EPA-600/8-77-006
JUNE 1977
THE FEASIBILITY OF UTILIZING
SOLID WASTES FOR BUILDING MATERIALS
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the "SPECIAL" REPORTS series. This series is
reserved for reports targeted to meet the technical information needs of specific
user groups. The series includes problem-oriented reports, research application
reports, and executive summary documents. Examples include state-of-the-art
analyses, technology assessments, design manuals, user manuals, and reports
on the results of major research and development efforts.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
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EPA-600/8-77-006
June 1977
THE FEASIBILITY OF UTILIZING
SOLID WASTES FOR BUILDING MATERIALS
Executive Summary
by
Gilbert Jackson
Sylvia Ware
Ebon Research Systems
Silver Spring, Maryland 20901
Contract Nos. 68-03-2460-1
68-03-2056
Project Officer
Robert E. Landreth
Solid and Hazardous Waste Research Division
Municipal Environmental Research Laboratory
Cincinnati, Ohio 45268
MUNICIPAL ENVIRONMENTAL RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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DISCLAIMER
Biis report has been reviewed by the Municipal Environmental Research
Laboratory, U. S. Environmental Protection Agency, and approved for publi-
cation. Approval does not signify that the contents necessarily reflect the
views and policies of the U. S. Environmental Protection Agency, nor does
mention of trade names or commercial products constitute endorsement or
recommendation for use.
11
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FOREWORD
The Environmental Protection Agency was created because of increasing
public and government concern about the dangers of pollution to the health
and welfare of the American people. Noxious air, foul water, and spoiled
land are tragic testimony to the deterioration of our natural environment.
The complexity of that environment and the interplay between its components
require a concentrated and integrated attack on the problem.
Research and development is that necessary first step in problem solution
and it involves defining the problem, measuring its impact, and searching for
solutions. The Municipal Environmental Research Laboratory develops new and
improved technology and systems for the prevention, treatment, and management
of wastewater and solid and hazardous waste pollutant discharges from munic-
ipal and community sources, for the preservations and treatment of public
drinking water supplies, and to minimize the adverse economic, social,
health, and aesthetic effects of pollution. This publication is one of the
products of that research; a most vital conimunications link between the
researcher and the user community.
This research has resulted in materials that can provide economical
housing for the homeless and help to solve solid waste disposal problems.
Francis T. Mayo, Director
Municipal Environmental
Research Laboratory
111
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ABSTRACT
This report is an executive summary of a two-phase study by Material
Systems Corporation initiated to research and develop building materials
containing organic and inorganic wastes and waste-derived products.
The first phase covered an extensive literature search to identify, re-
view and evaluate wastes with potential as matrices, reinforcements or fil-
lers in building composites. Following limited laboratory studies, two ma-
trices were selected for further study - an organic resin and an inorganic
matrix developed by Material Systems Corporation. Seven reinforcement can-
didates and five fillers were chosen for detailed evaluation in Phase II.
The second phase concentrated on evaluating the structural and aesthetic
properties of variously formulated composites containing a variety of solid
waste materials.
Satisfactory products could be made using both inorganic and organic
systems. Structural properties of several of the formulations were superior
to existing commercial products. Fire-resistance properties were also often
better than current fire-retardent materials. Economic analyses were per-
formed on the more structurally promising products and several commercially
viable materials appear possible.
The organic matrix containing rice hulls or peanut shells could be used
as the basis for structural board, sheet rock panel replacement, a lumber
substitute or fire doors. The inorganic matrix containing rice hulls as a
filler/reinforcement could be used as the basis for a foam material with
exceptional fire-withstanding properties. Possible products include fire-
rated partition walls, a fire door core, and floor/ceiling panels.
This report was submitted in fulfillment of Contract No. 68-03-2460,
Task 1, by Ebon Research Systems under the sponsorship of the U.S.
Environmental Protection Agency. Research data for the report was sum-
marized from a two-phase study conducted by Material Systems Corporation
for Contract No. 68-03-2056 under the partial sponsorship of the U.S.
Environmental Protection Agency. This report covers a period from
November 1973 to September 1974, and work was completed as of September
1975.
IV
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CONTENTS
Page
Foreword iii
Abstract iv
Figures vi
Tables vii
Metric Conversion Table ix
Acknowledgment x
1. Introduction 1
2. Conclusions 3
3. Recommendations 4
4. Evaluation of Materials 5
5. Products 51
Bibliography 67
Appendices
A. Bating System Criteria 71
B. Chemistry of the Furfural/Phenol Reaction 75
C. Economic Analyses 78
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FIGURES
Number Page
1 Ratings of Reinforcements with Inorganic Matrices 16
2 Ratings of Reinforcements with Organic Matrices 17
3 Tensile Strength of Machine Deposited Laminate 35
4 Effect of Fiber Length 36
5 Effect of Glass Content and Fiber Length 36
6 Stress-Strain Diagram for MSC Inorganic Matrix 39
VI
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TABLES
Nunber Page
1 Evaluation of Fillers 6
2 Source and Availability of Waste Fillers 7
3 Reinforcement Materials Considered 10
4 Reinforcement Ratings 12
5 Typical Costs of Reinforcement F.O.B. Source 14
6 Summary of Reinforcements, Phase II 15
7 Reinforcement Transportation Costs for 500 Miles 15
8 Source and Availability of Final Reinforcement Candidates .. 18
9 Matrices Considered, Phase I Ratings 20
10 Formulations for Run I 22
11 Evaluation of Run I - Formulations A&B 22
12 Formulations for Run II 23
13 Evaluations of Run II - Formulations D-K 23
14 Compositition of Hydrolysis/Condensation Mixtures 25
15 Formulation of Molding Mixtures 25
16 Corn Cob Based Composition 26
17 Rice Hull Based Compositions 28
18 Ash and Rice Hulls, Acid Treated for Short Periods 30
19 Properties of Molded Materials Without External Binder 32
20 Various Parameters in Inorganic Laminated Fabrication 37
VII
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TABLES (continued)
Number
Page
21 Formulations and Nail Retention of Nailable Wood
Replacements 41
22 Nailable Materials Containing Straw 42
23 Nailable Materials with Increased Amounts of
Casting Plaster and Glass Fibers 43
24 Nailable Materials Containing Gypsum Plaster 44
25 Compositions and Properties of Rice Hull Insulating
Materials 45
26 NBS Smoke Density Test Results 45
27 Flame Spread Test Results 46
28 Rice Hulls Syntactic Foams 48
29 Water Soak and Accelerated Weathering Data 49
30 Selected Formulations for Organic Materials 52
31 Comparative Costs of Products 54
32 Comparative Costs for Sheet Rock Substitutes 55
33 Design and Qualification Costs-Recommended Tests 58
34 Development and Manufacturing Costs 59
35 Products and Composition 60
36 Design and Qualification Costs-Inorganic Products 64
37 Development and Manufacturing Procedures-
Costs Inorganic Products 65
38 Comparison of Conventional Wood Shavings Plant with a
Rice Hull or Peanut Shell Plant 79
39 Estimate of Continuous Shape Facility 80
VZJLl
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METRIC CONVERSION TABLE
The units in this report are those found in the two technical reports
prepared by Material Systems Corporation. Engineering units as commonly used
in this report reflect current practice in this country.
1 short ton = 0.907 metric ton
1 long ton = 1.016 metric tons
1 Ib = 0.454 kilos
1° F = 5/9° C
1 Btu = 252 cals
1 mile = 1609 meters
1 inch = 2.54 on
IX
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ACKNOWLEDGMENT
Ebon Research Systems gratefully acknowledges the assistance of our
Project Officer, Mr. Robert E. Landreth. This summary is written from a
two-phase study done by Material Systems Corporation for the U.S. Environ-
mental Protection Agency.
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SECTION 1
INTRODUCTION
In recent years there has been an increasing focus on the development of
marketable products derived from waste materials in order to defray the esca-
lating costs of treatment and disposal. Various products obtained from waste
materials have received attention, including chemicals, food or feed materi-
als and energy. This report focuses on an on-going study to determine the
feasibility of utilizing solid wastes for building materials.
Material Systems Corporation (MSC) together with the Solid and Hazardous
Waste Research Laboratory (SHWRL), Environmental Protection Agency, has com-
pleted two phases of a suggested four phase study to evalute the technolog-
ical and commercial possibilities of waste - derived composites. The first
phase involved a joint and comprehensive literature search to identify wastes
with potential as building materials. Limited laboratory studies were con-
ducted on composite materials produced from the more promising wastes inves-
tigated.
A composite material was defined as a product containing a filler, a
reinforcement and a matrix. A filler is a small fiber, flake or particle
whose purpose is to displace the matrix from areas other than the reinforce-
ment matrix interface and to assist in reinforcement. The reinforcement is a
fiber, particle or a sheet whose primary purpose is to transfer load through
the composite. Integration of the three elements of the composite material
is accomplished by chemical adhesion by the matrix (binder) to the surfaces
of the reinforcement and the filler.
Various characteristics were considered desirable for the filler, the
reinforcement and the matrix. The wastes identified through the literature
search were evaluated against these desirable properties. A listing of the
evaluative criteria and the rating system used is found in Appendix A.
Filler materials reviewed included fly ash, crushed glass, phosphate
slimes, silicate waste, shredded refuse, waste plastic, wood bark, rice
hulls, taconite, red mud, coal waste foundry ash and sawdust.
Reinforcement materials reviewed included carbonized lignin, bagasse,
wheat straw, bark, kenaf, bamboo, wood chips, cotton waste and glass roving.
Sewage sludge, sawdust, rice hulls, plastic scrap and waste glass also re-
ceived attention as reinforcements.
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Matrix candidates derived from organic wastes of the agricultural and
lumber industries included rice hulls, peanut shells, wood chips, etc.
Matrices based on furfural phenol, dialdehyde starch/protein and cellulose
received attention. The furfural phenol compositions were studied in depth
during Phase II. MSC also investigated the use of an inorganic matrix pro-
prietary to the firm containing magnesium oxychloride which could be derived
from sea water.
As a result of Phase I research, it was determined that only two elements
of the composite material could be reinforcements. Filler material, except
for fly ash, could serve a dual role as reinforcement/filler. Thus, the
study was directed towards the evaluation of the matrix and reinforcement
materials only. During Phase II, various formulations of composite contain-
ing waste materials were evaluated for their structural properties, durabil-
ity and workability*
Phase II also involved a study of possible products that could be derived
from either the organic or inorganic matrix, and which contained wastes as
either matrix or reinforcement (or both). Several limited economic analyses
were performed to ascertain the commercial viability of any potential product
made.
Though a number of non-waste materials were also evaluated, the thrust of
the study was to utilize solid wastes. Through similar co-operative endeav-
ors between government agencies and private industry, it will be possible to
solve the mounting problems of solid waste management with ingenuity, envi-
ronmental integrity, and commercial sensibility.
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SECTION 2
CONCLUSIONS
Acid hydrolysis of waste materials containing pentoses (e.g. rice hulls,
corn cobs, oat hulls, etc.) results in formation of furfural. On addition of
phenolic wastes (wood wastes, wood pulp, etc.), a furfural/phenol resin is
produced in situ. Alternatively, acid treatment of wheat straw, rice hulls,
and corn cobs yields a binder with structural integrity on molding.
Several formulations with superior properties can be made through acid
hydrolysis of cellulose/pentose containing wastes with or without addition of
additional binder. Possible products to be developed from various organic
wastes (especially rice hulls) include:
structural board
replacement sheet rock
lumber substitute
fire doors.
