
(2) Open area is not to exceed 10 percent.
Calhoun also states that, where possible, one should use fabric with the
greatest open area allowed by the criteria. Also no fabric should have the
EOS smaller than the No. 100 sieve, and the percent open area should never be
less than 4 percent. These original recommendations were made when very
little nonwoven fabric was being used for filtration and drainage applica-
tions, and Calhoun's recommendations apply primarily to woven fabrics. The
percentage of open area, for example, can only be determined on fabrics with
distinct two-dimensional openings such as those found in woven fabrics. Sub-
sequent work by the U. S. Army Corps of Engineers at the U. S. Army Engineer
Waterways Experiment Station led to adoption of the gradient ratio test as a
means of evaluating both woven and nonwoven fabrics. As published in a
revised guide specification, the U. S. Army Corps of Engineers (Department of
the Army, 1977) criteria are based on the EOS and gradient ratio tests. To
satisfy the criteria,
a. For the particular soil-fabric combination being proposed
3-4
-------
Gradient ratio < 3
b. For fabric adjacent to soils containing 50 percent or less by
weight fines
D0_ of the soil to be drained (mm)
O-) .
EOS (mm)-
c. For fabric adjacent to all other types of soil the EOS
No. 70 sieve (mm) >; EOS _> No. 100 sieve (mm)
d. Filter fabrics should not be used for soils having gradations in
which 85 percent or more passes the No. 200 sieve.
e. When possible, it is preferable to specify a fabric with openings
as large as allowed by the criteria.
The U. S. Army Corps of Engineers criteria given above limit the range of
soils for which fabric can be used. The U. S. Forest Service, in a report by
Steward et al. (1977), presented filter criteria nearly identical to those
used by the U. S. Army Corps of Engineers without a limitation on the use of
fabric for soils with more than 85 percent of the particles passing the
No. 200 sieve.
Haliburton and Wood (1982) have substantiated the U. S. Army Corps of
Engineers gradient ratio criterion for evaluating the clogging potential of
soils under severe hydraulic conditions. In soils subject to internal erosion
(suffosion) or instability, fines are carried by flowing water through the
coarser particles, pass through the fabric and are carried away, or they build
up on (or in) the fabric causing clogging and pressure buildup behind it.
Haliburton and Wood found that as the amount of fines piping through the soil
increased, the gradient ratio increased slowly to a value of about 3 and then
increased rapidly, with small further increases in soil fines content.
Though the gradient ratio test provides a direct measure of fabric
performance with a given soil, the test is relatively time-consuming and
expensive, and it is soil-specific. In applications where only small flows
and low hydraulic gradients are involved, Haliburton et al. (1981) recommended
that the fabric be more permeable than the adjacent soil and that clogging
potential not be evaluated. Haliburton suggested use of a fabric with a
permeability at least 10 times greater than the permeability of the soil.
Bell and Hicks (1983), after an extensive review of test methods and use
criteria for geotextiles, proposed a set of recommendations for the use of
fabrics in filter applications. Their criteria are based on the EOS test,
fabric permeability, and the use of monofilament woven fabrics for severe
hydraulic conditions. Their recommendations are summarized as follows:
3-5
-------
a. To provide sufficient initial permeability
(1) k
geotextile ^ ,
ksoil
(2) Maximum allowable threshold gradient is to be considered for
very low gradients. Allowable threshold gradient is to be
selected by designer.
b. To provide confinement of the soil to be protected:
(1) EOS (in mm) < D0 of soil to be drained or .210 mm
OJ
(No. 70 sieve) > EOS > .149 mm (No. 100 sieve), whichever is
greater,
(2) Designer is to select a flexible fabric when soil surface is
rough but no specific requirements are given.
c. To resist plugging of geotextile and significant reduction of
permeability of system below initial geotextile permeability:
(1) For well-graded or uniform soil and clean water, a 10-percent
minimum open area is recommended for woven fabrics. No open
area recommendation is made for nonwoven fabrics.
(2) For gap-graded soil and/or dirty water, use monofilament
woven fabric with EOS > 6 times the average size of the fine
fraction or suspended solids is recommended. Fabric should
have a minimum of 10 percent open area.
(3) For soils having more than 85 percent finer than a
No. 200 sieve, an open area between 4 and 10 percent is
recommended for woven fabrics. No recommendation is made for
nonwoven fabrics.
From the above review it seems apparent that, at least in the United States,
most criteria for the selection of fabrics are based in whole or in part on
criteria originally proposed by the U. S. Army Corps of Engineers. These
criteria depend on certain specific test procedures described in Chapter 2 for
their validity. All the criteria are based on the principle that the geotex-
tile will always remain in contact with the soil to be drained, and that the
soil structure next to the fabric does not move. None of the criteria are
intended to resist loss of soil though the fabric openings in those cases
where soil can move freely next to the fabric. However, proper installation
procedures (described later), will prevent particle movement for all the
applications described in this handbook.
The recommended hydraulic requirements for filtration and drainage
applications in hazardous waste landfills appear in Table 3-1. These
3-6
-------
TABLE 3-1
RECOMMENDED CRITERIA FOR SELECTION OF GEOTEXTILES
FOR FILTRATION/DRAINAGE APPLICATIONS
I. Hydraulic Requirements
A. Gap-graded soils, soils having coefficient of uniformity, C > 20.
(1) Piping Resistance Requirement
EOS (in mm) < D0 of soil to be drained
— 03
For soil having D finer than the No. 70 sieve,
o_>
0.149 mm (No. 100 sieve) _< EOS (in mm) _< 0.210 mm (No. 70 sieve)
(2) Permeability/Clogging Resistance Requirement
Woven fabrics: percent open area > 10 percent
Nonwoven fabric: gradient ratio _< 3
B. All soils not covered by A, above.
(1) Piping Resistance
EOS (in mm) < D of soil to be drained
— oj
For soil having a D finer than the No. 70 sieve,
o_>
0.149 mm (No. 100 sieve) <_ EOS (in mm) _< 0.210 mm (No. 70 sieve)
(2) Permeability/Clogging Resistance Requirement.
k fabric > k soil
Alternate requirement (applicable to woven fabrics only)
Percent open area > 4
(continued)
Coefficient of uniformity, C = -—
3-7
-------
TABLE 3-1 (continued)
II. Physical Requirements
Property
Test
Tensile
strength
Elongation
at failure
Tear
resistance
ASTM D 1682 Grab test using CRE test-
ing machine operated at 305 mm
(12 in.) per minute; 25 mm
(1 in.) x 50 mm (2 in.) jaws.
ASTM D 1682 Grab test using CRE test-
ing machine operated at 305 mm
(12 in.) per minute; 25 mm
(1 in.) x 50 mm (2 in.) jaws.
ASTM D 1117 Trapezoidal Tear.
Puncture
resistance
Minimum Value
334 N (75 Ib)
in both
principal
directions
20 percent in
both
principal
directions
222 N (50 Ib)
in both
principal
directions
156 N (35 Ib)
Flexibility
ASTM D 3787, modified by replacing
the steel ball with an 8 mm diam-
eter steel rod having a hemispher-
ical tip.
No quantitative requirement. Fabric flexibility
should be considered with respect to the particular
installation and the need to maintain intimate
contact with soil to be protected. Use flexible
fabric when soil surface is rough. Use ASTM D 1388
to evaluate geotextiles.
III. Environmental Resistance Requirements
A. Fibers used in the manufacture of the engineering fabric shall
consist of a long-chain synthetic polymer consisting of at least
85 percent by weight propylene, ester, or vinylidene-chloride. If
any polymers other Chan those specified are proposed, they must meet
the requirements set forth in Table 3-2.
B. The engineering fabric shall be of a composition resistant to
ultraviolet light and weathering such that it shall retain at least
90 percent of its initial tensile strength after 100 hr of exposure
in an Xenon- Arc Weatherometer, as specified in ASTM D 4355.
C. Fabric placed in any location where it may potentially be subjected
to contact from a chemical environment other than that of natural
soil, shall be evaluated for its resistance to the anticipated
chemicals to which it may come in contact.
3-8
-------
TABLE 3-2
ENVIRONMENTAL RESISTANCE REQUIREMENTS FOR GEOTEXTILES
Treatment
Test Method
Alkali treatment
Fuel immersion
Acid treatment
Low temperature strength
High temperature strength
Oxygen pressure
Freeze-thaw
Weatherometer
Long-term immersion
Low-temperature brittleness
Weight change in water
Special
Specialb
Special13
ASTM D 1682 at -18° C,
ASTM D 1682 at 82° C.
ASTM D 572
ASTM C 666
ASTM G 23
Special
ASTM D 746
CRC-C-575
a.
Required Result
90 percent
90 percent
85 percent
85 percent
80 percent
90 percent
85 percent
65 percent
80 percent
No failures at minus
51.1° C (60° F)
Less than 1.0%
Ratio of strength after treatment to strength for untreated fabric specimens
tested according to ASTM D 1682, grab test using CRE testing machine
^operated at 305 mm (12 in.) per minute and 25 mm x 25 mm jaws.
The test methods are special U. S. Army Corps of Engineers tests. They are
described in Calhoun (1972).
recommendations are based on the criteria discussed above and on the experi-
ences of U. S. Army Corps of Engineers personnel in the use of fabrics in
filtration and drainage. The recommendations are divided into two categories.
Category A is for severe applications where the possibility exists for move-
ment of soil fines in suspension. Category B is for all other applications
where internal migration of fines will not take place. In both categories,
allowance is made for the reduction in initial fabric permeability that occurs
when a fabric is implanted in soil.
3.2.2 In-plane Permeability (Transmissivity)
Certain engineering fabrics and specially designed composite structures
can be substituted for granular drainage material and drainage pipe. When
3-9
-------
these materials are considered for use, the same information about expected
flow rates or regulatory requirements for flow capacity must be known as if a
conventional material were used. These materials must also fulfill the
requirements for filters discussed in previous paragraphs. Though thick-
needle punched fabrics and composite structure drainage panels and drainage
grids have been used in several sites, no history of performance exists for
materials in this application as does for fabrics in filtration applications.
Selection of these materials for use as drains should be made with caution and
only after performing transmissivity tests of the type described in Chapter 2.
These tests must demonstrate that the long-term flow capacity under antici-
pated field loads and in contact with the types of materials expected at the
site is adequate to meet regulatory requirements. Thus if a fabric-covered
drainage grid will be in contact with soil on one side and a flexible syn-
thetic membrane on the other side, tests should be performed with these mate-
rials in contact with the drainage grid under anticipated maximum field
loading. Considerations should also be given to creep of synthetic materials
and reduction of transmissivity over time.
3.2.3 Fabric Physical Requirements
Based on the experimental work by Calhoun (1972) and subsequent field
experience, the U. S. Army Corps of Engineers (Department of the Army, 1977)
guide specification for filter fabric specifies strength values for use of
fabric in both erosion control and subsurface drainage/filtration applica-
tions. The requirements for subsurface drainage require a tensile strength
(grab method) of 445 N (100 Ib), puncture strength of 178 N (40 Ib) (ASTM
D 3787 modified as described in Chapter 2), and an abrasion resistance of
100 N (22-1/2 Ib) (ASTM Method D 3884). Bell and Hicks (1983) propose minimum
mechanical properties for fabric as follows: minimum tensile strength, 334 N
(75 Ib) (ASTM 1682, grab method); minimum failure elongation, 20 percent
(strain from ASTM D 1682), and minimum tear resistance, 222 N (50 Ib)
(trapezoidal tear, ASTM D 1117).
Haliburton et al. (1981) proposed strength values similar to those recom-
mended by the U. S. Army Corps of Engineers, with the addition of a burst
strength requirement of 1,379 kPa (200 psi) and a reduction of puncture
strength to 156 N (35 Ib) and abrasion resistance to 89 N (20 Ib).
The recommended minimum physical requirements for fabrics used in filtra-
tion and drainage applications are given in Table 3-1. The values given are
based on a consensus of the recommendations given above.
3.2.4 Environmental Resistance Requirements
General environmental resistance requirements for fabrics to be used in
filtration and drainage applications are given in Table 3-1. Requirements for
chemical resistance will be highly site-specific. Fabrics used in the cover
layers of a solid waste landfill will not be subjected to any more than normal
soil organisms and chemicals, but fabrics used in leachate collection systems
or interceptor trenches may be subjected to high concentrations of chemicals.
Compatibility tests are recommended on a site-specific basis using candidate
fabrics to determine suitability. In addition to any site-specific chemical
3-10
-------
resistance requirements, any geotextile made from polymers other than
polypropylene, polyester or polyvinylidene-chloride should meet the general
environmental resistance requirements in Table 3-2.
3.3 Use of Fabric in Subsurface Drains
3.3.1 Fabric Selection Criteria
The fabric selection criteria for underdrains, interceptor drains, and
drainage blankets are essentially the same. While the filtration and strength
requirements would remain the same for each, the requirement for in-plane flow
capacity would depend on whether the fabric or composite were being used as a
drain as well as filter for the surrounding material. As stated previously,
the chemical resistance requirements depend on site-specific factors as well
as the type of application.
3.3.2 Interceptor Drain and Collector Drain Construction Procedures
Interceptor drains are normally placed at three locations in waste con-
tainment facilities. They may be placed around the periphery of a waste site
to intercept ground water and prevent its entering a contaminated area.
Interceptor drains may be built into a seepage cutoff wall to intercept
leachate or contaminated ground water and prevent its buildup within the site,
and they may be placed in a slope to intercept seepage and prevent its exiting
at the surface in an uncontrolled manner and causing saturated unstable con-
ditions. Collector drains are built as part of a leachate collection system
to speed the flow of leachate to a central sump area or as part of a multi-
layered cover system to collect and discharge rainwater that has infiltrated
the top soil layer.
Computation of expected inflow volumes, drain size, outlet pipe spacing,
location of trench, and other hydraulic parameters are beyond the scope of
this manual.
The configuration of a typical collector trench, interceptor trench, and
side-slope seepage cutoff trench is illustrated in Figure 3-2. In each of
these cases, the fabric is selected to protect the surrounding soil, and the
granular material placed in the trench should preferably be open-graded high-
permeability drainage material to facilitate drainage. The high-permeability
of open-graded drainage material may allow a considerable reduction in the
physical dimensions of the underdrain and may eliminate the need for a
collector pipe for drainage distances on the order of 9 to 30 m (30 to 100 ft)
according to Steward et al. (1977).
The practice of wrapping drain pipe in fabric and using a drainage sand
to protect the surrounding soil is not a preferred practice and should be
avoided. This practice reduces the surface area through which seepage takes
place through the filter fabric, thus exacerbating any reduction in perme-
ability that may occur in the drainage system. When fine drainage material is
used in the trench, the benefits of high-flow capacity are to a great extent
lost, as fine drainage material such as concrete sand is much less permeable
than open-graded gravel. Finally, wrapping collector pipes may make drainage
3-11
-------
FIGURE 3-2
INTERCEPTOR AND COLLECTOR TRENCH CONFIGURATIONS
GEOTEXTILE-
'.'0'.