Because of the high silica content of rice hulls, they impart a high de-
gree of fire resistance to composites.
The MSC proprietary binder containing magnesium oxychloride waste was
most successful in an organic matrix with rice hulls as filler/reinforcement
and inorganic fillers. By varying composition, it was possible to produce a
high density structural composite termed a laminate, and a low density core
composite similar to a foam.
The laminates evaluated demonstrated highly desirable structural proper-
ties, low cost and excellent fire-retardent properties. Possible products
based on inorganic matrix compositions include wood substitutes, fire rated
partition walls, fire door core panels and floor/ceiling panels.
Although waste materials from many sources were evaluated for effect-
iveness as filler/reinforcement/matrix, only a few of the materials tested
showed much promise. In addition to the rice hulls, corn cobs, wood wastes
and wheat straw mentioned above, fly ash displayed some potential as a filler
with both the organic and inorganic matrices. Though costing as much as the
currently used calcium carbonate filler, the use of fly-ash as a filler has
value as a waste disposal technique.
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SECTION 3
RECDMMENDATIONS
As several of the formulations evaluated showed commercial promise, it is
recommended that product development continue for those formulations showing
structural superiority and commercial viability. This development should in-
clude testing and evaluation to a sufficiently high level to assure qualifi-
cation for specific products under existing building standards and codes.
The insulating "foams" prepared from the MSC binder, rice hulls and in-
organic fillers should receive further attention. Procedures for manufacture
should be investigated, as well as possible marketing strategies for products
made from the inorganic matrix.
Structural boards based on a furfural-phenol resin, (produced from rice
hulls in particular) should continue in development. A similar formulation
shows potential as a sheet rock substitute and a fire door core. These three
potential products derived from organic wastes (rice hulls, peanut shells,
wood wastes, etc.) should be further developed.
Therefore, in order to completely explore the potential of waste
materials, it is proposed that two more phases should be funded:
(a) A Phase III study to develop and qualify the products mentioned
above for both organic and inorganic materials; and to construct
a transportable demonstrator 8' x 12' module of the test materials.
(b) A Phase IV study to evaluate the effect of weathering and aging on
the module and other qualified products of Phase III.
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SECTION 4
EVALUATION OF MATERIALS
FILLETS
The main purposes of a filler are to improve the properties and to reduce
the use of more expensive materials in the making of a matrix composite.
Calcium carbonate and alumina have been used as fillers in the past. This
study evaluated the possibility of utilizing wastes from the paper and wood
industries as well as municipal, industrial and mining wastes.
Fly ash, waste plastic, wood bark and rice hulls were chosen as primary
candidates for fillers. Crushed glass, shredded refuse, taconite, red mud,
phosphate slimes, silicate waste, coal foundry ash and saw dust were evalu-
ated also. Fly ash was the main candidate considered because of its uni-
versal availability, and because previous test on fly ash have indicated its
potential as a filler.
Filler candidates were evaluated against the following criteria:
(a) destructive reactivity and rate of reaction;
(b) temperature of decomposition (at least 750°F or 399°C);
(c) "grindability" and fineness of mesh;
(d) density;
(e) absence of aroma;
(f) performance with various matrix and reinforcement materials;
(g) availability.
The rating system may be found in Appendix A. Table 1 shows the ratings
of the fillers tested. These ratings are based on an examination of the lit-
erature. References may be found in the appropriate section at the back of
this report. Table 2 summarizes the source and availability of these possi-
ble fillers.
Initially, fly ash was employed as a filler for polyester fiberglass re-
inforced composities replacing the usual calcium carbonate filter. After
1500 hours of continuous exposure in an accelerated weathering test, the
mechanical and physical properties of the test filler were evaluated. The
fly ash filler exhibited properties equivalent to the calcium carbonate.
While the fly ash retained its appearance, a color problem could arise as
fly ash wastes range in color from dark grey to near black depending on their
source.
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TABLE 1
EVALUATION OF FILLERS
FILLER
Ash
Crushed glass
Phosphate slimes
Silicate waste
Shredded refuse
Waste plastic
Wood bark
Rice hulls
Taconite
Red mud (alum, ore)
Coal waste (recover
alumina)
Foundry ash
Saw dust
Reactive to Mud
Material
uecumposaoi. JL i ty
Grindability
555
54 5
345
545
233
315
414
533
4 35
435
555
555
325
•H
3
3
4
3
4
4
4
5
3
3
3
3
5
Absence of Aromc
5
5
2
2
2
5
2
5
5
2
5
5
5
Availability
8
5
2
2
7
1
8
6
3
2
2
2
4
0)
VJ
31
27
20
21
21
19
23
27
23
19
25
25
24
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TABLE 2
SOURCE AND AVAILABILITY OF VC\STE FILLERS
Candidates Evaluated
Source
Notes
Ash
Burning of coal,
generated by MSW
incinerators, metal
refining, etc.
Fly ash is readily produced throughout
U.S. with exception of W. Coast, Tx and
La. Fly ash is fine, inert and performs
well in composite, will not support
combustion - promising.
Has possible recycle value.Primary
supply is industrial. User would have to
crush. Does not support combustion -
promising.
Crushed glass
Industrial & MSW
Some studies have used it in brick
production. Slime has high moisture
content and must be dried. Because of
drying costs probably not economical.
Phosphate slimes
Phosphate mining in
Florida (only)
Silicate waste
Paper processing
Local sources
Supply limited due to lack of municipal
sorting and shredding facilities. May
react with matrices, doesn't age well,
variety of shapes causes problems.
Shredded refuse
MunicTpali ties
Smaller particle sized material used for
filler, larger sheets for scrap.
Flammability is a concern; mechanical,
surfaces and material matrix compatability
should be studied.
Waste plastic
MSW and industrial
waste
Fine material for filler. Flaranability a
problem. Widely available but density
differences with matrix could be a
problem.
Wood bark
Lumber industry
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TABLE 2 (continued)
Candidates Evaluated
Source
Notes
Rice hulls
Rice harvesting
May have to be crushed. High silicon
content advantageous as a filler, widely
available in parts of south. May be
flammable or harmed by environmental
factors.
Taconite
Iron ore processing
Localized availability, fine inert and
won't combust.
00
Red mud
Coal waste
Foundry ash
Aluminum processing
Localized in Texas, Ark., Ala., and La.,
smaller amount than taconite or phosphate
lines. Experimental concrete and brick
made from it. Fine, inert and won't
combust.
Potential to produce
alumina
Alumina filler used by MSC for 6 years -
experimental.
Arc furnaces, sand
reclaimers
Experimentally used as filler in epoxy
resins. Local supply (similar to fly
ash).
Saw dust
Lumber industry
Flammability a problem. Density
incompatibility with matrix a problem.
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It was noted that fly ash exhibited thixotropic behavior in the polyester
resin. This resulted in a condition of decreased viscosity or increased flow
with application of pressure or force. Therefore, the concentration was lim-
ited to 75 parts fly ash per 100 parts resin (c.f. calcium carbonate concen-
tration of 100 parts per 100 parts resin).
Though the optimum concentration of fly ash in the polyester matrix was
lower than the calcium carbonate in the same matrix, fly ash could be used in
equivalent amounts to calcium carbonate in MSC's inorganic matrix. The over-
all performance of fly ash as a filler with either matrix was very promising.
Fly ash obtained the highest rating of all the fillers evaluated, see Table
1. Calcium carbonate and fly ash cost about the same. Therefore, use of fly
ash as a filler is cost-effective only in that this use effectively disposes
of a waste material.
The ineffective fillers were sawdust, paper pulp, waste paper and comput-
er cards. They were tested with conventional organic systems, the waste
organic system and the MSC inorganic matrix.
As the Phase I study showed that filler material (except fly ash) could
serve a dual role as reinforcement, filler materials were not separately
evaluated in Phase II but were included as part of the reinforcement eval-
uation (q.v.).
REINFORCEMENT CANDIDATES
The reinforcing system can serve a variety of purposes:
(a) in an organic matrix it can both reinforce and/or supply the
resin;
(b) in an inorganic matrix it can both reinforce the matrix and/or
create voids in the matrix (syntactic foam).
During Phase I of this study, various wood, agricultural, industrial and
municipal wastes were evaluated as reinforcement candidates. Kenaf, bamboo
and glass roving which are not wastes were also evaluated. Reinforcement
candidates can be fibers, sheets or particles. Table 3 identifies the
materials evaluated by source, category and availability. The materials were
evaluated for the following properties:
(a) tensile strength and modulus;
(b) surface to volume ratio;
(c) length to width ratio;
(d) absence of aroma;
(e) availability;
(f) ccmpatability with matrix.
The rating system may be found in Appendix A. Table 4 summarizes ratings for
each of the reinforcement candidates evaluated. These ratings are based on
the literature search. References are collected at the back of this report.
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TABLE 3
REINFORCEMENT MATERIALS CONSIDERED
Material
Category
Source
Availability and Notes
Carbonized
lignin
Fiber
Graphite
fibers
Preliminary research stage/ not
considered
Bagasse
Pulp from
processed
cane sugar
Limited supply in U. S. highly
localized. Supports combustion.
Wheat straw
(ceral straw)
Cereal
harvest
Stiff wax layer causes bond
difficulty, combustible.
Bark
Lumber
industry
Inner materials can be used, short
fibers. Commercially developed.
Kenaf
Cordage crop
{jute sub-
stitute)
Central America, S.E. Asia. World
wide shortage, combustible, insect
prone.
Bamboo "
Wood chips "
Cotton wastes "
Bamboo
harvest
Lumber
industry
After gin
process
(hulls,
leaves,
stems,
seeds)
Difficult to fiberize, supports
combustion, insect prone. U.S.
limited.
Difficult to fiberize, supports
combustion. Affected by insects,
fungus, limited supply.
S.E. U.S., marginal properties,
affected by fire, insects, fungus.
Good supply.
10
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TABLE 3 (continued)
Material
Category Source
Availability and Notes
Glass roving
Not a waste
cornier cial
material
Good reinforcement at economic
values. As inorganic resists fire,
insects, fungi.
Paper
Sheet
Paperwaste Many uses, limited supply.
Affected by fire and environmental
factors.
Sewage
sludge
Particle Municipal
sanitation
sources
Low reinforcing qualities experi-
mental bricks made. Not economical
except for waste removal.
Sawdust
Particle
Lumber
industry
Full to low strength particle
board, large surface area requires
high matrix content, already well
used.
Rice hulls
Rice
harvest
Ash has 95% silica content
permitting high fire protection,
supply in California, Gulf Coast
Bricks made.
Plastic scrap
MSW and Size and shape cause problems.
industrial Primary supply is industrial.
waste Speciality application.
Waste glass
MSW and Crushed, similar shape problems to
industrial plastic. Experimentally reinforces
waste bricks and concrete, recyclable to
new glass.
11
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TABLE 4
REINFORCEMENT RATING
REINFORCEMENT
Carbonized lignin
Paper
Sewage sludge
Sawdust
Bagasse
Wheat straw
Rice hulls
Bark
Plastic scrap
Kenaf
Bamboo
Wood chips
Waste glass
Cotton waste
Glass roving
Tensile stre
5
5
1
1
4
4
1
4
4
4
1
4
4
4
5
Modulus
5
4
3
4
3
3
4
4
3
3
5
3
5
4
5
Surface/Volu
5
5
3
1
3
5
3
3
5
5
3
1
1
3
5
Length/Width
5
5
2
1
3
5
4
4
5
5
4
2
1
4
5
Absence of AJ
2
5
1
5
2
2
5
5
5
2
5
2
5
5
5
Availability
0
4
7
10
8
6
8
8
6
4
3
8
6
3
5
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Before final selection of materials for further study in Phase II, the
possible uses of the composite bricks were examined in relation to properties
exhibited by bricks made with specific fillers. The bricks could be used as
(1) primary structural materials; (2) bearing and framing materials; (3)
secondary structural materials; (4) floor surface materials.
Primary Structural Materials - These are materials that are used for trans-
ferring primary loads such as tension, compression and shear. Typical appli-
cations would be a load bearing wall surface, wall structural core such as a
corrugation, roof surfaces, etc. Typical axial stress levels would range
from 3,000 to 10,000 psi depending on design. Fiber reinforcements are the
primary candidates. Glass roving, although not a waste, is inexpensive,
available and can be used with any of the matrix sections. Paper is also an
acceptable reinforcement but is currently less available than glass roving.
Kenaf, sisal, jute and similar fibers-also perform well but are in short sup-
ply. The candidates chosen for Phase II based on all the above criteria were
glass roving and waste paper.
Bearing and Framing Materials - These materials are used to transfer joint
loads and close out openings. Typical applications are sill plates, window
and door frames, roof and floor beams. Typical axial and bearing stress
levels would range from 100 to 3000 psi depending on design. For this use
of brick, the candidates chosen for further study in Phase II were rice
hulls, bark, plastic scrap, .wood chips and cotton waste.
Secondary Structural Materials - These are materials used for non-load bear-
ing wall and ceiling panels.Typical axial stress levels would range from
100 to 1000 psi depending on the design. The candidates selected for further
study in this category were rice hulls, bark, wood chips and waste paper.
Floor Surface Materials - These materials are subjected to bearing and ab-
rasion.The reinforcing candidates selected were waste paper, rice hulls,
bark and wood chips.
Phase II - Screening Processes
The materials chosen from Phase I were initially screened to determine
the "acceptability" and "feasibility" of products produced from the materials
using both an organic and an inorganic matrix. "Acceptability" was defined
as the production of a material with properties achieving commercial stand-
ards. "Feasibility" of use indicated that it was possible to produce a com-
posite brick with a particular reinforcement candidate and either the organic
or inorganic matrix. Table 6 summarizes this data. After this initial
screening, the costs of the materials were determined F. 0. B. Source (see
Table 5).
Transportation costs are a function of material density — the lighter
the material, the higher the per pound cost. Therefore, it would be de-
sirable to density the lighter materials by compacting or baling where
practical.
13
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TABLE 5
TYPICAL COSTS OP REINFORCEMENT F. 0. B. SOURCE
Reinforcement $Cost/lb
Corn cobs 0.0075*
Straw 0.0020 - .OlOf
Rice hulls 0.0020 - .0025
Cotton waste 0.0020 - .010
Peanut shells 0.0075}
Wood bark 0.01
Saw dust 0.01
Pine shavings 0.01
Alder shavings 0.01
Douglas fir shavings 0.01
Redwood shavings 0.01
Ash shavings 0.01
Plastic scrap Unable to establish a cost
Reject styrofoam beads 0.25
Glass fibers 0.43
Silvacon 412 0.0465
*' Cornnuts, Inc. - Oakland, California
t The cost would vary with demand. It will not be less than rice
hulls or more than wood shavings.
} Gold Kist Feed Mill Company
This is a nominal cost paid by shipboard manufacturer. The cost
may vary 10% with supply and demand.
A 500 mile transportation radius was selected as this would provide a
factory with 785,400 square miles of producing waste sources. This area was
considered more than adequate to supply necessary reinforcement material.
Table 7 shows the transportation costs per pound for several reinforcement
candidates gathered within this 500 mile radius.
The reinforcement candidates were rated according to product potential.
Figure 1 illustrates the ratings for reinforcements used with inorganic ma-
trices and Figure 2 shows the ratings with organic matrices. The ratings
were based on eight criteria listed in each figure and graded from 0 to 4.
While a score of 32 represented the maximum points obtainable, the value of
20 points was established as the "preferred" level of selection. A rating of
16 was considered "acceptable" and represented "average reasonable" poten-
tial. For an individual criterion, a rating of 2 points represented "reason-
able" potential. Nail retention was used as a criterion for applicability to
conventional construction; the other criteria represented requirements for a
feasible product.
14
-------
TABLE 6
SUMMARY OF REINFORCEMENTS, PHASE II
Used with
Inorganic Matrix
FeasibleAcceptable Feasible Acceptable
Reinforcement:
Used with
Organic Matrix
Agricultural Waste
Corn cobs X
Straw X
Rice hulls X
Cotton waste X
Peanut shells X
Industrial Waste
Wood bark X
Saw dust X
Pine shavings X
Alder shavings X
Douglas fir shavings X
Redwood shavings X
Ash shavings X
Plastic scrap
Reject styrofoam beads
Reject graphite fibers
Sisal scrap
Fly ash
Commercial Waste
Waste paper X
Paper pulp
Computer cards
Non-Wasjbe
Glass fibers
Silvacon 412 X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
TABLE 7
REINFORCEMENT TRANSPORTATION COSTS FOR 500 MILES
REINFORCEMENT
Corn cobs
Rice hulls
Peanut shells
Wood shavings
$Cost/lb.
0.0062 - 0.0125
0.014
0.013
0.010
15
-------
Figure 1
Ratings of Reinforcements with Inorganic Matrices
35
30
tn
Criteria
availability
ease of drying
nail retention
dimensional stability
ease of processing
density
flammability
a\
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4J
« 25,
20
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acceptable
all respects
acceptable
more work
reasonable
potential
poor
prospects
unaccep_t-
able
Inorganic Binders/Waste Products Composites
(Screening Phase)
-------
Figure 2
35
30
25
20
15 I
10
5 -
Ratings of Reinforcements Used with Organic Matrices
Criteria
availability
pentosan content
nail retention
dimensional stability
ease of processing
density
flammability
total materials cost
CO
o
o
G
O
U
If
fd
M
4J
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U
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jjppr
prospects
unacce^t"
able
Organic Binders/ Waste Products Composites
(Screening Phase)
-------
After thorough evaluation and review, it was concluded that rice hulls,
peanut shells, corncobs, woodshavings and silvacon would be the best candi-
dates as reinforcements with an organic matrix. Cotton waste should only be
considered a possible reinforcement material if the disposal problems are
sufficient to counter poor characteristics displayed (see Matrix Section).
Straw must be pretreated to destroy or break up its resistant surface before
it can be used as a reinforcer. Waste paper cannot generate furfural and
therefore by itself was not effective. Even when used in combination with
other materials, it showed little promise.
Rice hulls are the best reinforcement for an inorganic matrix. Plastic
scrap and reject styrofoam beads show definite promise but are limited in
supply. In the distant future, sorting of MSW could supply a quantity of
plastic scrap. Fly ash, sisal scrap and silvacon are of lesser interest and
all other candidates should be disregarded.
TABLE 8
SOURCE AND AVAILABILITY OF FINAL REINFORCEMENT CANDIDATES
Reinforcement
Corn cobs
n
Rice hulls
H
Quantity
Source
Cotton waste
Peanut shells
n
Wood shavings
Silvacon
Plastic scrap
Reject styro-
foam beads
Fly ash
1,500 - 2,000 tons/yr
Similar
3,000 tons/month
+150 tons/month
25,000 - 30,000 tons/yr
Similar
Unknown
350,000tons/yr
3,000 tons/month
Unlimited
Unlimited
Unlimited
Limited
30 x 10 tons/yr
Cornnuts Inc., Oakland, Calif.
Seed milk in Calif, and Midwest
Comet Rice Mills, Houston, Texas
C.E. Grosjean Rice Milling Co.,
San Francisco, Calif.
Shifflet Bros., Grindley, Calif.
Louisiana and Texas
Unknown
Texas, Louisiana, Georgia, Alabama,
Arkansas, Mississippi, Florida
Gold Kist Seed Mill, Comanche, Texas
Northwest,%South and Southeast
Weyerhauser
Unknown
Unknown
Coal-fired furnaces
18
-------
MATRICES
The matrix is the binder which integrates the filler and the reinforce-
ment and causes the composite to perform as a single material. This is
accomplished by chemical adhesion of the matrix to the surface of the rein-
forcement and the filler.
A number of both organic and inorganic matrices were considered: the
organic matrices to offer versatility in processing, and the inorganic to
provide a high degree of non-flammability to the final product.
In the Phase I evaluation, candidates included dialdehyde/protein
starches, furfurals, cellulose, phenols and inorganics (cements). These
materials were rated on:
(a) curability temperature;
(b) absence of aroma;
(c) processability (time required, pressure and temperature);
(d) physical state;
(e) toxicity;
(f) decomposability;
(g) color;
(h) availability.
A detailed explanation of the meanings assigned to these terms and the
rating system employed is found in Appendix A. Table 9 summarizes the rat-
ings and gives the final scoring for the matrices initially considered.
References to the literature on which these ratings are based are found at
the back of this report.
It was concluded that furfurals, phenols and inorganics should be further
studied in Phase II.
I. Organic Matrix
Some of the most versatile and strong resins commercially available are
based on the condensation polymerization of a phenol with an aldehyde.
Though formaldehyde is normally used, it is possible to replace this chemical
with other aldehydes. In practice this is rarely done because of expense and
technological difficulties in processing. Furfural and furfuryl alcohol
based resins are in use and have been utilized as molding compounds and
matrices for reinforced composites. Furfuryl alcohol is made by hydrolysis
and dehydration of pentoses in rice hulls, corn cobs, oat hulls, manures,
etc. to produce furfural which is then hydrogenated. However, furfural is
itself highly reactive and known to condense with phenols to give resinous
products.
It would be very useful to obtain a construction material based on
furfural-phenol resins obtained from waste materials without the cost-
increasing step of isolating the reactants. The in situ reaction of the
furfural generated would also eliminate the cost of catalytic hydrogenation
19
-------
TABLE 9
MATRICES CONSIDERED, PHASE I RATINGS
Processabili ty
Matrix
Dialdehyde/protein
starches
Furfurals (manure)
Furfurals {rice hulls,
bagasse)
Inorganics (cement)
Cellulose (reactants)
Phenols
Lignin
£
••H
rH
•H
••a
5
5
5
5
3
3
3
X
14-1
o
0)
o
§
CO
3
5
4
4
5
4
4
4
I
1
5
5
1
5
5
5
o>
10
-------
with waste materials chosen for reinforcement and filler candi-
dates;
(2) a three step in situ formation of furfural with addition of
organic resins or resin precursors;
(3) a simpler two-stage process for in situ formulation of furfuryl
from waste without added organic resins or resin precursors.
These three approaches are analyzed below:
(1) Development of a matrix using using a commercial furfural source
Referring to the chemistry outlined in Appendix B, the formu-
lation of the resin was tested using the Quaker Oats "Quacor"
furfuryl alcohol-based resin. This gave the opportunity of
testing a resulting matrix material theoretically similar to the
expected in situ resin produced by either the two or three stage
process.
A series of commercial formulations were prepared. Two ex-
perimental runs were conducted on the MSC continuous process ma-
chinery. The first run used resin mixes twice as viscose as that
of the production polyester mix. Line speed was 3 feet per minute
and production speed was between 5 and 10 feet per minute. Three
ovens were used at temperatures of 77°C, 82°C, and 99°C respec-
tively. None of the formulations was fully cured after treatment
in oven #3. After overninght air cure and post curing at 127°C
and 141°C for ten minutes at each temperature, A and B were fully
cured. Table 10 shows the results of evaluated variations in
fillers and catalyst. Oven #1 was set at 71°C; oven #2 at 102°C
and oven #3 at 177°C. All samples appeared well cured after oven
#3 though some samples were post cured at 177° for two hours. The
results of mechanical and flame spread test are shown in Table
11.