BACKFILL
a. GROUND WATER OR LEACHATE INTERCEPTOR TRENCH
GROUNDWATER
SEEPAGE
BACKFILL
b. GROUNDWATER SEEPAGE INTERCEPTOR TRENCH
WASTE
RAINAGE GRAVEL .
GEOTEXTILE
IMPERMEABLE
MEMBRANE
COLLECTOR PIPE (OPTIONAL)
c. COLLECTOR TRENCH AS PART OF LEACHATE COLLECTION SYSTEM
3-12
-------
system maintenance such as high-pressure-back flushing impossible because of
the possibility of damaging the fabric from a direct high-pressure jet. The
experiences of several authors substantiate the recommendation for avoiding
the practice of wrapping the collector pipe with fabric (Haliburton et al.
1981; Wolf and Christopher, 1982).
The construction procedure for lining an interceptor drain is illustrated
in Figure 3-3. For collector drains in leachate collection systems, the
procedure is essentially the same except that the fabric, instead of being
folded over as shown in Figure 3-3d, is fixed in the open, laid-back position.
Fabric installed as part of the leachate collection blanket is lapped over
this fabric at least 0.3 m (12 in.), and drainage material is placed to grade
over the trench and the surrounding area.
FIGURE 3-3
GENERAL CONSTRUCTION PROCEDURE FOR INTERCEPTOR TRENCH DRAINS
MAIL OR WEIGHT WITH ROCKS, ETC.—-^
I
•SMOOTH
SIDES
GRAVEL AS
REQUIRED TO
MAINTAIN GRADE
AND PROVIDE
BEDDING FOR PIPE
\
1
\
• —
•o
fe^S&
N
/
4\ FABRIC PLACED
A\ LOOSE TO
> ALLOW
•-CONFORMING
WITH
EXCAVATION
a. FORM CLEAN EXCAVATION
b. DRAPE FABRIC IN TRENCH
DROP DRAINAGE MATERIAL
AVOID IMPACTING
SIDES
\
1
0 o
oc
0 0
ffiVo*
°o^v£
/
i
OVERLAP
FABRIC Nl
COMPACTED BACKFILL
i
c. FILL WITH AGGREGATE
d. CLOSE TOP OF TRENCH
3-13
-------
3.3.3 Drainage Blanket Construction Procedures
Drainage blankets are encountered in land waste disposal operations
either in leachate detection/collection systems or as a drainage layer in
multilayered cover systems. In either case, engineering fabric is used to
envelop the drainage layer and prevent surrounding waste solids or soil from
infiltrating and destroying the flow capacity of the drainage layer.
The placement of filter fabric in the construction of leachate collection
is relatively straightforward. The fabric is unrolled over the surface to be
covered and the seams are completed by either field sewing or by overlapping a
minimum of 0.3 m (12 in.). The configuration of a multilayered cover system
in which fabric is used as a filter is shown in Figure 3-4.
In some instances it is necessary to place a drainage layer on a rela-
tively steep slope. In these applications, it will normally be necessary to
weigh the fabric at the top of the slope and stake the fabric at intervals
along the slope to prevent slippage and wind lift.
FIGURE 3-4
USE OF FABRIC FOR FILTRATION IN A MULTILAYERED COVER SYSTEM
FILTER FABRIC LAYERS
\
3.3.4 Prefabricated Drainage Systems
As described in Chapter 1, a number of recently marketed products have
the capability to provide both filtration and drainage without the need for
use of drainage aggregate. The products are variously known as prefabricated
fin drains or prefabricated drainage systems. Examples of such systems appear
in Figures 3-5 and 3-6. When these drainage systems are used as interceptor
trenches, an impermeable synthetic liner can be attached to one side of the
panel during manufacture, providing an added barrier against ground-water/
contaminant leachate movement. When used against retaining walls, these
systems provide the drainage necessary to prevent possible tipping or failure
of the wall as a result of the buildup of hydrostatic pressure against the
wall. The prefabricated drainage panels substitute for a granular drainage
aggregate layer that would ordinarily be required against the wall to prevent
such pressure buildup.
In the design of a subsurface drainage system using prefabricated drain-
age panels, the filtration properties of the panel's outer layers must fulfill
3-14
-------
FIGURE 3-5
PREFABRICATED DRAINAGE PANEL INTERCEPTOR/CUTOFF TRENCH DRAIN
-LOW PERMEABILITY BACKFILL
SECURING PIN-
OPTIONAL SYNTHETIC
IMPERMEABLE MEMBRANE-
DRAINAGE PANEI
r
w/,
COMPACTED NATURAL SOIL
OR SAND BACKFILL
GROUNDWATER FLOW
-FLOW INSIDE PANEL
PVC COLLECTOR PIPE
SLOTTED FOR DRAINAGE PANEL
FIGURE 3-6
PREFABRICATED DRAINAGE PANEL TO RELIEVE HYDROSTATIC PRESSURE AGAINST
RETAINING WALL
ENGINEERING FABRIC-
CONC. WALL-
COLLECTOR
PIPE-
'S
;•' <-DRAINAGE PANEL
•.^ OR GRID
-LOW PERMEABILITY BACKFILL
^^\
NATURAL SOIL
3-15
-------
the same criteria as required for other filtration/drainage applications. The
potential volumes of water or leachate that must be handled by the drainage
system must be determined and compared with the flow capacity of the type of
prefabricated drainage system under consideration. The accumulated volume of
water or leachate carried to the discharge pipe cannot exceed the prefabri-
cated drainage systems flow capacity or the flow capacity of the collector
pipe, whichever is smaller.
The flow capacities of drainage panels and grids are dependent on the
magnitude of the normal stress applied to them under long-term loading.
Therefore the designer must calculate the highest level of stress expected on
the panel and must have test data verifying the particular drainage system's
ability to maintain adequate flow rates under long-term stressing at the
calculated normal pressures. Details of drainage panel collector pipe
connections are shown in Figure 3-7.
3.3.5 Strip Drains - Case History
Strip drains are inserted by means of special equipment into soft sedi-
ments to accelerate the consolidation of these materials. The theoretical
treatment of strip drains for consolidation is similar to the theoretical
analysis for sand drains and is amply treated in the literature. See, for
example, Kjellmann (1948), Risseeuw and van den Elzen (1977), Hansbo (1981),
and McGown and Hughes (1981). Normally, strip drains are inserted vertically.
However, strip drains might be installed horizontally in soft sediment con-
tainment areas to accelerate the consolidation of such sediments by providing
intermediate drainage layers while additional material is being deposited.
Though to our knowledge this has not been tried at a waste disposal site, a
similar application proved feasible for a coal refuse embankment (Thacker and
Schad, 1983).
In the mining and power industries, cohesive soil and/or cohesive wastes
are used to construct dams to retain a variety of wastes. As with any embank-
ment composed of cohesive material, high pore-water pressures created during
construction can lead to instability and failure of the embankment if not con-
trolled. The embankment and the fine sediments behind the embankment are
often placed built in stages, allowing excess pressures to dissipate between
construction stages. Or, as in the case of one coal refuse disposal site in
eastern Kentucky, pore-pressure dissipation was accelerated by installation of
strip drains. The layout of the strip drains is shown in Figure 3-8. Fig-
ure 3-9 shows the increased rate of pore-pressure dissipation for the embank-
ment in which the strip drains were installed. Beyond the advantages of
expediting construction of the embankment and accelerating drainage of soft
waste sediments behind the dam, the increased rate of consolidation allows
faster placement of waste material. This last advantage applies to waste
ponds where the ongoing deposition of waste requires that the wastes already
placed be consolidated as rapidly as possible to allow room for additional
waste.
3-16
-------
FIGURE 3-7
EXAMPLES OF DRAINAGE PANEL COLLECTOR PIPE CONNECTIONS (Hunt, 1982)
OJ
I
I
fin drain
laid against
trench face
from which
water ig expectefi
Plastic
studs
Granular pipe-
bedding material
pipe
— fin drain
staple
fabric filter
Porous or
perforated pipe
Granular pipe-
bedding material
fin drain
Porous or
perforated pipe
Granular pipe-
bedding material
-------
FIGURE 3-8
LOCATION OF HORIZONTALLY PLACED STRIP DRAINS IN COAL REFUSE
EMBANKMENT (Thacker and Schad, 1983)
800
z- 1700
g
< 1600
LJ
_i
m 1500
i i
REFUSE IMPOUNDMENT
120'J"" "I CREST ELEV. 1790'
I I
COARSE REFUSE EMBANKMENT
^^•.••.-.•:--. • .•••-.-•.^hz
-(/ •-—-^.//_J.- .- .'. -. -. ;
H STRIP DRAINS '-^-•-^y
NATURAL GROUND SURFACE
ROCKFILL UNDERDRAIN-
i i i i
6+00 8+00 10+00 12+00
STATION, FT
4+00
16+00
FIGURE 3-9
MEASURED RELATIONSHIPS BETWEEN TIME AND DEGREE OF PORE PRESSURE
DISSIPATION WITHIN FINE REFUSE DEPOSITS WITH AND WITHOUT
SYNTHETIC STRIP DRAINS (Thacker and Schad, 1983)
I
WITHOUT
STRIP DRAINS
T
WITH
STRIP DRAINS
-t
200 300
TIME, DAYS
400
3-18
-------
4.0 GAS VENTING
4.1 Introduction
When a liquid impoundment is constructed using synthetic membrane liners,
an important design and construction consideration is prevention of ballooning
of the membrane from gases formed beneath it. These gases most commonly
result from decomposition of organic matter in the soil beneath the impound-
ment, but these may result from such other factors as acid leaking through
holes in the membrane liner and reacting with soil minerals and evolving
gases.
The use of thick fabrics with significant in-plane permeability as a
venting layer between the subgrade soil and the synthetic liner has been
practiced for over a decade (Giroud, 1982). These fabrics also often provide
some puncture protection for the liner and a clean work surface for liner
seaming during installation.
If gases generated within landfills by decomposition of organic matter or
volatilization of chemicals are not dissipated in a controlled manner, several
problems could occur in the cover system. Methane and other gases could,
under sufficient pressure, find pathways through a clay cap, killing the vege-
tative cover near the leak and possibly causing dangerous concentrations of
explosive and poisonous gases. If a synthetic membrane is used as part of a
cover system, pressure buildup beneath the membrane could cause the gas to
migrate around the periphery of the landfill, producing dangerous concentra-
tions at unexpected locations such as the basements of nearby buildings.
Thus a safe and controlled means of venting these gases must be provided in
landfills where gas generation is possible. Thick fabric grids or meshes
having sufficient gas transmissivity can provide the same controlled venting
of gases at solid waste landfills as they do beneath liquid impoundments.
4.2 Current Practice
According to Giroud and Bonaparte (1984) there are no design procedures
available for gas drainage systems. However, through trial and error, suit-
able materials and procedures for construction of gas drainage systems have
been developed. The materials suitable for use in these systems have been
categorized by Giroud and Bonaparte as:
a. Needle-punched, nonwoven fabrics having thicknesses from 2
to 5 mm (80 to 200 mils) or more
b. Mats 10 to 20 mm (3/8 to 3/4 in.) thick
c. Nets or grids approximately 5 mm (1/4 in.) thick
4-1
-------
d. Corrugated, waffled, or other plates covered with fabric
10 to 20 mm (3/8 to 3/4 in.) thick.
According to Kays (1977), if gas evolution is anticipated for an
uncovered pond or liquid impoundment, the bottom slope of the impoundment
should be about 3 percent, and a continuous pervious underdrain should cover
all bottom and side slopes. Gas vents should be placed high on the side
slopes just below the top of the berm. The vent spacing may vary, but a spac-
ing of 15 m (50 ft) is recommended. Examples of typical vent designs are
shown in Figures 4-1 and 4-2. These vents can be used with a conventional
sand undrain or a geotextile drain.
FIGURE 4-1
MOLDED HYPALON3 AIR/GAS VENT ASSEMBLY (Burke Rubber Company, n.d.)
r—OPENINGS IN VENT TO BE HIGHER THAN
TOP OF BERM OR OVERFLOW LIQUID LEVEL.
AIR/GAS VENT ASSEMBLY,
MOLDED HYPALON WITH
STAINLESS STEEL PERFORATED
SCREEN.
HYPALON
LINER.
- APPROX. 6"
-GEOTEXTILE OR
DRAINAGE COMPOSITE
SPECIFY SLOPE RATIO OF MOLDED
SKIRT TO MATCH POND SIDE SLOPE
BOND SKIRT OF
VENT TO LINER
ALL AROUND WITH
BODIED SOLVENT
ADHESIVE.
GAS FLOW
Hypalon is a registered trademark of Du Pont for chlorosulfonated
polyethylene.
4.3 Fabric for Venting Beneath Liquid Impoundments
4.3.1 Case History 1
As an example of how synthetic materials may be used for gas venting in a
liquid impoundment, Giroud and Bonaparte (1984) provide the following account:
4-2
-------
11"
FIGURE 4-2
HALF-TUBE AIR/GAS VENT ASSEMBLY (Burke Rubber Company, n.d.)
8i« i
L
rr~~n
i ii
i.^l
' 11
~M
U
U" DIA. HOLE PUNCHED IN
CENTER OF 8i" x 11" PIECE.
5" x 6" CAP STRIP OF
45 MIL, 5-PLY, REINFORCED
HYPALON
8i" x 11" PIECE
SAME MATERIAL AS ABOVE
PVC PIPE BONDED TO CAP STRIP
WITH BR-700 CONTACT CEMENT
BONDED AS SHOWN
SPLIT If DIA. PVC PIPE, 6" LONG
AIR/CAS VENT
• GEOTEXTILE OR
DRAINAGE COMPOSITE
PLACE VENT HIGHER THAN MAXIMUM
LIQUID LEVEL AT OVER-FLOW
CONDITIONS.
2" MINIMUM
SECTION A-A
GAS FLOW
4-3
-------
A plastic net has been used to drain air
entrapped beneath the geomembrane lining a large
evaporating pond 400 by 235 m (1300 by 770 ft),
containing uranium mine tailings and sulfuric acid.
From past experience in the area, it was feared that
air entrapped beneath the geomembrane during its
installation would be pushed towards a high point of
the pond bottom by the pressure of the liquid during
the first filling, thus locally uplifting the geo-
membrane and forming a bubble. The large size of the
quasi-horizontal bottom of the pond made it impracti-
cal to eliminate all high spots. (A 100 mm (4-in.)
high spot is sufficient to foster air accumulation
during filling of the pond).