It was concluded that furfural is processable on the produc-
tion system and will develop a product equivalent to or superior
to the presently qualified product. The studies indicated no
insurmountable difficulty in processing composites based on matrix
resins using the furone ring system.
To prepare an aesthetic surface for use as exterior wall
panels, it was found most effective to add crushed rock, glass,
plastic, etc. to the composite on the belt, and then cure the
entire system.
21
-------
N)
NJ
TABLE 10
FORMULATIONS FOR RUN I
B
Resin
Solvent
Catalyst
Filler
Quacor RP1001 - 2000g
Furfuryl alcohol - lOOg
Quacor RP104B - 60g
Huber 35* - 1200g
(75% Ti02 )
(25% Furfuryl - 25g
alcohol)
*Huber 35 is a fine clay
Quacor RX300
Furfuryl alcohol
Quacor RP104B
Huber 35*
(75% Ti62 )
(25% Furfuryl
alcohol)
with acidic pH
TABLE 11
- 2000g
- lOOg
- 60g
- 1200g
- 25G
Quacor EP100A
Furfuryl alcohol
Quacor RP104B
Casting Plaster
(75% Ti02 )
(25% Furfuryl
alcohol )
- 2000g
- lOOg
- 60g
- 1800g
- 25g
EVALUATION OF PUN I - FORMULATIONS A and B
A
B
Density Smoke
.052 lb/m3 5
.069 lb/m3 0
Conmercial
Building
Materials 400
Flame Spread %
25
17
100
Glass Fiber
29
28
Tensile
5240 psi
5544 psi
2000 - 5000
psi
-------
Form.
Resin
TABLE 12
FORMULATIONS FOR RUN II
Solvent
Filler
Catalyst
D Quacor
E
TJ< tl
G Quacor
H Quacor
I
J
K
RP100A (100) Furfuryl Alcohol (5) Huber 35 (60) RP104B (3)
(100)
(100)
RX300
RP100A " "
" (100)
(100)
n (100)
(5) " " (80)
(5) " " (100)
(5) " " (60) "
(5) C-31* (60)
(5) " " (60) "
(5) Huber 35 (60)
(5) " " (60)
(3)
(3)
(3)
(3)
(4)
(4)
(4)
*C-31 is alumina hydrate
Form.
D
E
F
G
H
I
J
K
Commercial
Building
Material
TABLE
EVALUATION OF RUN II
Flame Spread
As Cured Post Cured
37 16
20 12
20 25
16 18
31 18
33 18
33 27
22 18
100
13
- FORMULATIONS D-K
Tensile
As Cured Post Cured
6850 8015
5480 6020
3680 4050
7380 6310
5080 4890
4175 4780
3490 3560
7630 7600
2000-5000
23
-------
(2) Three stage process of in situ formation with additives
As indicated in Appendix B, furfural can be derived from rice
hulls or corn cobs by acid hydrolysis under pressure. The purpose
of this study was to:
(a) determine if pressure was really necessary;
(b) determine yield of furfural at lower pressures.
The additives were used to interact with the furfural, and/or
stimulate furfural formation, and/or reinforce and absorb excess
furfural.
It was theorized that a novolak resin would be formed in situ
by refluxing rice hulls (source of furfural) with wook bark
(source of phenol) at atmospheric pressure. Addition of a fur-
fural or hexamethylene tetramine "seed" would produce further
cross linking.
After preparation, rice hulls were refluxed with dilute hydro-
chloric acid followed by addition of phenol and further refluxing.
The mix was air dried; hexamethylene tetramine was added and the
resulting material molded at 150°C and 250 psi. There was no
flow, the molding was resin starved and easily breakable. A
second series of experiments was carried out refluxing the rice
hulls in dilute hydrochloric with phenol present initially.
Molding trials were carried out on the hydrolysis mixtures
after addition of Silvacon 412 as a filler and 10% dry weight of
chopped glass fibers as reinforcement.
Tests performed on the hydrolysis mixture did not determine
the exact yield of furfural. However, it was concluded that with
a roughly 3-6% MCE solution and refluxing at 100° for 15-20 hours,
it was possible to produce enough furfural to give a moldable
material. A lower acid concentration (1%) and shorter reflux time
(3-5 hours) did not produce a moldable product.
Successful resins were also obtained by refluxing rice hulls
or corn cobs without bark or other phenolic materials present.
After hydrolysis, Silvacon 412 was added to absorb excess furfural
and act as a filler. Addition of shredded newspaper reinforced
the composite which was cured for 20 minutes at 150°C and 500 psi.
The effect of different concentrations of wood bark on the
hydrolysis mixture was also investigated. Addition of hexamethyl-
ene tetramine improved the integrity of the moldings. Table 14
gives various formulations for the hydrolysis mixture and Table 15
gives formulations for various molding mixtures.
24
-------
TABLE 14
COMPOSITION OF HYDROLYSIS/CONDENSATION MIXTURES
Mixture
Nunber
30
26
23
25
29
28
24
27
Corn cobs Rice hulls Wood bark HCL
(g) (g) (g) (ml)
120 - 12
120 - 60 12
120 - 90 12
120 - 120 12
30 - 3
30 15 3
30 22.5 3
30 30 3
Water Silvacon*
(ml) 412 (g)
200 50
200 70
200 70
220 60
115 40
115 30
115 30
115 30
*Added after completion of hydrolysis
Sample
A
B
C
Above
A
B
C
D
E
Above
TABLE 15
FORMULATION OF MOLDING MIXTURES
Wet Mixture* Furfural Furfuryl
(g) (ml) Alcohol (ml)
35
35 - -
35 1 -
for mixtures 29, 30.
24 -
_ - -
24 1
24 1
24 - 2
for mixtures 23, 24, 25, 26, 27, 28.
Newspaper
(g)
3
2
-
2
2
2
2
25
-------
The above mixtures produced cross-linked resins, insoluble in
water, and retaining much of their strength after 24 hours water
immersion. An attempt to produce moldings by adding alkali after
initial acid hydrolysis was not successful, producing water-
soluble resins.
Hie yield of furfural was investigated under various reaction
conditions including reaction time, change of acid and mechanical
agitation. Hie amount of furfural was determined by titrametric
analysis using sodium bisulfite.
The yields of furfural were studied after 3, 10 and 20 hours.
It is not certain that the reaction came to equilibrium kinetical-
ly. After 20 hours, rice hulls gave a yield of 4.13% furfural and
corn cobs yields of from 3.269% to 10.93%. Mechanical stirring
did not improve yield of furfural. Replacing hydrochloric acid
with sulfuric acid did not alter the yield of furfural produced
from rice hulls. The yield from acid hydrolysis of corn cobs was
50% lower with the sulfuric acid.
All compositions discussed were molded, dried and tested (see
Table 16). It was found that:
(1) Modulus of rupture increased with density for mixtures
containing no wood bark, and a high proportion of wood
bark, rice hulls/wood bark, and corn cobs/wood bark;
(2) Addition of newspaper did not seem to improve modulus of
rupture and in some cases even lowered density and
strength;
(3) Addition of furfural (samples designated C) or addition
of furfuryl alcohol (samples designated D, E) did not
improve the strength.
It was concluded that future work should concentrate on the
processing of materials without the use of external binders.
TABLE 16
GOTO OOB BASED COMPOSITION
Width Thickness Weight Density Flexural Modulus of
Sample (In.) (In.) (g) Load (Ibs) Rupture (psi)
30A (1) 0.994 0.180 19.3 1.09 8.0 1490
30A (2) 0.985 0.163 17.1 1.07 5.0 1146
30B (1) 0.985 0.212 25.3 1.12 9.0 1219
26
-------
TABLE 16 (continued)
Sample
Width Thickness
(In.) (In.)
Weight
Density Plexural Modulus of
Load (Ibs) Rupture (psi)
30B (2)
30C (1)
30C (2)
26A (1)
26A (2)
26B (1)
26B (2)
26C (1)
26C (2)
26D (1)
26D (2)
26E (1)
26E (2)
23A (1)
23A (2)
23B (1)
23B (2)
23C (1)
23C (2)
23D (1)
23D (2)
23E (1)
23E (2)
25A (1)
0.994
0.985
0.993
0.996
1.000
1.000
0.994
0.999
0.995
0.999
0.993
0.998
0.994
0.995
0.998
1.000
1.002
1.003
1.004
1.000
0.996
0.996
1.000
0.997
0.208
0.190
0.193
0.254
0.255
0.290
0.285
0.255
0.253
0.282
0.280
0.310
0.312
0.228
0.233
0.235
0.240
0.237
0.239
0.284
0.279
0.286
0.290
0.299
23.1
19.7
19.5
24.7
24.8
27.5
27.3
25.7
24.8
27.5
27.5
29.4
28.7
25.2
25.2
24.9
24.5
25.2
25.0
28.6
28.6
29.2
29.1
27.2
27
1.13
1.04
1.03
0.99
0.99
0.96
0.97
1.02
1.00
0.99
1.00
0.96
0.94
1.12
1.10
1.08
1.04
1.08
1.06
1.02
1.03
1.04
1.02
0.92
7.8
8.4
8.2
8.. 4
8.4
10.7
10.7
12.5
10.6
15.5
16.7
18.9
16.4
14.0
11.4
10.7
10.1
10.6
12.0
18.2
17.4
18.4
23.7
8.0
1084
1417
1320
781
775
763
790
1154
1001
1171
1291
1180
1010
1624
1258
1168
1052
1131
1255
1357
1344
1353
1694
538
-------
TABLE 16 (continued)
Sample
25A (2)
25B (1)
25B (2)
25C (1)
25C (2)
25D (1)
25D (2)
25E (1)
25E (2)
Width
(In.)
1.000
0.998
1.004
0.999
1.000
0.998
1.000
1.000
0.998
Thickness
(In.)
0.296
0.306
0.310
0.298
0.299
0.321
0.322
0.370
0.370
Weight
(g)
27.2
28.9
28.9
28.2
27.9
29.9
29.9
31.7
32.6
TABLE
Density
0.93
0.96
0.95
0.96
0.95
0.95
0.92
0.87
0.89
17
Flexural
Load (Ibs)
7.4
9.9
8.7
9.7
11.6
12.4
13.0
12.6
13.4
Modulus of
Rupture (psi)
505
634
544
659
780
722
752
553
587
RICE HULL BASED COMPOSITION
Sample
A (1)
A (2)
B (1)
B (2)
C (1)
C (2)
A (1)
A (2)
B (1)
B (2)
C (1)
Width
(In.)
0.985
0.985
0.997
1.002
1.000
1.004
0.985
0.985
1.000
1.000
1.005
Thickness
(In.)
0.207
0.207
0.323
0.318
0.210
0.214
0.222
0.218
0.350
0.346
0.302
Weight
(g)
23.5
22.9
21.6
30.7
22.1
23.9
21.5
20.8
34.9
34.4
33.7
28
Density
1.15
1.12
0.99
0.98
1.07
1.09
0.98
0.97
1.01
1.01
1.13
Flexural
Load (Ibs)
13.5
12.5
16.5
13.1
7.1
9.7
7.5
5.5
20.0
26.0
23.51
Modulus of
Rupture (psi)
1918
1776
951
744
969
1272
913
694
980
1303
1538
-------
TABLE 17 (continued)
Sample
C (2)
D (1)
D (2)
E (1)
E (2)
A (1)
A (2)
B (1)
B (2)
C (1)
C (2)
D (1)
D (2)
E (1)
E (2)
A (1)
A (2)
B (1)
B (2)
C (1)
C (2)
D (1)
D (2)
E (1)
Width
(In.)
0.996
1.004
1.000
1.005
1.000
0.995
1.000
1.000
1.001
1.001
1.000
1.002
1.004
1.007
0.998
1.003
1.000
1.002
1.006
1.001
1.003
0.999
1.002
1.006
Thickness
(In.)
0.290
0.315
0.315
0.372
0.370
0.260
0.280
0.330
0.340
0.322
0.317
0.317
0.317
0.373
0.372
0.298
0.292
0.321
0.320
0.356
0.356
0.373
0.377
0.344
Weight
(g)
30.7
30 3
29.1
33.6
33.6
27.2
27.2
34.1
37.7
32.5
32.5
30.8
30.6
33.5
34.0
29.1
28.0
31.4
31.5
34.4
32.2
33.3
37.8
33.1
29
Density Flexural Modulus of
Load (Ibs) Rupture (psi)
1.08
0.98
0.94
0.92
0.92
1.06
0.99
1.05
1.12
1.03
1.04
0.99
0.98
0.91
0.93
0.99
0.97
0.99
1.00
0.98
0.92
1.04
1.02
0.98
21.51
14.01
12.75
15.1
17.0
16.1
13.2
17.5
16.6
14.7
14.5
14.7
14.7
12.4
18.2
9.5
8.5
13.0
14.7
10.5
10.7
23.6
23.0
19.5
1540
846
770
652
745
1438
1014
964
862
853
866
879
877
530
575
640
598
755
859
496
507
1020
969
983
-------
(3) Two step process of in situ formation of furfural from wastes without
additives.
It was discovered that after acid treatment cellulose containing mate-
rials (with pentosans) yield a binder during molding. Initial work was
conducted on wheat straw, rice hulls and corn cobs. Acids used were 3%
solutions of hydrochloric acid, phosphoric acid, oxalic acid, chromic
acid, p-toluene sulfonic acid and hydrochloric acid with 1% aluminium
chloride. Die materials tested were soaked in acid solution for an
arbitrary 30 minutes after which they were dried at room temperature or
oven-dried at 50-60°C. The treated materials were molded for 5 minutes
at 120-150°C and 500 psi.
The p-toluene sulfonic acid was most successful; oxalic acid and boric
acid failed to catalyze binder formation; chromic acid and the hydro-
chloric acid + aluminum chloride mixture caused charring. The effect of
shorter acid treatment periods is shown in Table 18.
TABLE 18
ASH AND RICE HULLS, ACID TREATED FOR SHORT PERIODS
Sample Material
Acid Treat- Molding
Time ment Time Temp
(Min.) Temp (°C) (Min.) (°C)
Pres-Modulus of
sure Den- Rupture
(Psi) sity (Psi)
YP-64
YT-64
MT-64
YP-64
Ash
Ash
Ash
Ash
+
+
+
+
•jo. u -on
*>o n^irviyi
3% H3PO4
00. a rjf\
•jf n_cv>
O
-------
Cotton waste was successfully molded with hydrochloric acid, phosphoric
acid and p-toluene sulfonic acid. The main source of binder seemed to be the
dried stalks and flower pods. Wheat straw composites did not weather well
containing a great deal of pith not removed by initial blending. Wood wastes
gave excellent results on treatment with phosphoric acid giving moldable
materials without need of an added binder. Wood wastes of particle size less
than 4 mesh gave the best final products.
The molded wood specimens and rice hull moldings were submitted to an
accelerated weathering test carried out in an Atlas Electric Weatherometer
Model HVDC. The samples were compared to commercial and industrial grade
particle board (44 Ib/ft3 and 55 Ib/ft3 density respectively). The
properties compared well, though the specimens were not intended for external
use. Samples with mixed size particles showed the best surface condition
after weatherometer testing.
Two flammability tests were performed on:
(a) industrial grade particle board (d=551b/ft3) (the control)
(b) molded rice hulls (YT-46);
(c) molded white pine (yr-58);
(d) molded ash (YT-64).
The flame spread test results showed that the molded rice hulls were the
least flammable product. The industrial particle board was the most flamma-
ble of the samples, see Table 19. The molded wood samples were self-extin-
guishing. The smoke generated by the molded rice hulls was very low. Again,
the particle board produced the most smoke.
Nail and screw retention tests of the wood waste moldings were conducted
to determine material workability. The results were equivalent to those for
industrial particle board. Rice hull moldings showed inferior nail and screw
retention. A summary of all properties of the molded materials is found in
Table 19.
The molded wood waste and rice hulls showed good mechanical properties
without an external binder, when molded at pressures above 300 psi. A
pressure of 500 psi gave the best results. It was felt that the addition of
an external binder might reduce the neeed for high pressure. The binder
should be reactive at low pH and be inexpensive.
Wood particles and rice hulls were soaked in a 10% aqueous solution of
MT-115 (ITT Rayoner). The excess was decanted, the particles dried, soaked
in 3% phosphoric acid and dried following removal of excess acid. The parti-
cles were molded at 150°C and 500 psi for five minutes. Both rice hulls and
ash particles receiving the same treatment were dry and broke more easily
than without addition of MT-115.
Soaking in a solution of Raylig-Al (ITT Rayoner) and 3% phosphoric acid
was followed by molding at 150°C and 500 psi for five minutes. Though rice
hulls showed 30% improvement in strength, when the molded specimens were put
into water, they softened and were easily broken.
31
-------
TABLE 19
PROPERTIES OF MOLDED MATERIALS WITHOUT EXTERNAL BINDER
NJ
Material No
Waste
Material
Acid
Molding 0.2
Temp. JC
Time (min.)
Pressure
(psi)
Density
(9/cm3)
Modulus of
Rupture
(Psi)
Straight
Nail Pull
Straight
Screw Pull
(lb.)
Flame
Spread
. YT-26
rice
hulls
p- toluene
sulfonic
11 Thick:
150
5
500
1.08
1322
13
130
58
YT-58-C YT-61-C
pine alder
phos- phos-
phoric phoric
150 150
3 5
500 500
1.06 1.03
2297 2148
39
252
95
YT-63-C YT-64-C OT-33
redwood ash corn cobs,
rice hulls
phos- phos- hydro-
phoric phoric chloric
150 150 150
3 35
500 500 500
1.11 1.02 0.95
3236 3188 1034
67
378
123
YT-49
wheat straw,
rice hulls
p-toluene
sulfonic
130
5
500
1.14
1965
YT-51
Cotton
Waste
phos-
phoric
150
8
500
1.09
1327
Control
ind. grade
particle
board
i
0.88
1500
56
296
127
-------
TABLE 19 (continued)
OJ
U)
Material No. YT-26 YT-58-C
Smoke number
51
315
YT-61-C
YT-63-C YT-64-C YP-33 OT-49 YT-51 Control
198
345
Water Soak 9 Days:
% weight gain
% thickness
gain
Hardness Shored
Before Test
After Test
Weatherometer (
% weight loss
% thickness
gain
Hardness Shored
Before Test
After Test
27
13
•
64
55
350 hrs.):
17
27
•
63
35
23
12
75
40
18
4
79
41
39
21
64
36
20
25
65
22
54
11
71
63
17
3
75
58
29
9
80
58
30
4
79
27
64
22
70
50
badly badly 14
weather ed weath .
warped swollen 22
fibers
exposed
70
50
* Exposed only 115 hours.
-------
II. inorganic Matrix
The studies in this task involved two types of matrix and two kinds of
composite. The two matrices considered were:
(a) an MSC inorganic matrix derived from magnesium oxychloride and
sulfates;
(b) various classes of commercial plaster.
The MSC system is the more expensive matrix, but is stronger and more
resistant to environmental effects. The plaster systems are more processable
but must be protected from moisture.
unlike the organic material, an elemental panel of an inorganic system
does not offer a product. Instead, the materials had to be directed towards
a functional application. Two applications suggested were the production of
a high density structural composite defined as a laminate, and a low density
core composite defined as a foam.
Laminate Development
Magnesium oxychloride was used in the MSC inorganic matrix. It has been
used for floor construction and interior stucco surfaces for many years and
MSC has previously studied its use as an efficient matrix.
The matrix was produced on MSC's continuous processing machinery. Glass
fibers were used as the reinforcement. The material was deposited on a tray
and allowed to "cure" at room temperature overnight. One half was covered
with an impermeable Mylar film. The panel was then removed and permitted to
continue its curing at room temperature for 28 days.
Figure 3 shows the tensile strength of the machine deposited laminate
after testing at 6, 11, 18 and 28 days. The higher values for days 6 and 11
are questionable and may be attributed to test scatter. These results show
that it is feasible to process the inorganic matrix continuously when a
faster cure is developed.
A number of waste materials were tested as reinforcers. They included
rice hulls, wood, Silvacon, paper, straw and cotton waste. The glass fibers
were so superior to the wastes in performance that other reinforcements were
disregarded. Systems, such as paper, which deteriorated when wet were com-
pletely unsatisfactory. Since the laminate is only part of the inorganic
product, a limited utilization of an inexpensive commercially available
material was considered consistent with the program study.
Studies conducted on the laminate
Figure 4 shows the effect of fiber length on strength. As can be seen,
the longer the fiber the greater the strength. Two inches is the practical
limit for processing. The superiority of a two-inch fiber is further demon-
strated in Figure 5 which evaluates the effect of fiber content. Since the
interfacial shear strength of the inorganic matrix is low compared to that of
a polyester, a longer fiber would be expected to develop greater strength.
34
-------
Figure 3 Tensile Strength of Machine Deposited Laminate
x 10'
•H
W
C
o
•rl
W
a
0)
Ul
4 -
3 -
1 .
o
deposition
plain
75"
"5T
days
-------
Figure 4
Effect of Fiber Length
500^
£ 400-
w
04
« 3°°-
•H
(0
g 200.
100.
0.
t 3 ^
8.
^7
CO
3 6-
0)
M
0)
2.
0
tension ^^/^
/ s
1 /flex
2 S PIW- Ibs/ins. width
< 1 *
1.0 2.0
Fiber Length (ins.)
xlO3
A
14-
i •>
t
9 500 .
H
J 400 .
0)
| 300 .
200 .
100
0 .
i j-*-«
10.
CO
* 8.
3
X
5 6-
4,
2_
0
J»
• / X
' A/
Y/'
A y'
/ A
20
% Fiber Content
Figure 5 Effect of Glass.Content and Fiber Length
36
-------
TABLE 20
VARIOUS PARAMETERS IN INORGANIC LAMINATE FABRICATION
Parameter
MgO
MgCL,
U)
[Glass Content = 15%]
Length Finish
Control Flex
(Psi)
Flex After 24 Hr. Soak
(Psi)
Dry
Wet
MgCl9 Source
-------
The tensile values were recorded in pounds per inch of width. Thus,
variance in thickness was not accounted for, resulting in the test scatter
shown. On an analytical basis, a higher fiber content should develop greater
strength. However, under certain processing conditions and with certain mat-
rices, a saturation point is developed where additional fibers provide limi-
ted improvement.
A number of other processing parameters were evaluated including the use
of magnesium oxide and magnesium chloride from different sources. The re-
sults are summarized in Table 20. Bare glass "AB" appears to provide the
best interfacial strength as a reinforcer.