In ponds previously built in the area, plastic
pipes, running every 10 m (33 ft) along the side
slopes of the pond and connecting to a sand layer
beneath the geomembrane, had been used for draining
entrapped air. Slope deformation resulting from the
properties of the locally available fill material
caused some of the pipes to protrude from the slope,
thereby inducing excessive concentrated stresses in
the geomembranes. It was decided to use nets instead
of pipes in the subsequent pond, because their flexi-
bility would allow them to follow slope deformation
without damaging the geomembrane.
Plastic net strips 1.63 m (64 in.) wide were laid
out according to [Figure 4-3a]. Air is collected by a
strip running at the periphery of the pond bottom and
by additional strips connecting high spots of the
bottom to the peripheral strip. Escape of collected
air is through plastic net strips running along the
side slopes of the pond and the crest of the dike.
Center-to-center spacing between strips on the slopes
is 20 m (60 ft) along the lower half of the pond and
10 m (30 ft) along the upper half, where more air is
expected to be collected. Since no method of design
is available for gas drainage, spacing has been chosen
similar to the spacing of pipes used in previous
ponds.
The plastic net strips on the side slopes were
part of a laminated structure composed of a poly-
ethylene low-permeability sheet, a plastic net, and a
geotextile [(Figure 4-3b)]. The polyethylene sheet
prevents erosion of the slope if the geomembrane leaks
and liquid runs down the slope. The geotextile,
placed on the plastic net, prevented it from being
clogged by dust and blown sand prior to geomembrane
4-4
-------
FIGURE 4-3
USE OF LAMINATED STRIPS FOR GAS DRAINAGE IN A GEOMEMBRANE-
LINED URANIUM MINE TAILINGS EVAPORATING POND: (a) LAYOUT
OF THE 1.63 m (64 in.) WIDE STRIPS; (b) CROSS SECTION.(*)
CONNECTION BETWEEN PERIPHERAL STRIP AND SIDE-SLOPE STRIP
(Giroud and Bonaparte, 1984)
r
Peripheral laminated strip
Side-slope laminated strip
Additional laminated strip
Pond bottom
high spot
]
X'
(Not to scale)
(a) Plan view
(b) Section X - X1
—— Geomembrane
Legend: Geotextile
Laminated strip
4-5
-------
placement. The laminated structures at the pond bot-
tom are geotextile/plastic net/geotextile.
The pond was first filled in 1982 and no uplift
has been observed since.
4,3.2. Case History 2
Another example of the use of engineering fabric to provide gas venting
can be found in the construction of Uranium mill tailings ponds (Baldwin,
1983). In this case, the Uranium mill tailings ponds were to be constructed
on lime-bearing soil. Any puncture in the membrane during use of the pond
would allow the acid pond liquid to percolate into the soil, causing the gen-
eration of gas. This gas would cause the membrane to form "whales" or large
uplifted sections. To combate the gas buildup in the event of a leak in the
liner, a 2.8-mm- (110-mil-) thick, needle-punched fabric was installed between
the membrane and the soil subgrade. Tests were performed by the fabric manu-
facturer to assure the owner that the fabric had sufficient gas transmissivity
under expected pressures with full ponds. Any gases generated were vented to
atmosphere through vents placed on 7.6-m (25-ft) centers along the top of the
embankment.
4.4. Gas Venting of Landfills
A discussion of the need for and approach to gas venting is available in
Remedial Action at Waste Disposal Sites, (U.S. Environmental Protection
Agency, 1982). Though no rational design procedures exist for the selection
of geotextiles or other drainage material for gas venting, experience has
shown that the heavy-needled fabrics, grids, and mats are capable of relieving
gas pressure beneath liquid impoundments and should be equally effective for
releasing gas pressure beneath solid and hazardous waste covers. Where waste
fill is of such permeability that gases can migrate easily within a waste
fill but are prevented from moving laterally out of the fill by low-permea-
bility soil or a synthetic membrane liner, atmospheric venting at the top of
the fill may be all that is necessary to control the effects of gas genera-
tion. In this case, heavy needle-punched, nonwoven fabrics, fabric-covered
grids, and fabric-covered meshes could substitute for pipe vents installed
horizontally near the surface in the fill. This gas-transmitting layer would
be vented to the atmosphere through risers extending from the gas-venting
layer through the cover layers.
In the absence of a field-validated procedure for evaluating the effec-
tiveness of the various drainage materials, it is recommended that one of the
fabric-covered grid or mat-type products be used for gas venting. These pro-
ducts have substantially greater transmissivities than needle-punched, non-
woven fabrics. If a needle-punched fabric is used, it is recommended that the
fabric thickness be at least 2 mm (79 mils) when compressed under a pressure
equal to the anticipated weight of the cover material.
If anticipated rates of gas generation are known, transmissivity tests
can be performed on the material being considered, using anticipated field
loads and gas pressures to verify that gas transmissivity is adequate.
4-6
-------
A geotextile vent layer should be located as carefully as a gravel
drainage trench or blanket would be located with regard to adequate drainage
of liquid away from vents and placement of drainage layers in locations of
greatest gas generation.
Vents of the mushroom type (similar in configuration to that shown in
Figure 4-1) or the inverted "U" shape should be satisfactory. These may be
made from plastic or noncorroding metal, and there should be flanged at the
lower end for stability and to distribute pressure over the venting material.
When vents are used in conjunction with a synthetic membrane, special precau-
tions must be taken to assure that the opening in the membrane is sealed
around the vent pipe.
Field placement of the material types should include overlapping of ends
by at least 0.3 m (12 in.) and use of multiple thicknesses of material beneath
vent flanges to reduce the chance that uneven loading from the vent flange
will reduce the flow capacity of the drainage material.
Peripheral vent trenches used to control lateral gas migration could be
lined with geotextiles. This step prevents loss of trench effectiveness by
preventing mixing of the trench drainage gravel with the finer surrounding
soil. The trench could be lined with fabric (Figure 4-4) or a drainage panel
(Figure 4-5). Fabric selection criteria should be the same as those given in
Chapter 3 for other filtration applications.
FIGURE 4-4
GAS INTERCEPTOR TRENCH USING GEOTEXTILE TO LINE TRENCH
GAS VENT
GAS
MOVEMENT
GEOTEXTILE
4 '
• -4 .
£
4 ' '
-TRENCH COVER
USING EXCAVATED
BACKFILL
DRAINAGE GRAVEL
4-7
-------
FIGURE 4-5
GAS INTERCEPTOR TRENCH USING DRAINAGE PANEL
GAS VENT
SLOTTED PIPE WITH
GEOTEXTILE WRAPPED
OVER TOP
BACKFILL USING
EXCAVATED SOIL
DRAINAGE PANEL
4-3
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5.0 EROSION CONTROL
5.1 Introduction
Historically, engineering fabric design criteria and construction con-
cepts were devised for coastal and riverbank protection. These design con-
cepts were later extended to surface runoff and overland erosion protection.
In landfill cover protection, erosion most commonly occurs in sheet form when
vegetative cover is inadequate or in localized areas where rainwater runoff
concentrates in surface depressions, swales, and ditches (Lutton, et al.,
1982). If the soils present at a landfill are primarily silts and fine sands,
erosion leads to deep gullying even when relatively flat slopes are used. One
of the most serious consequences of erosion at landfills is the removal of
cover soil, which leads to exposure of synthetic membrane covers with conse-
quent deterioration from ultraviolet light exposure or mechanical damage from
abrasion or vandalism.
Through efforts to stabilize streambanks, drainage ditches, and slopes
with layers of stones or riprap (broken rock), it was discovered that a bed-
ding layer of cohesionless material between the natural soil surface and the
cover stone resulted in a substantial performance improvement. When properly
sized with a gradation between that of the natural soil and the cover stone,
the bedding layer acted as a filter, allowing seepage out of the slope and
preventing the fine slope soil from eroding. It also provided support to the
cover stone, preventing it from sinking into the natural slope soil.
However, to perform satisfactorily, the bedding layer for slope protec-
tion had to satisfy the granular filter criteria in Chapter 3.
In general, only finer soils of little or no cohesion (such as fine
sands, silty sands, and silts) prove to have a significant erosion potential.
Unless water velocities are very high, gravels are resistant to water trans-
port, and clays usually have sufficient cohesion to resist surface erosion.
The exception to this is dispersive clays.
Gibbs and Holtz (1962), in research for the U. S. Bureau of Reclamation,
developed a relationship among liquid limit, plasticity index, and erosion
resistance, that quantified types of low-cohesion soils subject to erosive
behavior. These relationships are shown in Figures 5-1 and 5-2. Haliburton
et al. (1975) investigated the erosion piping resistance for dispersive clays
and found that the relationships developed by Gibbs and Holtz were not valid
for dispersive clays. However, recent research by Sherard et al. (1984b) has
revalidated the effectiveness of conventional granular filter criteria for
retaining dispersive soils and found the conventional criteria to be adequate.
Thus it seems reasonable that fabric filter criteria derived from these
principles would also be valid.
5-1
-------
FIGURE 5-1
POTENTIAL SOIL-EROSION RESISTANCE AS A FUNCTION OF DRY DENSITY
AND ATTERBERG LIQUID LIMIT (Gibbs and Holtz, 1962)
LL
O
GL
HI
a
>
cc
0
cc
^
H
LINES OF 100%
SATURATION
SPECIFIC GRAVITY
SPECIFIC GRAVITY
2.70
2.60
10 20 30 40 50 60 70 80 90
LIQUID LIMIT, %
EXPLANATION
SOILS WITH HIGHEST
RESISTANCE TO EROSION
- INTERMEDIATE SOILS
SOILS WITH LOWEST
RESISTANCE TO EROSION
5-2
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FIGURE 5-2
RELATIONSHIPS BETWEEN SOIL ATTERBERG LIMITS AND EXPECTED
EROSION POTENTIAL (Gibbs and Holtz, 1962)
50
40
x
ID
G
E 30
I 20
C/)
10
POSSIBLE EXPANSIVE
CHARACTERISTICS
SUGGESTED MAJOR
10 20 30 40 50 60 7Q
LIQUID LIMIT
80
EXPLANATION
HIGHEST RESISTANCE TO EROSION
SLIGHT EROSION EXPECTED
MODERATE EROSION EXPECTED
LOW RESISTANCE TO EROSION
5-3
-------
For the following discussion of erosion control measures using engineer-
ing fabric it is assumed that the soil has already been identified by observa-
tion, laboratory test, or other evaluation criteria to be susceptible to ero-
sion. Methods for calculating expected flow volumes, velocities, wave
heights, and other hydraulic data needed in preparation for a complete design
are assumed to have been determined by other means and are not discussed in
this manual. Detailed information on these parameters is available elsewhere
(Department of the Army, 1970, 1971).
5.2 Fabric Selection Criteria
5.2.1 Hydraulic Requirements
Hydraulic performance requirements for fabric used in erosion control
are essentially the same as the criteria used in Chapter 3 for selection of
fabric for filtration applications. Recommended fabric selection criteria are
given in Table 5-1.
5.2.2 Physical Requirements
The U. S. Army Corps of Engineers has developed considerable experience
with the placement of protective cover stone on engineering fabric. The
current U. S. Army Corps of Engineers guide specification (Department of the
Army, 1977) for the selection and placement of engineering fabric in erosion
control applications recognizes that the greatest stressing that engineering
fabric will undergo is during installation. Their specification states:
All fabric can be damaged if stone is dropped on
it from a height greater than 0.9 m (3 ft). Some
fabric can be damaged with lesser drop heights. When
stone is heavy and angular it may cause punctures in
fabric even if dropped from a height of 0.3 m (1 ft.).
Bell and Hicks (1983) summarize their experience with the placement of armor
stone on engineering fabric by recommending that for medium-duty applications
(which includes armoring to protect against wave heights up to 1.2 m, or 4 ft)
a bedding layer be placed between the fabric and the armor units. They
recommend that armor units not be dropped more than 0.9 m (3 ft) onto fabric
protected by a bedding layer. For light-duty applications where no separate
bedding layer is used, they recommend that the armor units be dropped no more
than 0.6 m (2 ft).
Note that the strength requirements for fabric recommended by Bell and
Hicks for erosion control are less than half the strength requirements
recommended by the U. S. Army Corps of Engineers guide specification. Neither
the Corps of Engineers nor Bell and Hicks place any specific limitation on the
size of stone to be placed on the fabric. From the foregoing evaluations, it
is recommended that the strength requirements for fabrics used for erosion
control be grouped into two categories:
5-4
-------
Service category A includes applications in which
riprap or other armor units are dropped directly on
the fabric from heights no greater than 1 m (3 ft),
provided that the underlying soil is sand or finer.
If the underlying soil is gravelly, the armor units
should not be dropped onto the fabric unless field
tests are performed at the site to ascertain a maximum
drop height that will preclude damage to the
geotextile.
Service category B includes applications in which
a bedding layer is placed between the fabric and the
riprap or other armor units and the armor units are
dropped onto the bedding layer from heights no greater
than 0.9 m (3 ft). The underlying soil shall be sand
or finer. If the underlying soil is gravelly, the
armor units shall not be dropped onto the fabric
unless field tests are performed at the site to
ascertain the maximum drop height which will preclude
damage to the geotextile.
The strength requirements for each service category are given in
Table 5-1. In addition to the physical requirements listed in the table,
consideration should be given to the flexibility of the fabric and its coeffi-
cient of friction with respect to the underlying soil and the bedding material
or armor. One should consider the possibility that the fabric will slide down
the slope while it is being placed or that the bedding layer or armor will
slide on the fabric, particularly on slopes steeper than IV on 3H. Trials may
have to be performed before fabric selection to establish a flexibility and/or
coefficient of friction requirement for the intended application.
5.2.3 Environmental Resistance Requirements
In the typical erosion control applications in hazardous waste landfills,
the environmental resistance requirements will be the same as those discussed
for fabrics used for filtration applications. However, the potential for
deterioration and eventual failure of the fabric from exposure to ultraviolet
radiation is greater in erosion control applications where a bedding layer is
not used or where the possibility exists for eventual loss of the protective
cover of smaller stone or bedding material. At the present time there is not
enough information to predict the long-term performance of fabrics exposed to
ultraviolet radiation. However, monofilament woven fabrics should have the
most resistance to degradation and should be used where extended exposures are
likely.
5.3 Protection of Waste Covers, Drainage Channels, and Drainage Outlets
5.3.1 The Erosion Problem
Though it is normally desirable for aesthetic and economic reasons to
vegetate landfill cover slopes and surface drainage channels wherever possi-
ble, there are nevertheless situations when vegetative cover is not adequate
5-5
-------
TABLE 5-1
RECOMMENDED CRITERIA FOR SELECTION OF GEOTEXTILES FOR EROSION
CONTROL APPLICATIONS
~.Hydraulic Requirements
A. Gap-graded soils, soils having C > 20, stratified soils, soils
subjected to changing flow direction, or wave wash.
(1) Piping Resistance
EOS (in mm) ^ Dft of soil to be protected
For soil having a D_ finer than the No. 70 sieve,
0.149 mm (No. 100 sieve) f EOS (in mm) ^ 0.210 (No. 70 sieve)
(2) Permeability/Clogging Resistance Requirement.
Woven fabrics: percent open area ^ 10
Nonwoven fabric: Gradient ratio < 3
B. All soils not covered by A, above.
(1) Piping Resistance
EOS (in mm) ^_ Dfi of soil to be protected
For soil having a D finer than the No. 70 sieve,
0.149 mm (No. 100 sieve) ^ EOS (in mm) < 0.210 (No. 70 sieve)
(2) Permeability/Clogging Resistance
k fabric ^ 10k soil
Alternate requirement (applicable to woven fabric only):
Percent open area > 4
(continued)
5-6
-------
TABLE 5-1 (continued)
II. Physical Requirements
Service Category A. Applications where rip-rap or other armor units are
dropped directly on the fabric from heights no greater than 0.9 m (3 ft), and
provided the underlying soil is sand or finer. If the underlying soil is
gravelly, the armor units should not be dropped onto the fabric unless field
tests are performed at the site to ascertain a maximum drop height that will
preclude damage to the geotextile.
Property
Tensile strength
Failure
elongation
Tear resistance
Puncture
resistance
Flexibility and
soil-fabric
friction
Test
Minimum Value
890 N (200 Ib)
in both principal
directions
20 percent in both
principal
directions
ASTM D 1682 grab test
using CRE testing machine
operated at 305 mm
(12 in.) per minute;
25 mm (1 in.) x 50 mm
(2 in.) jaws.
ASTM D 1682 grab test
using CRE testing machine
operated at 305 mm
(12 in.) per minute;
25 mm (1 in.) x 50 mm
(2 in.) j aws.
ASTM D 1117
Trapezoidal Tear
ASTM D 3787, modified by
replacing the steel ball
with an 8-mm-(5/16-in.-)
diameter steel rod having
a hemispherical tip.
No quantitative requirement. Fabric flexibility
and friction should be considered with respect
to ease of handling and ability to be placed on
slope without sliding. Use ASTM D 1388 to
evaluate flexibility.
311 N (70 Ib) in
both principal
directions
534 N (120 Ib)
(continued)
5-7
-------
TABLE 5-1 (continued)
II. Physical Requirements (continued)
Service Category B. Applications where a bedding layer is placed between
the fabric and the rip-rap or other armor units and the armor units are drop-
ped onto the bedding layer from heights no greater than 0.9 m (3 ft). The
underlying soil shall be sand or finer. If the underlying soil is gravelly,
the armor units shall not be dropped onto the fabric unless field tests are
performed at the site to ascertain the maximum drop height that will preclude
damage to the geotextile.
Property
Test
Tensile strength
Failure
elongation
Tear resistance
Puncture
resistance
Flexibility and
soil-fabric
friction
ASTM D 1682 grab test
using CRE testing machine
operated at 305 mm
(12 in.) per minute;
25 mm x 50 mm jaws.
ASTM D 1682 grab test
using CRE testing machine
operated at 305 mm
(12 in.) per minute;
25 mm x 50 mm jaws.
ASTM D 1117
Trapezoidal Tear
ASTM D 3787, modified by
replacing the steel ball
with an 8-mm-(5/16-in.-)
diameter steel rod having
a hemispherical tip.
No quantitative requirement. Fabric flexibility
and friction should be considered with respect
to ease of handling and ability to be placed on
slope without sliding. Use ASTM D 1388 to
evaluate flexibility.
Minimum Value
445 N (100 Ib) in
both principal
directions
20 percent in both
principal
directions
222 N (50 Ib) in
both principal
directions
178 N (40 Ib)
minimum
III. Environmental Resistance Requirements
A. Fibers used in the manufacture of the engineering fabric shall con-
sist of a long chain synthetic polymer consisting of at least
85 percent by weight propylene, ester, or vinylidene chloride. If
any material other than those specified above are proposed, they
must meet the requirements set forth in Table 3-2.
(continued)
5-8
-------
TABLE 5-1 (continued)
III. Environmental Resistance Requirements (continued)
B. The engineering fabric shall have a composition that may include
stabilizers; and shall be resistant to ultraviolet light and
weathering such that it shall retain at least 90 percent of its
initial tensile strength after 100-hr exposure in a Xenon
Weatherometer as specified in ASTM D 4355.
and other measures must be considered. Usually a combination of steepness of
slope and poor soil and/or moisture conditions leads to inadequate vegetative
protective cover and subsequent surface erosion and gulleying. Surface water
runoff and runoff from intermediate drainage layers within a landfill cover
must also be provided for. Where water velocities and flow volumes are high
and soil is erodible, it may be necessary to provide extra erosion protection.
Soils shown in Figure 5-1 to be erosion-susceptible are those for which some
protection in addition to vegetative cover is needed. An alternative cover
protective system is a geotextile placed over the cover soil and in turn
covered by gravel, cobbles, or rock fragments to hold the fabric in place and
protect it from extended exposure to ultraviolet radiation.
5.3.2 Landfill Cover Slopes
The fabric selection criteria for these applications are discussed in
Section 5.2 and summarized in Table 5-1. The construction procedure for
placement of fabric on landfill cover slopes consists of filling holes and
depressions in the slope so that the fabric is not required to bridge depres-
sions and be torn from lack of support when the cover materials are installed.
Large stones, limbs, stumps, and other debris should also be removed before
placing the fabric to reduce the chances of puncturing. The fabric should
then be placed directly on the slope with the machine direction of the fabric
lying up and down the slope. Adjacent fabric panels and ends of rolls should
be overlapped at least 0.3 m (12 in.) with the upslope ends overlapping the
downslope ends, as shown in Figure 5-3. Since overlapping can use consider-
able fabric, seams should be sewn whenever possible either in the factory or
by portable sewing machines at the site. Sewing should be performed using
polyester, polypropylene} or nylon threads and the seam strength for both
factory and field seams should equal at least 90 percent of fabric strength as
tested using ASTM D 1683. Fabric may be held on the slope with steel pins
before placing the cover stone, or it may be simply weighed with sandbags or
rocks. Steel pins 4.8 mm (3/16 in.) in diameter by 0.46 m (18 in.) long with
38-mm- (1.5-in.-) diameter heads have proved satisfactory for anchoring fabric
in relatively firm soil. Longer pins may be needed in loose soil. On steep
slopes, it may be difficult to prevent slippage of the fabric on the slope and
slippage of the cover material on the fabric. In instances where steep slopes
are to be covered and the fabric is relatively stiff or the fabric finish is
relatively slick, it is advisable to perform trials before fabric selection to
5-9
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FIGURE 5-3
METHOD OF PLACING FABRIC FOR PROTECTION OF CUT AND FILL SLOPES
(Haliburton et al., 1981)
Ulrica i njii
OF SLOPE
/
5 FT. MINIMUM-7
OFFSET BETWEEN
ADJACENT ROLL
ENDS
-1
~r
__.
t
1
— T
i
— i
i
1
r
-1
12 IN. MINIMUM
FABRIC OVERLAP
MACHINE DIRECTION
OF FABRIC
-CROSS DIRECTION
OF FABRIC
determine whether the fabric will be able to be placed on the slope without
sliding. Use the minimum amount of fabric anchoring necessary to keep the
fabric in place before placement of the cover material. The cover stone
should then be placed from the bottom of the slope upward. Experience has
shown that fabric should not be pinned on slopes steeper than IV on 3H, as the
fabric will slide down the slope to some degree as the cover material is
placed so that extra fabric must be allowed at the top of the slope (Couch,
1982).
Exposure of the fabric to sunlight during installation should be mini-
mized and maximum total exposure should not exceed 30 days.
5.3.3 Drainage Channels and Culvert Outlets
If slopes are shallow enough, if the nature of the soil is nonerosive,
and if the water volumes to be conveyed are small, vegetative cover is all
that is needed to provide permanent erosion protection for drainage channels.
These cases can use specialized fabrics designed to prevent erosion while
grass or other protective vegetation is established. Such fabrics are de-
signed to degrade after the vegetation has had time to establish itself. At
least one matlike product is available that provides erosion protection while
seedlings are being established, and is designed to resist environmental
deterioration and serve as additional root anchoring after plant cover has
established itself.
In cases where it is not desirable or feasible to establish vegetative
cover for erosion protection, a layer of cobbles or rock fragments can be used
to line the ditch. To prevent the rock from sinking into the soil and having
the flowing water erode soil from between the rocks, a layer of fabric can be
placed between the rock and soil. Selection criteria for the fabric are dis-
cussed in Section 5.2 and summarized in Table 5-1. Before installation of the
5-10
-------
fabric, the area to be covered should be smoothed, and any depressions should
be filled and soft spots compacted. Large rocks, limbs, roots, and other
debris should be removed before placing the fabric to prevent punctures.
Fabric should be unrolled with the machine direction parallel to the alignment
of the ditch. Most fabrics are wide enough that the entire width of the ditch
can be covered by the width of one roll of fabric. In cases where the width
of the ditch is wider than one roll, the edges of the adjacent rolls should be
sewn rather than overlapped. The reason is that in most cases where two rolls
are required to cover the width of a ditch or channel, the seam will fall in
the center of the channel (see Figure 5-4) where erosion and undermining
potential is greatest. The ends of rolls should be overlapped at least 0.9 m
(3 ft), with the upstream roll overlapping the downstream roll to provide a
shingling effect and retard undermining (Figure 5-5) .
In cases where culverts or pipe outlets empty into drainage ditches,
fabric covered with stone or concrete blocks provides scour protection against
the concentrated flows at these locations. Figure 5-6 shows fabric placement
for this type of application.
5.4 Streambank and Wave Protection
5.4.1 Fabric Requirements
Though placing a solid waste disposal facility adjacent to a stream,
lake, or shoreline would be rejected today as unsuitable because of potential
ground-water and erosion problems, many existing waste dumps are located adja-
cent to streams or along shore areas. Consequently, remedial action plans may
require erosion protection along streambanks and shorelines. Streambank and
shoreline erosion results from scouring by tractive forces of water against
erodible soils and from seepage out of the Streambank or shoreline slope.
Seepage out of a bank or slope can result from water flow into the bank when
stream levels are high, followed by flow out of the bank when water levels
recede, or it can result from wave wash causing water flow into the bank dur-
ing wave crests, followed by seepage out of the bank as the wave recedes.
This reversing flow condition is a severe test for a geotextile's resistance
to clogging. Selection of fabric with good clogging resistance is extremely
important to prevent slope failure as a result of high pore pressures from
flow restriction through the fabric and out of the bank. The fabric selection
criteria 'for Streambank protection applications are discussed in Section 5.2
and summarized in Table 5-1.
5.4.2 Streambank Protection Construction Procedures
The procedures given here are essentially those proposed by Keown and
Dardeau (1980). The bank should be cleared of vegetation and graded to a
smooth slope. Pockets of soft soil should be excavated and replaced or com-
pacted. Rock or other debris that may cause puncturing of the fabric should
be removed. The fabric should be unrolled onto the bank, with the roll length
parallel to the direction of stream flow. Adjacent fabric panels should have
a minimum overlap of at least 0.3 m (12 in.) along edges and at the ends of
rolls. When the fabrics overlap, the upstream edge should have a minimum
1.5 m (5 ft) offset between roll ends of adjacent panels. Edges of upslope
5-11
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FIGURE 5-4
PLACEMENT OF FABRIC IN SWALE AT WINDHAM, CONNECTICUT, LANDFILL (Lutton, et al., 1982)
Ul
I
-------
FIGURE 5-5
USE OF FABRIC IN CONSTRUCTION OF RUNOFF COLLECTION/DIVERSION DITCHES
(Haliburton, et al., 1981)
••.•',
•M
Pfc \
CENTERLINE PROFILE OF FABRIC LINED-DITCH
FIGURE 5-6
USE OF FABRIC TO PROVIDE SCOUR PROTECTION FOR CULVERT OUTLET
(Haliburton et al., 1981)
CULVERT/DRAIN PIPE
RIPRAP, CONCRETE BLOCKS,
COVER STONE, ETC
SECURING PIN
ENGINEERING FABRIC
5-13
-------
panels should be placed over downslope edges. The preferred arrangement of
fabric panels is shown in Figure 5-7. Sewing adjacent panels is preferred to
lapping to reduce fabric waste and produce a more secure connection between
panels. Fabric may be held in place on the bank before placement of cover
material by means of securing pins as described in Section 5.3.2.
Fabric should be placed along the bank to an elevation below mean low
water determined by criteria developed for other slope protection; otherwise,
place fabric and cover material to a vertical distance at least 0.9 m (3 ft)
below mean low water. The top of the fabric and cover material should extend
to the top of the bank or to an elevation adopted for other forms of slope
protection. If no other guidelines are available, fabric should be placed to
an elevation 0.6 m (2 ft) above expected maximum water stage. If overtopping
of the streambank is expected, or if significant overbank runoff is expected,
the top edge of the fabric should be buried or otherwise keyed into the slope
to prevent undermining. This should be done after placement of cover stone to
prevent excessive tension in the fabric during placement. See Figure 5-8 for
methods of anchoring fabric at the top of the slope. If a bedding layer is
used between the armoring and fabric, the bedding must be more permeable than
the underlying soil, and it must be of such a gradation as to be held in place
by the armoring material. Stone should be placed from the bottom of the slope
upward, rather than being dumped from the top of the slope.
5.4.3 Wave Protection
The techniques for using fabric to protect against wave action are very
similar to those used for streambank protection. Just as with streambank
protection, clogging of the fabric under reversing flow conditions is the
greatest potential cause of poor performance. The fabric selection procedures
for this application are discussed in Sections 5.1 and 5.2 and summarized in
Table 5.1. In keeping with the practice of placing the long (machine)
direction of the fabric in the direction of primary water movement, the fabric
panels should be laid out up and down the slope. If fabric must be placed
under water, 0.9 m (3 ft) overlaps at the fabric edges should be used wherever
the fabric cannot be sewn before placement. If possible, fabric panels should
be presewn at the factory and pulled downslope into the water. Fabric should
be keyed in at both the top and bottom of the slope. Recommended treatments
for top and toe of slope are illustrated in Figure 5-8. Though riprap is the
most common armoring material, prefabricated blocks of various designs can be
used. If prefabricated blocks are of such a design that a substantial area of
the fabric is covered by the blocks, a bedding layer is recommended to
facilitate drainage from the underlying soil through the openings in the
blocks.