Hie susceptibility of inorganic laminate fabrications to moisture was
also evaluated. After water immersion, the laminate deteriorated in both
strength and stiffness. In order to improve moisture resistance, a number of
organic polymers were incorporated into the laminate. Addition of polyure-
thane resulted in the greatest improvement in moisture resistance.
Tests were also performed on surface seals; alkyd paint was most effect-
ive if maintained on the surface.
The relationship of tensile stress to strain for the inorganic laminate
is shown in Figure 6. There is a clearly defined elastic region with a yield
point followed by a very long plastic region. This type of characteristic is
particularly good for building construction. If the yield point is exceeded,
there exists a very long period of deformation before failure. This period
permits corrective action to be taken before failure occurs.
In summary, these laminates demonstrate highly desirable building proper-
ties. In addition to strength, the laminate will neither burn nor smoke, it
is inexpensive and the raw materials are freely available.
Foam Development
Initial studies focussed upon development of a medium density foam for
use as a wood substitute. Desirable properties for the composite were con-
sidered to be non-flammability, lower cost than wood, and similar structural
properties. Magnesium oxychloride and casting plaster were used as the ma-
trix while the fillers and reinforcers evaluated included rice hulls, cotton
waste, scrap styrofoam, electrostatic precipitator fly ash, Silvacon 412 and
1/4" chopped glass. The electrostatic precipitator *fly ash was supplied by
the Environmental Protection Agency. Silvacon 412 is a Douglas fir bark
fiber by-product, which has an interesting needle-like crystalline form and
consists of almost equal parts of cellulose and lignin. The geometry of the
Silvacon can contribute to toughening of brittle materials. Rice hulls are a
voluminous filler with an apparent density of about 0.125 g/cm3 so that any
material containing rice hulls will have this minimum density. Any addi-
tional material that will fill voids between the hulls serves to increase the
apparent density.
38
-------
Figure g
Stress - Strain Diagram for MSC Inorganic .Matrix
vo
x!03i
5-
4.
•H ,
(A
V2
H
•H
(0
-------
Most construction systems use 2" x 4" wood profiles for door and window
framing which can warp and pose problems. A substitute for these profiles
must be light, inexpensive, non-warping and available. In order to test the
nailability of the composites formulated, two nailability tests were per-
formed: (a) the straight nail pull and (b) the bending nail pull. Composites
successful in test (a) were also evaluated under test (b).
Table 21 gives the results of these tests for the various composites for-
mulated. For all compositions, the rice hull reinforcement (dry fraction)
and the binder/filler (wet fraction) were separately premixed. Wheat straw
was evaluated as a replacement for the glass fiber reinforcement. As the
straw proportion increased, mixing became more difficult, density was reduced
by as much as 17% and nail retention reduced by up to 40%.
Hie effects on nailability of increasing the amounts of plaster and glass
fibers were also evaluated. Increasing the plaster increased the density but
had no effect on nail retention. Increased amounts of glass fibers reduced
density and increased nailability but mixing became more difficult. Dry and
wet mixing were carried out with a jiffy mixer causing no significant changes
from hand-mixed materials. To overcome mixing difficulties, 1/4" glass
fibers (with finish) were added and the density was reduced but with no in-
crease in nailability. Tables 22, 23 and 24 summarize nailability data for
various formulations.
In order to reduce process time, the effect of adding gypsum plaster to
the casting plaster was evaluated. Introduction of as much as 15 parts of
gypsum plaster caused hardening retardation of over two hours. Mixtures
containing gypsum alone showed reduced nailability and density.
The materials tested were fire resistant and low in smoke generation, and
would probably be good insulators of low density. Keeping this application
in mind, a number of binders were evaluated against the following criteria:
(a) expense;
(b) efficiency in bonding;
(c) ability to disperse or emulsify in water;
(d) ability to harden on drying.
A number of matrix binders were tested including water glass, acrylic
latex and wood bark extract. None of these binders was successful. Table 25
shows those compositions which showed structural integrity and would not
ignite under a propane torch. These binders were prepared by blending the
MSC proprietary binder with water, slowly adding the filler and blending for
an extra minute. The mix was poured on rice hulls, mixed well, placed into a
metal mesh mold and dried at 50°C or above. These compositions were sub-
jected to the NBS smoke test (see Table 26) and a modified E-84 flame spread
test (see Table 27). Both smoke density and flame spread test results showed
very good fire resistance for these compositions. As they are also inex-
pensive and light, they seem to have good potential as insulation materials.
40
-------
TABLE 21
FORMULATIONS AND NAIL RETENTION OF NAILABLE WOOD REPLACEMENTS
Mix: RH-21 RH-26 RH-27 RH-28
Component
(parts by wt.)
Rice hulls 100 50 100 100
Styrofoam (beads) 25*
1" Glass Fibers 555
(636AB)
Cotton Waste
,6. Proprietary 40 40 40 40
H binder
Vfeter 130 200 200 160
Casting Plaster 150 300
Fly ash 200 150 200
Density 0.35 0.58 0.58 0.38
Nail Retention Type 1:
Top: (Ibs.) 16.0 20.6 8.3 10.6
Bottom: (Ibs.) 20.6 19.3 14.3 15.6
Nail Retention Type 2+
Botom (Ibs.):
Side (Ibs.):
RH-29 RH-30 RH-31 RH-32 RH-33 RH-34 RH-35
100 100 100 100 100 100 90
5
5555555
10 20
40 40 40 40 40 40 40
200 200 200 200 260 260 250
300 350 300 200 200 100 300
50 100 150
0.53 0.64 0.69 0.64 0.61 0.47 0.70
8 18.6 34.6 11.3 14.6 6.6 15.0
15.6 24.0 51.0 23.6 17.6 10.6 22.6
195 225
225 190
RH-36
80
10
5
40
240
300
0.64
20.0
24.0
220
210
* for this formulation styrofoam was shredded waste beads.
+ results in type 2 test were recorded when nail started cutting along the beam, no nail was pulled out
-------
TABLE 22
NAILABLE MATERIALS CONTAINING STRAW
(Parts by Weight)
Mix:
Component
Rice hulls
Wheat straw
Binder (MSC
proprietary)
Casting
plaster
Water
Fly ash
Density
(g/cm3)
Density
(Ib./ft3)
Nail Retention*
Top
(lb.)
Average
Nail Retention
Bottom
(lb.)
Average
RH-38
75
25
40
200
150
0.42
26.3
13
9
10
10.6
23
15
11
16.3
RH-39
50
50
40
200
150
0.45
28.2
13
12
26
17
19
18
22
19.6
RH-40
25
45
40
200
150
0.42
26.6
17
19
13
16.3
24
20
40
28
RH-41
75
25
40
300
220
0.56
35.4
24
17
29
23.3
24
31
25
26.6
Rfl-42
50
50
40
300
220
0.59
36.8
24
30
32
38.6
33
25
37
31.6
RH-43
25
75
40
300
220
0.57
35.8
33
35
31
33
26
35
24
28.3
RH-44
75
25
40
150
220
150
0.49
30.9
13
14
16
14.3
21
25
22
22.6
*Type 1 test, straight nail pull
42
-------
TABLE 23
NAIIABLE MATERIALS WITH INCREASED AMOUNTS OF CASTING PIASTER AND GLASS FIBERS
(Parts by Weight)
Nix:
Component
Rice hulls
1" glass fibers
(636 AB)
RH-45
100
5
RH-46
100
5
RH-47
100
10
RH-48
100
15
1/4" glass fibers
(636 AB)
Binder (MSC
proprietary)
Casting plaster
Water
Density
(g/cm3)
Density
(Ib/ft3)
Nail Retention*
Top
(lb.)
Average
Bottom
(lb.)
Average
40
350
230
0.66
41.7
30
45
24
33
95
30
56.6
40
400
260
0.74
46.1
50
45
40
45
35
50
38.6
40
300
200
0.58
36.5
41
43
23
35.6
50
42
38.6
40
300
200
0.60
37.4
55
70
90
71.6
62
77
63
RH-49
100
5
5
40
300
200
0.61
38.3
38
30
30
32.6
31
45
35
Rl^SO
100
5
10
40
300
200
0.61
38.4
50
52
26
42.6
38
28
31
* Type 1 test: straight nail pull
43
-------
TABLE 24
NAILABLE MATERIALS CONTAINING GYPSUM PLASTER
(Parts by Weight)
Mix:
Component
Rice hulls
1" glass fibers
(636AB)
Binder (MSC
proprietary)
Gypsum plaster
Casting plaster
Water
Hardening time
Density (g/on3)
(Ib./ft3)
Nail Retention*
Top
(lb.)
Average
Bottom
(lb.)
Average
RH-51
100
15
40
300
200
hard but not
dry after 20
hr. R.T.
0.62
39.1
34
26
31
30.3
25
24
26.6
RH-52
100
15
40
150
150
200
same as
RH-51
0.71
44.5
45
69
44
52.6
73
53
55.3
RH-53
100
15
40
75
225
200
hard but
not dry
3 hr. R.T.
0.62
38.7
55
62
35
50.6
46
49
44
RH-54
100
15
40
60
240
225
hard & dry
after 2 1/4
hr. R.T.
0.65
40.9
51
26
46
41
32
48
41.6
RH-55
100
15
40
45
255
225
hard & dry
after 2 hr
10 min. at
R.T.
0.65
40.5
44
45
46
45
47
40
41
* Type 1 test: straight nail pull
44
-------
TABLE 25
COMPOSITIONS AND PROPERTIES OF RICE HULL INSULATING MATERIALS
(Parts by Weight)
Component
Composition
Rice hulls
MSC prop, binder
Fly ash
Calcium carbonate
water
Density (g/cm3)
Compressive strength (psi)
Material costs ($/ft3)
RH-8
100
40
200
150
0.31
c.a. 100
1.02
RH-12
100
40
200
150
0.37
c.a. 100
1.02
TABLE 26
NBS SMOKE DENSITY TEST RESULTS
Sample
Type of
Time to
Time to
(min)
Size of
RH-12
test: Smoldering
peak (min) 71
smoke (D-16) 1.5
sample (in.) 2.84x2.74
xl.18
RH-12
Flaming
48
2.7
2.90x2
xl
RH-8
Smoldering
89
2.0
.90 2.9x2.8
.34 xl.06
RH-8
Flaming
72
1.6
2.82x2
xl
.75
.10
Weight retention
after test (%)
57
60
45
49
47
-------
TABLE 27
FLAME SPREAD TEST RESULTS
FLAME FRONT LENGTH (in.)
Time (sec.) 1/6" Asbestos Nbm. 1 in.
20
40
60
80
100
120
140
160
180
200
220
240
260
280
300
Avg. maximum
length (in.)
Flame number t
Flame spread
ratings
Flame out time
After glow
Smoke color
Smoke quant.
Smoke odor
Tamp, of sample^
(°C)
Cement
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
5
0
0
0
0
none
none
Red Oak
10
12
13
14
14
14
16
16
19
19
19
19
19
19
19
19
14
100
2-3
4-5
white
medium
wood
not
measured
RH-8
9
9
9
9
9
9
8
8
8
7
7
7
7
7
7
9
4
28.5
0
0
white
small
wood
50°
Rh-8
9
9
9
9
9
9
8
8
8
7
7
7
7
7
7
9
4
28.5
0
0
white
small
wood
50°C
RH-12
7
7
7
7
7
7
7
7
8
8
8
8
8
8
8
8
3
21.5
0
0
white
small
wood
50°C
TH-12
7
8
9
9
9
8
8
8
8
8
8
8
7
7
7
9
4
28.5
0
0
white
small
wood
50°C
*Average maximum obtained from the three highest consecutive values recorded.
tObtained by subtracting the maximum flame length of asbestos cement from the
observed readings.
^Temperature at back of the specimens (across from burner) right after test.
46
-------
While the rice hulls were a cheap, satisfactory and plentiful filler/
reinforcement for the composite, it was decided to test a number of other
fillers. These included: magnesium chloride, magnesium oxide, calcium car-
bonate, fly ash, casting gypsum. Both fly ash and calcium carbonate seem to
be good candidates for a fire-proof filler. Casting gypsum also appears
satisfactory. Other insulating fillers tested were mineral rock wool, glass
wool, vermiculite per lite and polystyrene foam beads.
Additional binders, fire proofing agents and reinforcements were studied
as components for a fire-proof insulating material. Vinyl flat and water
glass proved to be unsatisfactory binders while the MSC proprietary binder
was most successful with a combination of rice hulls and inorganic fillers.
Glass fibers and cotton waste were both considered as reinforcement. The 1"
long glass fibers gave best results with the rice hull mixtures. Composites
containing oil starch finished fibers out-performed composites containing
silane finished fibers in strength and integrity. The cotton waste rein-
forced materials developed mold and presented mixing problems, though they
showed improved strength and nailability. None of the fire proofing agents
tested were compatible with the formulations.
In addition to the materials RH-12 and RH-8 previously discussed, three
other compositions showed promise (see Table 28). Formulation RH-31 was
developed further as a structural fire wall insulation.
A series of tests were performed on RH-31 material of thickness 0.5",
0.83" and 1.09" to determine the char depth, burn through and back tempera-
ture. Samples were placed vertically in a 4" x 4" gypsum board with a 2" x
2" hole in the center. A thermocouple was attached to the center by means of
a steel strip. A propane torch with 3/4" nozzle was directed 5" away from
the sample surface with gas pressure about 27 psi. The temperature was
adjusted to 1600°F (871°C).
It was found that the insulation effect was not linear with thickness
because the properties of the developing char were different from the non-
burned material. There was a 100°F drop in temperature at the thermocouple
placement (center of board) after the temperature peaked, attributable to the
superior insulating properties of the char. This temperature peak was not
reached by the 1" sample within a two hour period.
Weathering tests
While rice hull syntactic foams should not be exposed to outside con-
ditions or high humidity, it was decided to evaluate the effect of adverse
conditions on these materials.
The materials were soaked in water up to 7 days. Weight, compression
strength and nail pull changes were checked. Accelerated weathering up to
400 hours was also carried out. Construction of the weatherometer chamber
does not allow samples thicker than 1/2", so only weight changes could be
measured. Water soak data (Table 29) showed a higher density material which
means more plaster absorbed less water. RH-21 which included just fly ash
47
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TABLE 28
RICE HULLS SYNTACTIC FOAMS
Material No
Rice hulls
1" Glass fibers
Proprietary binder
Calcium carbonate
Fly ash
Water
Density (g/cm )
Nail withdrawal (Ibs.)
Compressive strength
(psi)
Flame spread
Smoke density
Material cost
($/ft3)
RH-8
100
40
150
0.31
0.31
100
28
72
1.02
RH-12
100
40
200
150
0.37
0.37
100
24
48
1.00
RH-21
100
5
40
200
130
0.35
0.35
350
24
48
1.02
RH-31
100
5
40
300
200
0.69
0.69
700
12
15
1.50
RH-46
100
5
40
400
260
0.74
0.74
1200
7
10
1.60
absorbed the highest amount of water.
Fly ash containing materials drastically lost their compression strength
and nail pull resistance. Plaster-containing materials lost strength and
suffered from lowered nail pull resistance but to a lesser extent. No sig-
nificant difference was noted due to increased amount-of plaster. Weather-
ometer data showed weight loss, which indicated leaching out of either fly
ash or casting plaster. After drying, the samples were firm and not warped.
It was also noted that mold growth can occur on rice hull syntactic
foams. This required a study to find proper and effective fungicides to
retard mold growth, possible under humid.or wet conditoins. The Buckman
Laboratories agreed to inoculate samples of the rice hull foams with species
of fungi in order to test the efficacy of various fungicides. The fungi
inoculated were: Penicillium roquefortii, Aspergillus niger, Chaetomium glo-
bosum and Aerobacter nerogenes. Untreated samples had a profuse growth of
48
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naturally occurring Aspergillus sp. It was found that 0.6 to 1.0 parts by
weight (with 100 parts rice hulls) of Busan 30-1 was very effective in
retarding mold growth.
TABLE 29
WATER SOAK AND ACCELERATED WEATHERING DATA
Material ——
Test FH-21 RH-31 RH-46
Water Soak:
Weight picked up (%)
2 hr. soak 49 36 29
24 hr. soak 51 37 31
168 hr. soak 52 46 36
Compressive St. (psi)
Control 350 700 1200
2 hr. soak 96 390 390
24 hr. soak 38 340 370
168 hr. soak 21 250 360
Nail pull (Ib.)
Control
2 hr. soak
24 hr. soak
168 hr. soak
18
6
4
3
43
19
27
22
45-70
16
25
30
Weatheroneter:
Weight Loss (%)
200 hr.
400 hr.
3
6
9
21
12
19
Summary
There are a variety of inorganic matrix laminates and foams of waste ma-
terials which can be used competitively in the construction industry. The
insulating material discussed above contains three major components:
(a) rice hulls as a filler/reinforcement;
(b) inorganic filler to add fire-proofing properties and act as a binder;
(c) matrix binder which may be inorganic or organic to hold the other
components together.
49
-------
Rice hulls make a good filler-reinforcement because of:
* low apparent density
* low cost
* rough surface easily bondable
* silica content lowers flammability
* abundant throughout the world.
The NSC proprietary inorganic binder was a successful matrix for
combinations of rice hulls and inorganic fillers.
50
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SECTION 5
PRODUCTS
ORGANIC MATRIX
Products which show the most promise for commercial development are:
(a) structural board
(b) replacement sheet rock
(c) lumber substitute
(d) fire doors.
(a) Structural Board
As can be seen in Table 30, organic materials show promise as a replace-
ment for commercial grade particle board. It should be noted that each com-
posite is presented in the density providing maximum strength but that dens-
ities vary in production in terms of modulus of rupture (MR). Most materials
are of acceptable strength or are superior to the commercial particle board.
The corn cob product, however, shows lower strength than the commercial
board. The higher the modulus of rupture, the more desirable the product.
The flame spread and smoke generation criteria call for lower figures to
demonstrate good qualities. As can be seen in Table 30, rice hull materials
are far superior to commercial particle board; peanut shells, are nearly as
promising as rice hulls.
Costs
Assuming that the waste material is converted into the product at the
waste material source, comparative costs for rice hull materials, peanut
shell materials, wood chips, and commercial particle board are shown in Table
31.
A complete economic analysis is given in Appendix C. Based on these
figures, retail prices for the waste material based particle board would be
58% to 84% of that of commercial particle board.
In order to reduce shipping costs for waste materials, MSC had developed
a process which reduces the bulk of the material by converting it to low
density billets. In this process, the waste is treated with acid and then
heated and dried. Through this process, shipping costs can be reduced from
$0.014/lb to $0.005/lb.
51
-------
tO
TABLE 30
SELECTED FORMULATIONS FOR ORGANIC MATERIALS
Material No.
Composite
Material
YT-26
Rice
hulls
Acid p-toluene
sulfonic
Molding 2" Thick:
Temp °C 150
Time (min) 5
Pressure (psi) 500
Density
(g/on3)
Modulus of
Rupture (psi)
Straight Nail
Pull (Ib.)
Straight Screw
Pull (Ib.)
Flame Spread
Smoke Number
1.08
1322
13
130
58
51
YT-58-C
Pine
phos-
phoric
150
3
500
1.06
2297
39
252
95
315
YT-61-C
Alder
phos-
phoric
150
5
500
1.03
2148
-
-
-
_
YT-63-C
Redwood
phos-
phoric
150
3
500
1.11
3236
-
-
-
_
YT-64-C
Ash
phos-
phoric
150
3
500
1.02
3188
67
378
123
198
YT-33
Corn cobs,
rice hulls
hydro-
chloric
150
5
500
0.95
1034
-
-
-
_
YT-126
Peanut
shells
phos-
phoric
170
15
500
1.00
2400
-
-
-
200
55 lb/ft3
commercial grade
Particle
board
-
-
—
1500
56
296
27
345
-------
TABLE 30 (continued)
U1
u>
Material No.
Composite
Material
Water Soak:
% weight gain
% thickness
gain
Hardness:
Before test
After test
YT-26 YT-58-C
Rice
hulls
27
13
64
55
Weather ometer Water (350
% weight loss
% thickness
gain
Hardness:
Before test
After test
17
27
63
35
Pine
23
13
75
40
Hrs.):
18
4
79
41
YT-61-C
Alder
39
21
64
36
20
25
65
22
YT-63-C
Redwood
54
11
71
63
17
3
75
58
YT-64-C YT-33 ST-126
Ash Corn cobs Peanut
rice hulls shells
29
9-15
80 - 80
58-60
30
4 - -
79
27
55 lb/ft3
commercial grade
Particle
board
64
22
70
50
14
22
_
50
-------
TABLE 31
COMPARATIVE COSTS OF PRODUCTS
Commercial
Rice Hulls Peanut Shells Wood Chips Particle Bd.
Material cost
Cost to mfg. (1.67)*
Cost to retailer (1.25)*
Cost at retail (1.54)*
$0.632
1.055
1.318
2.031
$0.898
1.501
1.876
2.889
$0.881
1.471
1.838
2.832
$1.133
1.797
2.246
3.459
*For the three different elements in the manufacturing series, a built-in
rule-of-thumb index was supplied by the manufacturer, i.e. for rice, the
material cost is $0.632, the manufacturer buys it for 66% greater from the
supplier (1.67 factor no.) which makes his cost $1.055 (0.632 x 0.67 $'s).
The rule-of-thumb index from manufacturer to retailer is 1.25 (25% increase
in cost); hence, cost to the retailer is $1.318 (1.055 x 1.25 $'s). The
retailer takes his profit (54%), making the ratail cost $2.031 (1.318 x 1.54
$'s).
This analysis of costs precludes consideration of labor and equipment
amortization, which are assumed to be the same regardless of the material
processed. Table 31 above indicates that waste material based panels can be
produced at 35% to 68% of the cost of commercial particle board. If the cost
of transportation within a 500 mile radius is included, then producion costs
would increase by 50 to 70% — a factor which also applies to particle board
manufacture.
(b) Sheet Rock Replacement
Sheet rock, dry wall or gypsum board are inexpensive and fire resistant,
but highly susceptible to damage from impact or water. Fire tests were per-
formed on a rice hull panel, peanut shell panel, commercial panel and sheet
rock, for period of about 20 minutes, although times varied because of diffi-
culties in controlling the fire. As a result, sheet rock was rated for 24
minutes, commercial particle board less than 20 minutes, rice hull materials
for 27 minutes, and the peanut shell panel just less than 20 minutes. The
commercial board burned most readily, and the peanut board began burning
after 15 minutes. The rice hull panel did not smoke or burn. The rice hull
panel was superior to sheet rock in performance, and was intact after the
fire. Both the rice hull panel and the peanut shell panel were superior to
the commercial particle board. It is believed that a commercial product with
comparable properties to sheet rock could be manufactured from rice hulls.