5-14
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FIGURE 5-7
CROSS SECTIONS AND FABRIC PLACEMENT DETAIL FOR USE OF FABRIC
IN STREAMBANK PROTECTION (Keown and Dardeau, 1980)
LAP UPSLOPE EDGE
OVER DOWNSLOPE EDGE
DESIGN
FLOOD STAGE
PLACE COVER
STONE UPSLOPE
SECURING
PIN
3 FT.
MIN.
MEAN
LOW WATER
L STREAMBANKn
CROSS-SECTION OF STREAMBANK REVETMENT
TOP OF BANK
^
A
1 FT. MINIMUM
OVERLAP___
DIRECTION --- ---- - — —
OF __ . __ _.
CURRENT - -
FABRIC MACHINE
DIRECTION
h-5 FT. MINIMUM
OFFSET
FABRIC PLACEMENT SCHEME FOR
STREAMBANK PROTECTION
5-15
-------
FIGURE 5-8
EXAMPLE ANCHORING TREATMENTS AT TOP AND TOE OF FABRIC IN WAVE PROTECTION
STRUCTURES (Bell and Hicks, 1983)
Geotextile
Top Treatments
Geotextile
Geotextile
Toe Treatments
5-16
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6.0 REFERENCES
Allen, T., Vinson, T. S., and Bell, J. R. 1982. "Tensile Strength and Creep
Behavior of Geotextiles in Cold Regions Applications," Proceedings, Second
International Conference on Geotextiles, Las Vegas, Vol 3, pp 775-780.
Amoco Chemicals Corporation. 1980. "Chemical Resistance of Polypropylene,"
Polymers Technical Service Bulletin PP-Properties-001, Polymers Technical
Service, Naperville, 111.
Anderson, D., and Brown, K. W. 1981. "Organic Leachate Effects on the
Permeability of Clay Liners," Proceedings, Seventh Annual Research Symposium,
EPA-600/9-81-026, US Environmental Protection Agency, Municipal Environmental
Research Laboratory, Ft. Mitchell, Ky., pp 119-130.
Baldwin, R. D. 1983. "Lining a Pond to Contain Uranium Tailings," Civil
Engineering. Vol 53, No. 1, pp 77-79.
Bell, J. R., and Hicks, R. G. 1983. "Evaluation of Test Methods and Use
Criteria for Geotechnical Fabrics in Highway Applications, Final Report,"
Federal Highway Administration, Washington, B.C.
Bell, J. R., Hicks, R. G., et al. 1980. "Evaluation of Test Methods and Use
Criteria for Geotechnical Fabrics in Highway Applications, Interim Report,"
FHWA/RD-80/021, Federal Highway Administration, Washington, D.C.
Blair, J. C., Bell, J. R., and Hicks, R. G. 1981. "Permeability Testing of
Geotextiles," Transportation Research Record No. 826, National Academy of
Sciences, Washington, B.C., pp 1-6.
British Standards Institute, 1963, Methods of Tests for Textiles, B.5.3321,
Handbook No. 11, London.
Burke Rubber Company n.d. "Hypalon Liner Design Details," Burke Technical
Literature Package on Flexible Membranes, San Jose, Calif.
Calhoun, C. C. 1972. "Development of Design Criteria and Acceptance
Specification for Plastic Filter Clothes," Technical Report S-72-7, U. S. Army
Engineer Waterways Experiment Station, Vicksburg, Miss.
Cedergren, H. R, 1977a, "Permeability," Seepage, Drainage, and Flow Nets,
Second Edition, Chapter 2, John Wiley, New York.
Cedergren, H. R., 1977b," Filter and Drain Design," Seepage, Drainage, and
Flow Nets, Second Edition, Chapter 5, John Wiley, New York.
6-1
-------
Chen, Yung Hal, Simmons, Daryl B., and Demery, Phillip M. 1981. "Hydraulic
Testing of Plastic Filter Fabrics," Journal of the Irrigation and Drainage
Division, American Society of Civil Engineers, Vol 107, No. IR3, pp 307-324.
Christopher, B. 1983a. "Geotextiles," Standardization News, Vol 11, No. 10,
pp 25-28.
Christopher, B. R. 1983b. "Evaluation of Two Geotextile Installations in
Excess of a Decade Old," Transportation Research Record 916, National Academy
of Sciences, Washington, D.C., pp 79-88.
Couch, F. B., Jr. 1982. "Geotextile Applications to Slope Protection for the
Tennessee-Tombigbee Waterway Divide Cut," Proceedings, Second International
Conference on Geotextiles, Vol 1, p 217-222.
Department of the Army. 1970. "Hydraulic Design of Flood Control Channels,"
Engineer Manual EM 1110-2-1601, Office of the Chief of Engineers, Washington,
D.C.
Department of the Army. 1971. "Engineering and Design: Earth and Rock-fill
Dams General Design and Construction Considerations," Engineer Manual
EM 1110-2-2300, Office of the Chief of Engineers, Washington, D.C.
Department of the Army. 1977. "Plastic Filter Fabric," Civil Works Construc-
tion Guide Specification CW-02215, Office of the Chief of Engineers,
Washington, D.C.
Department of the Army. 1978. "Engineering and Design: Design Construction
of Levees," Engineer Manual EM 1110-2-1913, Office of the Chief of Engineers,
Washington, D.C.
Du Pont Company. 1976. "Characteristics and Uses of Kevlar 29 Aramid,"
Preliminary Information Memo No. 375, Textile Fibers Department, Wilmington,
Del.
Gibbs, H. J., and Holtz, W. G. 1962. "A Study of Erosion and Tractive Force
Characteristics in Relation to Soil Mechanics Properties - Earth Research
Program," Soils Engineering Report EM-643, U. S. Department of the Interior
Bureau of Reclamation, Denver, Colo.
Giroud, J. P. 1981. "Designing with Geotextiles," Materials and Structures,
The International Union of Testing and Research Laboratories for Materials and
Structures, Vol 14, No. 82, July-August 1981, pp 257-272.
Giroud, J. P. 1982. "Design of Geotextiles Associated with Geomembranes,"
Proceedings, Second International Conference on the Use of Fabrics in Geotech-
nics, Las Vegas, pp 37-42.
Giroud, J. P. and Bonaparte, R. 1984. "Waterproofing and Drainage:
Geomembrane and Synthetic Drainage Layers," Symposium on Plastic and Rubber in
Waterproofing, Liege, Belgium.
6-2
-------
Haliburton, T. A., Anglin, C. C., and Lawmaster, J. D. 1978. "Selection of
Geotechnical Fabrics for Embankment Reinforcement," Report to U. S. Army
Engineer District, Mobile, by School of Civil Engineering, Oklahoma State Uni-
versity, Stillwater, Okla.
Haliburton, T. A., Lawmaster, J. D., and McGuffey, V. C. 1981. "Use of
Engineering Fabrics in Transportation-Related Applications," Prepared for
Federal Highway Administration by Haliburton Associates, Stillwater, Okla.
Haliburton, T. A., Petry, T. M., and Hayden, M. L. 1975. "Identification and
Treatment of Dispersive Clay Soils," Research Report to U. S. Department of
the Interior, Bureau of Reclamation, School of Civil Engineering, Oklahoma
State University, Stillwater, Okla.
Haliburton, T. A., and Wood, P. D. 1982. "Evaluation of the U. S. Army Corps
of Engineers Gradient Ratio Test for Geotextile Performance," Proceedings,
Second International Conference on Geotextiles, Las Vegas, pp 97-101.
Hansbo, S. 1981. "Consolidation of Fine Grained Soils by Prefabricated
Drains," Proceedings of the Tenth International Conference on Soil Mechanics
and Foundation Engineering, Stockholm, Vol 3, pp 677-682.
Hoare, D. J. 1982. "Synthetic Fabrics as Soil Filters: A Review," Journal
of the Geotechnical Engineering Division, American Society of Civil Engineers,
Vol 108, No. GT10, pp 1230-1245.
Hoerchst Fibers Industries. 1979. "Resistance of Trevira High Tenacity,"
Technical Information Bulletin F0002, American Hoerchst Corporation
Spartanburg, S.C.
Hunt, J. A.. 1982. "The Development of Fin Drains for Structure Drainage,"
Proceedings, Second International Conference on Geotextiles, Las Vegas, Vol 1,
pp 25-30.
Kays, W. B. 1977. "Failure Mechanisms," Construction of Linings for Reser-
voirs, Tanks, and Pollution Control Facilities, Chapter 7, John Wiley, New
York. pp 198-199.
Keown, M. P., and Dardeau, E. A., Jr. 1980. "Utilization of Filter Fabric
for Streambank Protection Applications," Technical Report HL-80-12, U. S. Army
Engineer Waterways Experiment Station, Vicksburg, Miss.
Kjellmann, W. 1948. "Accelerating Consolidation of Fine Grained Soils by
Means of Card Wicks," Proceedings, Second International Conference on Soil
Mechanics and Foundation Engineering, Rotterdam, Vol 2, pp 302-305.
Koerner, R. M., and Bove, J. A. 1983. "In-Plane Hydraulic Properties of
Geotextiles," Geotechnical Testing Journal, Vol 6, No. 4, pp 190-195.
Koerner, R. M., and Sankey, J. E. 1982. "Transmissivity of Geotextiles and
Geotextile/Soil Systems," Proceedings, Second International Conferences on
Geotextiles, Vol 1, pp 173-176.
6-3
-------
Lawson, C. R. 1982. "Filter Criteria for Geotextiles: Relevance and Use,"
Journal of the Geotechnical Engineering Division, American Society of Civil
Engineers, Vol 108, No. GT10, pp 1300-1317.
Lee, P. E. 1977. "Use of Bidim-C34 Filter Fabric in Shoreline Erosion
Protection Wright Patman Dam and Lake Atlanta State Recreation Area Bowie and
Cass Counties, Texas," Report prepared (in cooperation with the New Orleans
District, U. S. Army Corps of Engineers) for Monsanto Textiles.
LeFlaive, E., Paute, J. L., and Segouin, M. 1982. "Strength Properties
Measurement for Practical Applications," Proceedings, Second International
Conferences on Geotextiles," Las Vegas, pp 733-738.
Lutton, R. J., Torrey, V. H. Ill, and Fowler, J. 1982. "Case Study of
Repairing Eroded Landfill Cover," Proceedings, Eight Annual Research
Symposium, EPA-600/9-82-002, U. S. Environmental Protection Agency, Municipal
Environmental Research Laboratory, Ft. Mitchell, Ky., pp 486-494.
Mallard, P., and Bell, J. R. 1981. "Use of Fabrics in Erosion Control,"
Transportation Research Report 81-4, Oregon State University, Corvallis, Oreg.
Masounave, J., Denis, R., and Rollin, A. L. 1980. "Prediction of Hydraulic
Properties of Synthetic Nonwoven Fabrics Used in Geotechnical Work," Canadian
Geotechnical Journal, Vol 17, No. 4, pp 517-525.
McGown, A., and Andrawes, K. Z. 1982. "An Approach to Laboratory Testing of
Geotextiles," Quarterly Journal of Engineering Geology, Vol 15, No. 3,
pp 177-185.
McGown, A., Andrawes, K. Z., and Kabir, M. H. 1982. "Load-Extension Testing
of Geotextiles Confined In-Soil," Proceedings, Second International Conference
on Geotextiles, Las Vegas, Vol 3, pp 793-798.
McGown, A., and Hughes, F. H. 1981. "Practical Aspects of the Design and
Installation of Deep Vertical Drains," Geotechnique, Vol 31, No. 1, pp 3-17.
Ogink, H. J. M. 1975. "Investigation on the Hydraulic Characteristics of
Synthetic Fabrics," Delft Hydraulics Laboratory Publication No. 146, Delft,
Holland.
Phillips Fibers Corporation, n. d. "Availability and Properties of Marvess
Olefin, Chemical Properties," Bulletin M-2, Rev., Greenville, S.C.
Raumann, G. 1982. "inplane Permeability of Compressed Geotextiles,"
Proceedings, Second International Conference on Geotextiles, Vol 1, pp 55-60.
Risseeuw, P., and van den Elzen, L. W. A. 1977. "Construction on Compres-
sible Saturated Subsoils with the Use of Non-woven Strips," Proceedings
International Conference on the Use of Fabrics in Geotechnics, Paris,
pp 265-271.
6-4
-------
Ruddock, E. C. 1977. "Tests on Woven and Non-woven Fabrics for Pore Size and
Damage by Aggregate," Proceedings, International Conference on the Use of
Fabrics in Geotechnics. Paris, Vol 2, pp 317-322.
Rycroft, D. and Dennis Jones, P. 1982. "Geotextile Filtration Performance
and Current Filter Criteria," Proceedings, Second International Conference on
Geotextiles, Vol 1, pp 67-72.
Schober, W. and Teindl, H. 1979. "Filter Criteria for Geotextiles," Seventh
European Conference on Soil Mechanics and Foundation Engineering, Vol 2,
pp 121-129.
Sherard, J. L. 1979. "Sinkholes in Dams of Coarse, Broadly Graded Soils,"
Thirteenth Conference of the International Congress on Large Dams, New Delhi,
Vol 2, pp 25-35.
Sherard, J. L., Duningham, Larn P., and Talbot, James R. 1984a. "Basic
Properties of Sand and Gravel Filters," Journal of Geotechnical Engineering,
Vol 110, No. 6, pp 684-700.
Sherard, J. L., Duningham, Larn P., and Talbot, James R. 1984b. "Filters for
Silts and Clays," Journal of Geotechnical Engineering, Vol 110, No. 6,
pp 701-718.
Shrestha, S. C., and Bell, J. R. 1982a. "A Wide Strip Tensile Test of
Geotextiles," Proceedings, Second International Conference on Geotextiles, Las
Vegas, Vol 3, pp 739-744.
Shrestha, S. C., and Bell, J. R. 1982b. "Creep Behavior of Geotextiles Under
Sustained Loads," Proceedings, Second International Conference on Geotextiles,
Las Vegas, Vol 3, pp 769-774.
Sissons, C. R. 1977. "Strength Testing in Fabrics for Use in Civil Engineer-
ing," Proceedings, International Conference on the Use of Fabrics in Geo-
technics, Paris, Vol 2, pp 287-292.
Steward, J. E., Williamson, R., and Mohney, J. 1977. "Guidelines for Use of
Fabrics in Construction of Low Volume Roads," Report No. FHWA-TS-78-205,
Federal Highway Administration, Washington, D.C.
Terzaghi, K. 1922. "Der Grundbruch an Stauwerken und seine Verhutung" (The
failure of dams by piping and its prevention), Die Wasserkaft, Vol 17,
pp 445-449. Reprinted in From Theory to Practice in Soil Mechanics, by
A. Casagrande, John Wiley, New York, 1960, pp 114-118.
Thacker, Barry K. and Schad, J. A. 1983. "Rapid Construction of a Combined
Coal Refuse Embankment," Proceedings, Fourteenth Ohio River Valley Soils
Seminar, Louisville, Ky.
6-5
-------
Thanikachalam, V., Sakthivadivel, R., and Kulandaiswamy, V. C. 1972. "A
Critical Reappraisal of the Design Criteria for Filters," Council of Scienti-
fic and Industrial Research Project, Report 7, Hydraulics and Water Resources
Department, College of Engineering, Madras 25, India.
U. S. Environmental Protection Agency. 1982. "Handbook for Remedial Action
at Waste Disposal Sites," EPA-625/6-82-006, Municipal Environmental Research
Laboratory, Cincinnati, Ohio.
Viergever, M. A., Defyter, J. W4, and Mour, K. A. G. 1977. "Biaxial Tensile
Strength and Resistance to Cone Penetration of Membrane," Proceedings, Inter-
national Conference on the Use of Fabrics in Geotechnics, Paris, Vol 2,
pp 311-316.
Williams, N., Giroud, J. P., and Bonaparte, R. 1984. "Properties of Plastic
Nets for Liquid and Gas Drainage Associated with Geomembranes," Proceedings,
International Conference on Geomembranes, Denver, pp 399-404.
Wolf, T., and Christopher, B. 1982. "Utilization of Geotextiles in Waste
Management," Proceedings, Second International Conference on Geotextiles, Las
Vegas, Vol 3, pp 641-646.
6-6
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7.0 BIBLIOGRAPHY
Christopher, B. R. , and Holtz, R. D. 1984. "Geotextile Engineering Manual,"
course text prepared for Federal Highway Administration, Washington, D.C.
Koerner, R. M., and Welsh, J. P. 1980. Construction and Geotechnical
Engineering Using Synthetic Fabrics, John Wiley and Sons, New York.
Proceedings, International Conference on the Use of Fabrics in Geotechnics.
1977. Ecole Nationale des Fonts et Chaussees, Paris, 3 Volumes.
Proceedings, Second International Conference on Geotextiles, 1982. Industrial
Fabrics Association International, St. Paul, Minn., 4 Volumes.
Rankilor, P. R. 1981. Membranes in Ground Engineering, John Wiley and Sons,
Chichester, U.K.
U.S. Department of Transportation. 1978. "Sample Specifications for
Engineering Fabrics," FHWA Report TS-78-211, Federal Highway Administration,
Washington, D.C.
7-1
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APPENDIX A
ACTIVE MARKETERS OF FABRICS, STRIP DRAINS, AND
DRAINAGE PANELS
DISTRIBUTORS OF GEOTEXTILES
U. S. Distributors
Advance Construction Specialties Co,
PO Box 807
Dresden, TN 38225
ATTN: Mr. H. M. Vann
Tel: (901) 364-5417
American Enka Company
Enka, NC 28728
ATTN: Mr. Carl Warren
Tel: (704) 667-7110
AMOCO Fabrics Co.
Patchogue-Plymouth Division
Civil Engineering Department
550 Interstate North, Suite 150
Atlanta, GA 30099
Tel: (404) 955-0935
Bradley Materials Company, Inc.
PO Box 254
Valparaiso, FL 32580
Tel: (904) 678-1105
Burlington Industrial Fabrics Co.
261 Madison Ave.
New York, NY 10016
ATTN: Pete Stevenson
(212) 953-1100
Carthage Mills Erosion Control Co.
124 W. 66th Street
Cincinnati, OH 45216
Tel: (513) 242-2740
Crown Zellerbach Corp.
Nonwoven Fabrics Division
PO Box 1115
Camas, WA 98607
ATTN: Tom Collins
Product Manager
Construction Fabrics
Tel: (206) 834-5954
(800) 426-0700
E. I. Du Pont de Nemours & Co., Inc.
Textile Fibers Department
Centre Road Building
Wilmington, DE 19898
ATTN: Technical Service & Marketing
Tel: (302) 774-9798
(800) 441-9475
Erosion Control Systems
Div. of Gulf States Paper Corp.
PO Box 3199
Tuscaloosa, AL 35404
Tel: (205) 553-6200
Erosion Control, Inc.
117 Canaveral Beach Blvd.
Cape Canaveral, FL
ATTN: Mr. Sivard
Tel: (305) 783-6250
A-l
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Foss Manufacturing Co., Inc.
1 Whitney Avenue
PO Box 175
Haverhill, MA 01830
ATTN: Brian Jeffrey
Tel: (617) 374-0121
Griffolyn Company
Division of Reef Industries
PO Box 33248
Houston, TX 77033
Tel: (713) 943-0070
(800) 231-6074
Hoechst Fibers Industries
Division of American Hoechst Corp.
PO Box 5887
Spartanburg, SC 29304
Tel: (800) 845-7597
ICI Americas
Resale Department
Wilmington, DE 19897
ATTN: R. A. Fenimore
Tel: (302) 575-3066
Mercantile Development, Inc.
274 Riverside Avenue
Westport, CT 06880
Tel: (203) 226-7803
Mirafi, Inc.
PO Box 240967
Charlotte, NC 28224
Tel: (704) 588-4550
(800) 438-1855
Nicolon Corp.
Suite 1990, Peachtree Corners Plaza
Norcross/Atlanta, GA 30071
Tel: (404) 447-6272
(800) 241-9691
Owens-Corning Fiberglas Corp.
Technical Center
PO Box 415
Granville, OH 43023
ATTN: John Mancaster
Tel: (614) 587-0610
Phillips Fibers Corp.
PO Box 66
Greenville, SC 29602
ATTN: Engineered Products Marketing
Tel: (803) 242-6600
(800) 845-5737
Quline Corp.
560 S. Spring Court
Raleigh, NC 27658
Tel: (919) 872-7299
Staff Industries
78 Dryden Road
PO Box 759
Upper Montclair, NJ 07043
ATTN: C. E. Staff
Tel: (201) 744-5367
The TENSAR Corporation
1210 Citizens Parkway
Morrow, GA 30260
Tel: (404) 968-3255
Terrafix Erosion Control Products, Inc,
9151 Fairgrounds Road
West Palm Beach, FL 33411
Tel: (305) 793-5650
(305) 793-5727
Wayne-Tex, Inc.
901 S. Delphine Avenue
Waynesboro, VA 22980
ATTN: Frank Perkins
Tel: (703) 943-2500
West Point Pepperell, Inc.
Industrial Fabrics Division
Research Center
PO Box 398
Chawmut, AL 36876
ATTN: Bruce Helzschuh
Tel: (205) 756-7111, ext 2429
A-2
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Non-U. S. Distributors
Bay Mills Midland, Limited
305 Evans Avenue
Toronto, Ontario
ATTN: Graham Tyler
Tel: (416) 252-5711
Dominion Textile, Ltd.
1950 Sherbrook St.
Montreal, Quebec
ATTN: P. Moldvar, Marketing Manager
Tel: (514) 937-5711
Enka bv
Industrial Systems-Geotechnics
Velperweg 76
Postbus 306
6800 AH Arnhem-Holland
Tel: 085-664600
Telex 45204
Low Brothers & Co. (Dundee) Ltd.
Box 54 Southward Rd.
Dundee Scotland DD19JO
ATTN: R. G. Warwick
Tel: 0382-27311
Neton Ltd.
Mill Hill, Blackburn BB2 4PJ
Great Britain
Tel: Blackburn (0254) 62431
U. S. MARKETERS OF STRIP DRAINS
Alidrain
Vibroflotation Foundation Company
United States Steel Building,
39th Floor
600 Grant Street
Pittsburgh, PA 15219
Telephone: (412) 288-7676
Contact: James Warren
Amerdrain
International Construction
Equipment, Inc.
301 Warehouse Drive
Mathews, NC 28105
Telephone: (704) 821-7681
Castle Drain Boards
Harquim International Corporation
3112 Los Feliz Boulevard
Los Angeles, CA 90039
Telephone: (213) 669-8332
Geodrain
Griffin International Drainage Corp,
100 South Broadway
Irvington, NY 15033
Telephone: (914) 591-6000
Contact: Robert Anderson
Mebra Drain
Geotechnics America, Ind.
6830 Hilo Street
Diamondhead
Bay St. Louis, MS 39520
Telephone: (601) 255-3123
Contact: Russell Joiner
A-3
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U. S. MARKETERS OF PREFABRICATED DRAINAGE SYSTEMS
Eljen Drainage System
Eljen Development Corp.
15 Westwood Rd.
Storrs, CT 06268
Telephone: (203) 429-9986
Enkadrain
American Enka Co.
Enka, NC 28728
Telephone: (704) 667-7713
Hitek Prefabricated Drains
Vibroflotation Foundation Co.
United States Steel Bldg.
600 Grant St.
Pittsburgh, PA 15219
Telephone: (800) 245-1762
(412) 288-7676
Medradrain
Mirafi Inc.
PO Box 240967
Charlotte, NC 28224
Telephone: (800) 438-1855
(704) 588-4550
A-4
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APPENDIX B
TEST METHODS AND STANDARDS
B.I Introduction
This appendix lists those published test methods and standards reported
in the body of this handbook (see Table B-l). Many tests are currently being
developed specifically for geotextiles by ASTM Committee D 35 on Geotextiles
and Related Products. Those agencies or individuals wishing to cite standard-
ized test methods for geotextiles should contact the staff manager for Commit-
tee D 35, ASTM Headquarters, 1916 Race Street, Philadelphia, PA 19103 to
ascertain the status of the many standards under development by this
committee.
Detailed test procedures are given in this appendix for the fabric
permeability test and the percent open area test, for which there are at
present no published standards. Procedures are also given for the gradient
ratio test and equivalent opening size (EOS) test. While these tests are
described in the U. S. Army Corps of Engineers Guide Specification CW-02215,
the procedures given here are more complete and retain the essential features
described in the Guide Specification.
B.2 Suggested Test Method for Permeability and Permittivity of Geotextiles
B.2.1 Scope
This method covers a procedure for determining the hydraulic conductivity
(water permeability) of geotextiles in terms of permittivity under a standard
set of testing conditions.
B.2.2 Applicable Documents:
The following documents are applicable:
ASTM Standards
D 123 Definitions of Terms Relating to Textiles
Q
This test method has been reproduced from Christopher, B. R., and
Holtz, R. D., 1984, "Geotextile Engineering Manual," prepared for the Federal
Highway Administration under Contract No. DTFH61-80-C-00094, Washington, D.C.
This test method has been reproduced from Haliburton, T. A.,
Lawmaster, J. D., and McGuffey, V. C. 1981. "Use of Engineering Fabrics in
Transportation-Related Applications," prepared for the Federal Highway
Administration under Contract No. DTFH61-80-C-00094, Washington, D.C.
B-l
-------
TABLE B-l
PUBLISHED TEST METHODS AND STANDARDS
Number
D 123
C 666
D 543
D 572
D 746
D 1117
D 1388
D 1435
D 1682
D 1683
D 1777
D 2256
D 2262
D 2905
D 2990
D 3083
D 3786
Date of
Issuance
84
84
67
81
79
80
64
75
64
81
64
80
83
83
77
76
80a
Title
ASTM
Terminology Relating to Textiles
Resistance of Concrete to Rapid Freezing
and thawing
Resistance of Plastics to Chemical Reagents
Rubber Deterioration by Heat and Oxygen
Brittleness Temperature of Plastics and
Elastomers by Impact
Nonwoven Fabrics (Trapezoidal Tear Test)
Stiffness of Fabrics (Cantilever Test)
Outdoor Weathering of Plastics
Breaking Load and Elongation of Textile
Fabrics
Failure in Sewn Seams of Woven Fabrics
Thickness of Textile Materials
Breaking Load (Strength) and Elongation
of Yarn by the Single-Strand Method
Tearing Strength of Woven Fabrics by the
Tongue (Single Rip) Method (Constant Rate
of Traverse Tensile Testing Machine)
Number of Specimens Required to Determine
the Average Quality of Textiles
Tensile, Compressive, and Flexural Creep
and Creep Rupture of Plastics
Flexible Poly (Vinyl Chloride) Plastic
Sheeting for Pond, Canal, and Reservoir
Lining [Soil burial test]
Hydraulic Bursting Strength of Knitted
Goods and Nonwoven Fabrics: Diaphragm
Bursting Strength Tester Method
Reference
Part No.b
07.01,
07.02
04.02
08.01
09.01
08.01,
09.02
07.01
07.01
08.01
07.01
07.01
07.01
07.01
07.01
08.02
04.04
07.01
(continued)
'l984 Annual Book of ASTM Standards. Revision issued annually.
B-2
-------
TABLE B-l (continued)
Number
D 3787
D 3884
D 4354
D 4355
E 838
G21
G 22
G 23
G 26
G 29
CW-02215
CRD-C-575-60
Date of
Issuance
80a
80
84
84
81
70
76
81
83
75
77
60
Title
ASTM
Bursting Strength of Knitted Goods:
Constant-Rate-of Traverse (CRT), Ball Burst
Test [Modified0]
Abrasion Resistance of Textile Fabrics
(Rotary Platform, Double Head Method)
Sampling Geotextiles for Testing
Deterioration of Geotextile from Exposure
to Ultraviolet Light and Water (Xenon-Arc
Type Apparatus)
Performing Accelerated Outdoor Weathering
Using Concentrated Natural Sunlight
Resistance of Synthetic Polymeric Materials
to Fungi
Resistance of Plastics to Bacteria
Light and Water-Exposure Apparatus (Carbon-
Arc Type) for Exposure of Nonmetallic
Materials
Operating Light-Exposure Apparatus (Xenon-
Arc Type) With and Without Water for
Exposure of Nonmetallic Materials
Algal Resistance of Plastic Films
Department of the Army
Plastic Filter Fabric [EOS test and
Gradient Ratio Test]
Weight Change in Water
Reference
Part No.
07.01
07.01
04.08e
04.08e
12.02
08.03,
14.02
08.03,
14.02
07.01,
08.03,
14.02
08.03,
14.02
14.02
f
g
(continued)
Test procedure modified by replacing 25-mm- (1.0-in.-) diameter ball with an
8-mm- (0.31-in.-) diameter rod having a hemispherical tip.
Rubber-base abrasive wheels equal to CS-17 Calibrase by Taber Instrument Co;
1 kilogram load per wheel; 1000 revolutions; determine residual breaking
strength.
Currently available as a separate document only; to be published in 1985
Annual Book of ASTM Standards, Part 04.08.
Published by Headquarters, U. S. Army Corps of Engineers, Washington, D.C.
^Handbook for Concrete and Cement, Published by U. S. Army Corps of Engineers
in 1949 and revised periodically.
B-3
-------
TABLE B-l (continued)
Number
Fed Std
No. 75 la
AATCC 30-
1974
Date of
Issuance
65
74
Title
Other
Stitches, Seams, and Stitchings
Fungicides, Evaluation on Textiles:
Mildew and Rot Resistance of Textiles
Reference
Part No.
h
i
Available from General Services Administration, Business Service Center,
.Washington, DC.
American Association of Textile Chemists and Colorists, P.O. Box 12215,
Research Triangle Park, NC 27709 [reprinted in 1982 Book of ASTM Standards,
Part 32].
D 653 Definitions of Terms and Symbols Referring to Soil and Rock
Mechanics
D 1776 Conditioning Textiles for Testing
B.2.3 Terminology
Terms are defined as follows:
a. Permittivity, ¥ , (T ), n.—the volumetric flow rate of water
per unit cross-sectional area per unit head in the normal
direction through a geotextile.
b. Geotextile—any permeable textile used with foundation, soil,
rock, earth, or any other geotechnical material as an integral
part of a man-made project, structure, or system.
c. Hydraulic Conductivity, k , (LT ), n.—the rate of discharge of
water through a unit cross-sectional area of a porous medium
under a unit hydraulic gradient and standard temperature
conditions (at 20°C, or 68°F).
B.2.4 Summary of Method
This method describes a procedure for determining the permittivity of
geotextiles. The constant head test is performed by maintaining a head of
water on the geotextile throughout the test. The quantity of flow is measured
versus time.
B-4
-------
B.2.5 Uses and Significance
Since there are geotextiles of various thicknesses in use, to evaluate
them in terms of their hydraulic conductivities (permeability coefficients)
can be misleading. It is more indicative to evaluate the quantity of water
that would pass through a geotextile under a given head over a given cross-
sectional area. Permittivity is an expression of this; therefore it has been
selected for use in this method. The use of this test method is to establish
an index value by providing standard criteria and a basis for uniform
reporting.
Permittivity is used to evaluate the relative permeabilities of geotex-
tiles. Darcy's coefficient of permeability for geotextiles is difficult to
establish. Darcy's coefficient of permeability as related to geotextile
engineering may be computed from a permittivity value by multiplying the per-
mittivity by the nominal thickness of the geotextile.
Note 1: To determine the coefficient of the permeability, which is an
index value, the nominal thickness as determined in accordance with
ASTM D 1777 should be used. It is difficult to evaluate the pressure on the
geotextile during the test, thereby making it difficult to determine the
thickness of the fabric under these test conditions. Fabric thickness is
dimensionally insignificant in geotechnical terms.
B.2.6 Apparatus
The apparatus used in this method shall meet the following requirements:
The apparatus must be capable of maintaining a constant head of water on the
geotextile being tested.
In addition, the apparatus must not be the controlling agent for flow
during the test. It will be necessary to establish a calibration curve of
volumetric flow rate versus head for the apparatus alone in order to insure
compliance with this.
The device consists of an upper and lower unit that fasten together with
the geotextile specimen positioned in the bottom of the upper unit. There is
a standpipe for measuring the constant head value. An adjustable discharge
pipe would allow adjustment of the head of water on the specimen.
B.2.7 Sample Selection
For sample selection, use D 4354, Sampling Geotextiles for Testing,
except that the number of rolls selected as samples from any individual lot
shall not exceed 3, however.
B.2.8 Test Water Preparation
To insure the reproducibility of test results, the test water shall be
de-aired under a vacuum of 710 mm (28 in.) of Mercury (Hg) for a period of
time to bring the dissolved oxygen constant down to a maximum of 6 parts per
B-5
-------
million. The dissolved oxygen constant may be determined by either commer-
cially available chemical kits or by a dissolved oxygen meter.
Allow the de-aired water to stand in a closed storage tank under a slight
vacuum until the water reaches room temperature.
B.2.9 Specimen Preparation
To obtain a representative value of permittivity, four specimens are to
be obtained from each 1-m2 sample.
Refer to Figure B-l and select the specimens as follows:
FIGURE B-l
SPECIMEN PATTERN
1 m.
B-6
-------
Specimen A is taken at the center of the sample. Specimen B is to be taken at
one corner (center located 200 mm, or 8 in., from the corner). Specimen C is
taken midway between A, B, and D, an equal distance from A and C, and located
on the line with A, B, and C. Specimens shall be cut to fit testing
apparatus.
Place the specimen in the test apparatus selected for use.
Specimen conditioning will be accomplished by soaking the specimen rings,
with specimen attached, in a closed container of de-aired water at room con-
ditions for a period of 2 hr.
B.2.10 Suggested Constant Head Procedure
Assemble the apparatus with the specimen in place.
Backfill the system through the standpipe or discharge pipe, with
de-aired water. Backfilling in this manner forces any trapped air out of the
system and the geotextile. Backfilling is a technique of raising the water
level upward through the test specimen.
Close the bleed valve once water flows from it. Continue to fill the
apparatus with de-aired water until the water level reaches the overflow.
With water flowing into the system through the water inlet, adjust the
discharge pipe along with the rate of water flowing into the apparatus to
obtain 50-mm or 2-in. head of water on the geotextile. This is the head, h ,
under which the test will be performed.
Submerge a tube attached to a source of vacuum to the surface of the
geotextile. Apply a slight vacuum to remove any trapped air that may be in or
on the specimen. If necessary, readjust the head to 50 mm after removing the
vacuum.
Record the values of time, t ; quantity of flow, Q ; and water tempera-
ture, holding the head at 50 mm. At least five sets of data per specimen
should be collected. Determine an average value of permittivity for the
specimen from the five or more sets of data.
Repeat the procedure on the three remaining specimens that have already
been conditioned.
B.2.11 Calculations
Using Equation B-l, calculate the permittivity, f :
= QRfc/hAt Equation B-l
B-7
-------
where :
Q = quantity of flow, in cubic millimeters
h = the head of water on the specimen, in millimeters
A = cross-sectional area of test area of specimen in square millimeters
t = time for flow, Q , in seconds
R = temperature correction factor determined using Equation B-2
Rt = Ut/U20C Equation B-2
where
u = water viscosity at test temperature in millipoise
= water viscosity at 20° C (68° F) in millipoise
Using Equation B-3, calculate quantity of flow per time unit of flow
through a cross-sectional unit area, Q/tA:
Q/tA = ¥ h/R Equation B-3
Using Equation B-4, calculate the equivalent Darcy coefficient of
permeability or hydraulic conductivity, k :
k = L Y Equation B-4
where
k = equivalent Darcy coefficient of permeability
L = nominal thickness of a geotextile
Repeat for the five sets of data per specimen at 50 mm head.
Determine the average for the individual specimens tested.
Determine the average for the four specimens tested.
Determine the standard deviation and coefficient of variation for the
four specimens tested.
B-8
-------
B.2.12 Report
The following shall be-included in the report of the test results:
a. State that the specimens were tested according to this method.
b. State the results of the permittivity and quantity of flow per
unit of time through a cross-sectional unit area for the indi-
vidual specimens and the average of the four specimens tested.
Note 2: In the constant head procedure, if a head other than 50 mm is
used for laminar flow, state what the head value was.
c. State any variation from the described test method.
d. The equivalent Darcy coefficient of permeability can be reported
as per section B.2,10.
e. State the specimen size and water flow through dimensions of the
test apparatus.
B.2.13 Precision and Accuracy
Accuracy—No statement concerning accuracy is made at this time
because a statistically significant amount of data is not available for
evaluation.
Precision—Precision of this method is being established by ASTM
Committee D 35.
B.3 Percent Open Area Determination Procedure For Woven Geotextiles
A small section of the fabric to be tested should be installed in a
standard 5- by 5-cm (2- by 2-in.) slide cover so that it can be put into a
slide projector and projected onto a screen. Any method to hold the fabric
section and maintain it perpendicular to the projected light can be used.
The slide projector should be placed level to eliminate any distortion of
the fabric openings. After placing the slide in the projector and focusing on
a sheet of paper approximately 2.4 to 3m (8 to 10 ft) away, the opening
outlines can be traced.
Draw a rectangle of about 0.04- to 0.09-m2 (0.5 to 1.0-ft2) area on the
"projection screen" sheet of paper to obtain a representative area to test;
then trace the outline of all openings inside the designated rectangle.
After removing the sheet, find the area of the rectangle, using a
planimeter. If necessary, the given area may be divided to accommodate the
planimeter.
Find the total area of openings inside the rectangle, measuring the area
of each with a planimeter.
B-9
-------
Compute percent open by the equation:
r, „ . Total Area Occupied by Openings ,„,.
Percent Open Area = — — j-£ -* ^——=— x 100
r Total Area of Test Rectangle
B.4 New York State Department of Transportation Sieving Test For Particle
Retention and Equivalent Opening Size (EOS) of Engineering Fabrics
B.4.1 Introduction
This test involves sieving glass beads through an engineering fabric to
determine the equivalent diameter of its pore openings and its EOS.
B.4.2 Apparatus and Supplies
The following apparatus and supplies are required:
a. "Ro-Tap" or other rotary sieve shaker.
b. Pan, cover, and 8-in. sieves without wire screen, or with 1 in.
or larger openings.
c. Spherical glass beads in each of the following sieve sizes:
U. S. Bureau of Standards
Sieve Size No.
(ASTM E 11)
18-20
35-40
50-60
70-80
80-100
120-140
170-200
d. Balance (±0.01 g accuracy).
e. Engineering fabric samples 25.4 cm (10 in.) in diameter.
Available through: Ferro Corporation
Cataphote Division
PO Box 2369
Jackson, MS 39205
(601) 939-4631
B-10
-------
f. Four Staticmaster Ionizing Units.
B.4.3 Procedure
Using the engineering fabric samples of interest, do the following:
a. Install the Staticmaster units on the center of cover and
equidistant around the perimeter of the top sieve frame, as
shown in Figure B-2. Secure the fabric sample between two sieve
frames or in such a way that no beads pass between fabric and
frame. Record the weight of the fabric sample and frame.
b. Place 50 g (1.8 oz) of the smallest-size glass beads on the
fabric.
c. Install cover and pan on the sieve frames and place sieve nest
in the sieve shaker. Shake for 10 minutes.
d. Record weight of glass beads caught in pan.
e. If the fabric has beads trapped internally (possible for some
fabrics, especially felted nonwovens), break the sieve nest and
replace the fabric sample. If not, the same fabric sample may
be reused.
f. Repeat Steps b through d for increasing glass bead sizes.
g. If desired, a particle size (fabric opening) distribution curve
may be drawn for the fabric. However, the fabric EOS is the
U. S. Bureau of Standards sieve number for the first glass bead
size having 5 percent or less pass the fabric when sieving
successively coarser bead sizes. This value is approximately
the D size of the fabric.
Note 1: The U. S. Army Corps of Engineers procedure uses a 20-min
shaking time, which may give a different EOS value.
Note 2: After about 10 to 12 hr of shaking, glass beads should be
size-checked by sieving with conventional testing sieves. Broken or otherwise
out-of-size beads should be discarded.
Q
Available through: Staticmaster Ionizing Unit
Model No. 2U500
Nuclear Products Company
2519 North Merced Avenue
South El Monte, CA 91733
PO Box 5178
El Monte, CA 91734
(213) 283-2603
B-ll
-------
FIGURE B-2
FABRIC EOS SIEVING TEST APPARATUS
WOOD BLOCK-
COVER
STATIC MASTERS
1" MAX.
HANGER STRAPS
8 IN. SIEVE
WITHOUT FINE
WIRE MESH
FABRIC SAMPLE
SIEVE WITHOUT
FINE WIRE MESH
PAN
B-12
-------
B.5 U.S. Army Corps of Engineers-Type Engineering Fabric-Soil Gradient Ratio
Test Procedure
A constant-head permeability test shall be performed in a permeameter
cylinder similar to that shown in Figure B-3. Soil specimens to be tested
shall be representative in classification and density of those materials to be
protected. If actual soil specimens are unavailable or comparative perfor-
mance evaluations are desired, a test soil can be prepared using ASTM Standard
C 190 Ottawa 20-30 sand and Vicksburg, Mississippi, silt loess. The loess
should be premixed (dry) with the sand, and testing should be conducted with
increasing percentages of silt by weight (i.e., 0, 5, 10, 15, 20, 25,
30 percent, etc.).
A piece of hardware cloth with 6-mm (0.25-in.) openings shall be placed
beneath the fabric specimen to support it. The fabric and hardware cloth
shall be clamped between permeameter flanges and sealed so that no soil or
water can pass around the edges of the fabric. Care should be taken to avoid
getting any sealant used on the portion of the fabric inside the cylinder.
The soil specimen shall have a length of 102 mm (4 in.), and shall be
placed in a way that achieves a uniform specimen of the desired density.
Piezometer taps shall be placed 25 mm (1 in.) below the fabric and 25 mm
(1 in.), 50 mm (2 in.), and 75 mm (3 in.) above the fabric.
Tap water is acceptable for testing and shall be pumped slowly into the
bottom of the units to saturate the soil. An operating gradient to produce
optimum flow should be maintained by adjusting the outflow standpipe eleva-
tion. In comparative fabric evaluations, standpipe elevation should remain
constant for a given soil mixture of interest and all testing should be con-
ducted with the outflow standpipe above the top of the soil specimen.
After the test is started, a flow rate determination and piezometer
readings should be taken. Piezometer readings should be taken every
15 minutes until they stabilize; then another flow rate determination should
be made. After piezometer readings stabilize, the tap water shall be
permeated through the soil specimen for a continuous period of 24 hr. Final
piezometer readings and a flow rate determination should be made at the
end of the 24-hr period. The gradient ratio (GR) shall be determined from the
readings taken at the end of the 24-hr period.
The final GR is determined from the final piezometer readings and is the
hydraulic gradient through the lower 25 mm (1 in.) of soil plus fabric (i )
divided by the hydraulic gradient through the adjacent 50 mm (2 in.) of soil,
between 25 mm (1 in.) and 75 mm (3 in.) above the fabric (!„) (see Figure B-4)
such that :
GR - 1 Ll
(H. + HJ
L3)
2
B-13
-------
FIGURE B-3
DETAIL OF CONSTANT-HEAD PERMEAMETER TEST DEVICE USED FOR
GRADIENT RATIO TESTING
FROM CONSTANT
HEAD RESERVOIR^
DISCHARGE
4 IN. OR
LARGER
DIA.LUCITE
CYLINDER
1":
ENGINEERING
FABRIC
EC
r?
1
'
FE
\-
L-
(*
*
*
r£
4=
3-
if
L
>-,
^
i1
-*.
— — • ,
~"
k
]l
Ji
s
^
t:
!::>
< . •
*~' *
/-,
/
1
1
\ *•
',-
• •
t
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/
8
* ••:
" ':
' t '**
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^
rf
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r
4
51
J.
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—
s
p
•h
-
_
=jj
8*
1 "
-»* 1 "
7 „
5* i
1 "
3* '
1"
V
STAND PIPE
* PIEZOMETER NUMBER
(NOT TO SCALE)
If it is desired to determine the extent of silt migration, soil samples
should be taken over intervals of 0 to 6 mm (0 to 0.25 in.). 6 to 25 mm (0.25
to 1.0 in.), 25 to 50 mm (1.0 to 2.0 in.), and 50 to 76 mm (2.0 to 3.0 in.)
above the fabric. These samples may be oven-dried and sieved, and particle
size distributions may be compared with those of the pretest soil.
The initial and final permeability of the soil-fabric system, or any
intermediate values for the system, may be determined from the flow readings
and corresponding piezometer readings.
B-14
-------
FIGURE B-4
METHOD OF DETERMINING U. S. ARMY CORPS OF ENGINEERS SOIL-FABRIC
GRADIENT RATIO
FLOW
= L=1.0 IN.
GRADIENT RATIO =
L,
(H2*H3)
0-2+L3)
B-15
-------
APPENDIX C
GLOSSARY OF TERMS
ABRASION RESISTANCE - The ability of a fabric surface to resist wear by
friction.
ABSORPTION - The process of a gas or liquid being incorporated into a fabric.
ACID RESISTANCE - See "chemical stability."
ALKALI RESISTANCE - See "chemical stability."
AOS - See "apparent opening size."
APPARENT OPENING SIZE (AOS) - A term sometimes used instead of equivalent
opening size.
ARMOR - A protective covering.
BIAS - A direction diagonal to the warp and fill.
BIAXIAL TENSILE TEST - A tensile test in which a fabric specimen is subjected
to tensile forces in two directions 90 degrees to each other, usually the
machine and cross-machine directions.
BIOLOGICAL STABILITY - Ability to resist degradation from exposure to
microorganisms.
BLINDING - Plugging of a fabric by partial penetration of particles into
surface pores (i.e., the formation of a surface crust or cake).
BONDING - A process of binding fabric fibers by means of adhesive or by
welding with heat and pressure.
BURST STRENGTH - The resistance of a fabric to rupture from pressure applied
at right angles to the plane of the fabric under specified conditions,
usually expressed as the pressure causing failure. Burst results from
tensile failure of the fabric.
CHEMICAL BONDING - A bonding process in which the individual fibers in the
fabric web are cemented together by chemical interaction.
CHEMICAL STABILITY - Ability to resist chemicals such as acids, bases,
solvents, oils and oxidation agents, and chemical reactions, including
those catalyzed by light.
C-l
-------
CLOGGING - The plugging of a fabric by deposition of particles within the
fabric pores (other than blinding).
COMPRESSIBILITY - Property of a fabric describing the ease with which it can
be compressed normal to the plane of the fabric.
CONSTRUCTABILITY - See "workability."
CONSTRUCTION, FABRIC - The way the fibers, filament, and/or yarns are oriented
and bonded to produce a fabric.
CREEP, CYCLIC - Unrecoverable strain accumulated with repeated loading.
CREEP, STATIC - Increasing strain at constant stress.
CROSS DIRECTION (CROSS-MACHINE DIRECTION) - The axis within the plane of a
fabric perpendicular to the direction of motion in the final forming
step.
CUTTING RESISTANCE - The resistance of the fabric or fiber to cutting when
struck between two hard objects.
DENIER - A weight-per-unit-length measure of any linear material numerically
equal to the weight in grams of 9,000 m of the material.
EOS - See "equivalent opening size."
EPOXY BONDING - A bonding process in which the fabric web is impregnated with
epoxy resin that serves to coat and cement the fibers together.
EQUIVALENT OPENING SIZE (EOS) - A measure of the size of the largest openings
in a geotextile. The EOS is the "retained on" sieve size of narrowly
sized, rounded sand or glass beads, of which 5 percent or less by weight
passes through the fabric when the particles are shaken on the fabric in
a prescribed manner. The EOS is usually expressed as the U. S. Standard
sieve number, but it may also be expressed in millimeters.
FABRIC, BONDED - A textile structure wherein the fibers are bonded together
with an adhesive or by welding with heat and pressure.
FABRIC, KNITTED - Textile made up of loops of fibers connected by straight
segments.
FABRIC, NONWOVEN - A textile structure produced by bonding or interlocking of
fibers, or both, accomplished by mechanical, chemical, or solvent means
and combinations thereof, excluding woven and knitted fabrics.
FABRIC, WOVEN - A textile structure comprising two or more sets of filaments
or yarns interlaced in such a way that the elements pass each other
essentially at right angles and one set of elements is parallel to the
fabric axis.
C-2
-------
FATIGUE RESISTANCE - The ability to withstand stress repetitions without
suffering a loss in strength.
FELT - A sheet of matted fibers made by a combination of mechanical and
chemical action, pressure, moisture, and heat.
FIBER - Basic element of fabrics and other textile structures, characterized
by having a length at least 100 times its diameter or width that can be
spun into a yarn or otherwise made into a fabric.
FIBRILLATED YARN - A yarn made from a film which has been nicked and broken up
into fibrous strands that are then bundled together. The fibers can
still be partially attached to one another.
FILAMENT - A fiber of extreme length. Sometimes called "continuous
filaments."
FILL - Fibers or yarns placed at right angles to the warp or machine direction
in a woven fabric.
FILTER CAKE - A thin layer of fine soil particles accumulated in the soil
adjacent to the fabric as a result of smaller soil particles being washed
through the soil pores.
FILTRATION - The process of allowing water to easily escape from soil while
retaining soil in place.
FLEXIBILITY - The ability to bend around a small radius with the application
of only a small flexural stress. Low stiffness.
FREEZE-THAW RESISTANCE - Ability to resist degradation caused by freeze-thaw
cycles.
FRICTION ANGLE - An angle, the tangent of which is equal to the ratio of the
friction force per unit area to the normal stress between two materials.
GEOTEXTILE - Any permeable synthetic textile used in geotechnical engineering.
GRAB TENSILE STRENGTH - A modified tensile strength of a fabric. The strength
of a specific width of fabric together with the additional strength con-
tributed by adjacent areas. Typically, grab strength is determined on a
100-mm- (4-in.-) wide strip of fabric, with the tensile load applied at
the midpoint of the fabric width through 25-mm- (1-in.-) wide jaw faces.
GRADIENT RATIO - The ratio of the average hydraulic gradient across the fabric
and the 25 mm (1 in.) of soil immediately next to the fabric to the
average hydraulic gradient across the 50 mm (2 in.) of soil between 25
and 75 mm (1 and 3 in.) above the fabric, as measured in a constant-head
permeability test.
HEAT BONDING - A process by which fabric filaments are welded together at
their contact points by subjection to a relatively high temperature.
C-3
-------
KEVLAR - The registered trademark for a manufactured fiber in which the
fiber-forming substance is aramid or aromatic polyamide.
LATERAL DRAINAGE ABILITY - The capacity of a fabric to transmit water flow
within the plane of the fabric.
MACHINE DIRECTION - The axis within the plane of the fabric parallel to the
direction in which a fabric is processed onto rolls as the final step of
production.
MELT BONDING - See "heat bonding."
MODULUS - A measure of the resistance to elongation under load. The ratio of
the change in tensile load per unit width to the corresponding change in
strain.
MODULUS, OFFSET TANGENT - A tensile stress-strain modulus obtained using a
straight line to represent the stress-strain curve drawn parallel to and
offset by a prescribed distance from a line tangent to the initial
portion of the actual stress-strain curve.
MODULUS, SECANT - A tensile stress-strain modulus obtained using a straight
line (to represent the stress-strain curve) drawn from the origin through
a coordinate representing a stress measured at a specified strain.
MONOFILAMENT - A single filament of a man-made fiber, usually of a denier
higher than 15.
MULTIFILAMENT - A yarn consisting of many continuous filaments or strands.
NAP - A hairy or downy surface on a fabric.
NONWOVEN FABRIC - A textile structure produced by bonding or interlocking of
fibers, or both, accomplished by mechanical, chemical, or solvent means.
NEEDLE PUNCHING - Subjecting a web of fibers to repeated entry of barbed
needles that compact and entangle individual fibers to form a fabric.
NEEDLED FABRIC - A fabric constructed by needled punching.
PENETRATION RESISTANCE - The fabric property determined by the force required
to penetrate a fabric with a sharp pointed object. Initial penetration
is by separating the fibers. Further penetration is essentially a
tearing process.
PERCENT OPEN AREA - The net area of a fabric that is not occupied by fabric
filaments, normally determinable only for woven and nonwoven fabrics
having distinct visible and measurable openings that continue directly
through the fabric.
C-4
-------
PERMEABILITY (LONGITUDINAL OR IN PLANE) - The fabric property that permits a
fluid (normally water) to be transmitted in the plane of the fabric. See
"transmissivity."
PERMEABILITY (TRANSVERSE) - The fabric property that allows a fluid (normally
water) to pass through perpendicular to the plane of the fabric. See
"permittivity."
PERMEABILITY, COEFFICIENT OF - A measure of the permeability of a porous media
such as soil or geotextile to water. It is the ratio of discharge
velocity to the hydraulic gradient under laminar flow conditions. Also
referred to as the Darcy coefficient.
PERMITTIVITY - For a fabric, the volumetric flow rate of water per unit of
cross-sectioned area, per unit head, under laminar flow conditions, in
the direction perpendicular to the plane of the material.
PIPING - The process of soil removal resulting from seepage, in which
tunnel-like openings or pipes form in the soil mass.
PLANE STRAIN - A loading condition where strains in the plane of the fabric
occur in only one direction.
PLUGGING - The partial or total closure of fabric pores as a result of
particle or chemical deposition or biological growth within or on a
fabric. Plugging can consist of clogging, blinding, or both.
POLYESTER FIBER - A manufactured fiber in which the fiber-forming substance is
any long-chain synthetic polymer composed of at least 85 percent by
weight of an ester of dihydric alcohol and terephthalic acid.
POLYETHYLENE FIBER - A manufactured fiber in which the fiber-forming substance
is an olefin made from polymers or copolymers of ethylene.
POLYMER - A high molecular chainlike structure from which man-made fibers are
derived: polymers are produced by linking together molecular units
called monomers, consisting predominantly of nonmetallic elements or
compounds.
POLYPROPYLENE FIBER - A manufactured fiber in which the fiber-forming
substance is an olefin made from polymers or copolymers of propylene.
PORE SIZE - The size of an opening between fabric fibers. Because of the
variability of opening sizes for different fabrics, the equivalent
opening size (EOS) is used to determine the approximate size of the
largest pores of fabric.
PUNCTURE RESISTANCE - Resistance to failure of a fabric from a blunt object
applying a load over a relatively small area. Failure results from
tensile failure of the fibers.
C-5
-------
REINFORCEMENT - Strengthening of a soil-fabric system by contributions of the
fabric inclusion.
RESIN BONDING - A bonding process in which fabric web is impregnated with a
resin that serves to coat and cement the fibers together.
SCRIM - A woven fabric to which nonwoven fibers are bonded or needle-punched
to form a composite fabric.
SEPARATION - Function of fabric as a partition between two adjacent materials
to prevent mixing of the two materials.
SLIT-FILM FILAMENT - A filament with a width many times its thickness.
SOIL-FABRIC FRICTION - The resistance to sliding between engineering fabric
and soil, excluding the resistance from soil cohesion. Soil-fabric
friction is usually quantified in terms of a friction angle.
SPECIFIC GRAVITY - The ratio of the density of a fabric to the density of
water obtained by weighing both items in air. A specific gravity of less
than one implies that the fabric will float.
SPUN - a. A yarn (bundle of fibers) made from staple fibers interlaced and
twisted together.
b. The process of extrusion through a spinneret to make a filament.
SPUNBONDED - Any nonwoven fabric made in a continuous line process in which
filaments are extruded, drawn formed into a loose web, and bonded. The
bonding process can be mechanical, thermal, or chemical.
STAPLE FIBERS - Fibers having a short length, typically 25 to 100 mm (1 to
4 in.).
STIFFNESS - The ability of a fabric to resist bending when flexural stress is
applied.
STRENGTH - Load and failure. Depending on usage, load may be expressed in
stress, force per unit width, or force.
SURVIVABILITY - The ability of a fabric to be placed and to perform its
intended function without undergoing degradation.
TANGENT MODULUS - A tensile stress-strain modulus obtained using a straight
line (to represent the stress-strain curve) drawn tangent to a specified
portion of the stress-strain curve.
TENACITY, BREAKING - The breaking load of a fiber or yarn, in force per unit
linear density of the unstrained specimen, customarily expressed as
grams-force per denier (gf/den.) or grams-force per tex (gf/tex).
C-6
-------
KNOT BREAKING STRENGTH - The breaking strength of a strand with a knot tied in
the portion of the specimen between the clamps.
TAPE FILAMENT - A slit-film filament.
TENSILE MODULUS - See "tensile stress-strain modulus."
TENSILE STRENGTH - The strength shown by a fabric subjected to tension as
distinct from torsion, compression, or shear.
TENSILE STRESS-STRAIN MODULUS - A measure of the resistance to elongation
under stress. The ratio of the change in tensile stress to the
corresponding change in strain.
TENSILE TEST - A test that subjects fabric to tensile forces and measures
resulting stresses and strains, which are used to identify the stress-
strain behavior of the fabric. There are several variations of the
tensile test, the most widely used of which are the grab test, cut-strip
test, wide-width test, and the raveled strip test. All of the above
tests are considered uniaxial tensile tests.
TENSILE TEST, UNIAXIAL - A tensile test in which a fabric specimen is
subjected to tensile forces in one direction only.
THERMAL STABILITY - The ability of fibers and yarns to resist changes in
properties at extreme temperatures.
THICKNESS - The normal distance between two surfaces of a fabric. Thickness
is usually determined as the distance between an anvil, or base, and a
presser foot used to apply a specified compressive stress.
TOUGHNESS - The property of a fabric by which it can absorb work energy. It
is proportional to the area under the load-elongation curve from origin
to breaking point.
TRANSMISSIVITY - For a fabric, the volumetric flow rate of water per unit
width per unit head under laminar flow conditions in the longitudinal
direction through the material.
ULTRAVIOLET (UV) RADIATION STABILITY - The ability of fabric to resist
deterioration from exposure to sunlight. Actinic resistance.
WARP - Fibers or yarns parallel to the fabric machine direction in a woven
fabric.
WEB - The sheet or mat of fibers or filaments before bonding or needle-
punching to form a nonwoven fabric.
WEIGHT, FABRIC - The mass of a fabric expressed in weight per unit area.
C-7
-------
WICKING - The process whereby a fabric raises water above a free water surface
by capillary action.
WORKABILITY - The ease with which a fabric can be controlled, handled, laid
and seamed.
YARN - A generic term for a continuous strand of textile fibers, filaments, or
material in a form suitable for weaving or otherwise intertwining to form
a textile fabric.
.S.Government Printing Office: 1986—748-121/40678
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