54
-------
Cost
A more complete analysis of cost may be found in Appendix C. Table 32
below compares the costs of materials made from peanut shell or rice hull
composites with the costs of manufacturing sheet rock (Board size 1/2" thick,
4' x 8').
TABLE 32
COMPARATIVE COSTS FOR SHEET ROCK SUBSTITUTES
Material Cost
Cost to Mfg. (1.67)*
Cost to Retailer (1.25)*
Cost at retail (1.54)*
Rice Hulls
$0.519
0.867
1.083
1.668
Peanut Shells
$0.737
1.231
1.538
2.369
Sheet Rock
$0.508
0.848
1.060
1.632
* See explanation below Table 31.
Rice hull sheets could be cost-competitive with sheet rock but peanut
shell composites are more expensive. If, however, board of equivalent
strength made from the three materials are compared rather than boards of the
same size, then the rice hull panel appears even more economically com-
petitive with the sheet rock. In order to make the comparisons below, the
rice hull panel weight of 73 Ib/cu ft. was compared to the 80 lb/ cu ft. of
sheet rock and 58 Ib/cu ft. of peanut shell panels.
Rice Hulls (1/2") Peanut Shells (3/8") Sheet Rock (1/2")
Material Cost $0.519 $0.583 $0.508
Cost to mfg. (1.67)* 0.867 0.973 0.848
Cost to Retailer (1.25)* 1.083 1.217 1.060
Cost at Retail (1.54)* 1.668 1.874 1.632
*See explanation below Table 31.
55
-------
Screw and nail retention qualities of the organic panels are equivalent
to sheet rock. The rice hull and peanut shell panels are more durable, more
crack resistant and easier to work than the sheet rock. The greater flame
resistance of the rice hull panels may give them a competitive edge over the
slightly cheaper sheet rock panels.
(c) Lumber substitute
A third area in which the waste material panels may be competitive is as
a substitute for lumber. Four qualities are important in this respect:
* equivalent strength
* equivalent nail and screw retention
* dimensional stability
* workability with carpenter type tools
Lumber substitutes are already being marketed at costs which are not
particularly competitive with ordinary lumber. These substitutes have ad-
vantages in utilization of waste materials and in dimensional stability.
Tests with straight nail pull and straight screw pull indicated that the
rice hull panel was inferior to the commercial panel and far below that of
wood chip panels. All organic waste panels were easily workable with con-
ventional carpentry tools.
In terms of costs, material for the 2" x 4" organic panel would be $0.037
per foot, retailing for $0.120 per foot — compared to costs of conventional
materials of $0.15, retailing for $0.20 per foot.
Despite cost advantages, more engineering development is required before
the material can be considered as a lumber replacement. By redesigning the
hardware of the plant, it should be possible to upgrade the panels to the
quality of pine lumber or Douglas fir. This would require rethinking the
design of performer, dryer, loading hoist, press and unloading hoist for a
continuous feed process. Using 1967 cost figures, it is possible to estimate
that the plant cost in 1975 dollars would be in the region of $4.5 million
(see Appendix C).
The economic figures contained in Appendix C are based on production
equipment not yet designed. In spite of assumptions it does appear that some
product potential is indicated.
jd)_ __Fir_e doors
Building standards require fire doors which will resist fire in excess of
one hour. Based on an extrapolation from the previously reported data on
1/2" thick panels, blanks of 1 1/2" thick peanut shells, rice hulls or wood
chips would withstand fire for two to three hours. A blank of any of the
organic materials could be machined by routine door equipment, and hardware
could be installed directly into the blank.
56
-------
Cost
Assume a door requires 150 pounds of raw material: thus the material cost
for a door is $1.67.
Assume present core sales to retailer of $12 per door giving a cost
differential of $10.33.
Assume operational costs of $8,326 per day.
Breakeven production rate is then:
8 326
Doors per day = ' „ = 806 doors.
TO3
Assume a production rate of 2500 doors/day:
Generated Sales = $25,825
Operation cost = 8,326
Profit $17,499/day
This would generate yearly sales of $4,549,740. It is concluded there-
fore, that if a sufficient market is available for fire doors, that the or-
ganic panels would make an excellent product for commercial development.
(These figures were based on the manufacturers own data and must be presumed
to be based on reasonably accurate assumptions. There is no way to verify.)
From concept to market — cqstsjjf^ product development
To this point there has been focus on the cost competitiveness of the
four products discussed above. All are derived from waste materials and show
varying degrees of potential at the market place.
For each of these four products, a further economic analysis has been
performed to determine the cost of getting the product to the market place.
Four basic steps are involved for each material:
(1) design and qualification;
(2) development of manufacturing procedures;
(3) application of product to the market;
(4) acceptance of the product.
Table 33 below provides comparative figures for design and qualification
costs for three separate products (panels, lumber substitute, and fire
doors). Costs for the second product (lumber) are higher, due to the need
for changing the production process from that used for similar products
presently manufactured. Panels require the least change from present pro-
cedures, and this is reflected in the lower costs.
Table 34 below shows the comparative costs of development and manufactur-
ing. Again the high cost of product development for the lumber substitute is
clearly evidenced in comparison with the other two products.
Analysis of the practicality of developing the products entails consider-
ation of physical properties of the material and its potential as a competi-
57
-------
TABLE 33
DESIGN AND QUALIFICATION COSTS
REQUIRED TEST RECOMMENDED TESTS
01 rH
0) jQ
•2S g ti S
> TD "'"I O 4J O El
CD 9 13 (d Jj QJ O «.^ u rfl
cojacogsvi -H co5^oo o
r-jOdJcym.H CD wco ^u-i o
s ^s. su H, s .s a 3 i « » -H^ «
"T2y-dirlw ^Jri K«0 -f 5T *• ti S IH
' =? «H S $ -. 3i 2--I CCirH «j Q,g n
^^ SS1 1 Jl 5 *6 y « '3 e- v
•H > -a 4J O J3
.HVJhJjftcH £^JBartJ u S IH 2 to =Jfl3 8
ZftEHfaH WS Ok
Panel $2,800 $1,000 $500 $300 $400 $200 $50 $50 $1,000 $570 $1,000 $7,780 (1.76) = $113,851
Product
Lumber 16,800 1,000 500 300 400 500 5,000 5,000 570 1,000 31,070 (1.76) = 54,683
Substi-
tute
Fire 10,080 2,500 200 500 3,000 579 1,000 17,750 (1.76) = 31,240
Door
Material
-------
TABLE 34
DEVELOPMENT AND MANUFACTURING
Process technical services
civil codes burden
Laboratory equipment
Material cost
Scale up technical services
civil codes burden
Studies: process line purchase
Material costs
Pilot run technical services
(includes burden)
Studies: additional line purchases
Process line operation
Material costs
Start up product technical
services includes burden
Need: Additional equipment
Process line cost*
Material cost*
Cost
Multiplier (for normal
problems)
Probable cost
Particle
Board
$
-
-
-
6,720
12,000
-
13,440
60,000
(1500/hr)
800
10,080
180,000
(1500/hr)
2,400
285,480
(2.09)
596,674
Lumber
Substitute
$
43,680
50,000
500
43,680
475,000
1,000
43,680
370,000
60,000
(1000/hr)
5,000
43,680
1,660,000
80,000
(1000/hr)
23,827
3,000,047
(2.09)
6,270,098
Fire Door
Material
$
—
-
-
6,720
12,000
-
6,720
36,000
500
6,720
30,000
3,365
102,075
(2.09)
213,336
59
-------
TABLE 35
Composition
I. Rice hulls (100 parts)
1" long fiberglass
strands (15 parts) MSC
proprietary binder (40
parts) casting plaster
(240 parts) gypsum
plaster (60 parts)
water (225 parts)
vancide PA germicide
(.5 parts)
II. Glass and plaster rice
hull foam (.129 ft3)
inorganic glass pan
(2.79 ft2) adhesive
(.079 Ibs)
III. Rice hulls (30 parts)
casting plaster (90
parts) MSC proprietary
binder (12 parts) water
(66 parts) Busan (30
parts)
IV. Glass and plaster rice
hull foam (.174 ft3)
inorganic glass pan
(2.79 ft2)
adhesive (.0791 Ibs)
V. Rice hulls (100 parts)
MSC proprietary binder
(40 parts) Fly ash (200
parts) water (150
parts) Glass and gypsum
PRODUCTS AND COMPOSITION
Use
Wood substitute
Fire rated partition
wall:
(a) Interior wall
panels
(b) Floor panels
(c) Ceiling systems
(d) Roof systems
Fire door core
Waste floor/ceiling
Ceiling panels
Material or Product Cost
.10/ftr retailing at $.32
commercial price is about
1/2 the price (lumber)
$.875/ft commercial
two-hour fire rated
wall: $1.79/ft2
$1.791/ftJ
waste core: $8.71
commercial core: $12.00
$1.061/ft commercial
wood product: 1.624/ft2
commercial concrete
product: $1.696/ft2
sale price: 80.15 to
$0.39/ft2
commercial: $0.455 to
$9.00/ft2
60
-------
tive product. This requires a market for the material and acceptance by
potential users. Tasks involved in market development include the selection
of a market and choice of methods of market penetration followed by actual
marketing.
For the organic waste panels as a substitute for standard panels, mar-
keting could be accomplished for a cost of $50,000 to $60,000. This product
has a readily available market, and product acceptance should be easily
accomplished. Competitive pricing would be the main impetus for purchase.
The organic waste panel substitutes for sheet rock board will be more
difficult to market due to higher price when compared with sheet rock. Market
acceptance in this case must rest on superior performance. Marketing costs
are estimated at $250,000.
Lumber substitutes will require proof of qualities comparable to lumber.
marketing should be through an existing distribution system, at a cost
estimated at $125, 000. Acceptance of this product will come through time.
A subsidy is suggested as a means to encourage potential users to try the
material. An estimate of a reasonable subsidy is $250,000. Thus to market
thisproduct, it may be necessry to invest $3.4 to $6.7 million. This sum
could be recovered in one year if the market could sustain a 500,000 board
feet per day production which is unlikely.
Fire doors will find ready acceptance in the market, since they would
meet code approval at a very competitive price. They could be distributed
through an existing wood products distribution. The marketing cost is
estimated at $50,000. Product acceptance can be assured by insuring that the
product is the same as present products. Thus, to achieve a market, a cost
of $169,825 to $294,576 is estimated, which could be recovered after one year
of production.
INORGANIC MATERIALS
Five composites were evaluated as potential products. As with the
organic products previously discussed, economic viability of the product in a
competitive market as well as mechanical acceptability were considered. The
five composites and product uses considered in this report are presented
below.
(a) Lumber substitute for framing material
After a series of tests involving the evaluation of a 51" wide window
panel and a 73" wide sliding glass door panel against building code stand-
ards, the wood substitute material was found to be below ICBO standards.
Moreover, as can be seen from Table 35 above, products made from this mater-
ial would not be cost competitive with lumber. Therefore, although the ma-
terial is lightweight, nailable, and fire resistant, it was dropped from
further consideration.
61
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(b) Fir^ rated partition wall
Fire tests indicated a need for an all inorganic composite when the poly-
ester inner skin of the tested wall material was found to soften and burn at
high temperatures. Hie waste composite was compared to commercial products
on flexure and load tests. The panel tested performed much better than the
previously qualified panels to which it was compared on stiffness. Costs of
installation of the test panel were only 49% of conventional panels. Costs
could further be reduced by lowering quality of the product or possibly by
constructing the panel in one piece.
Fire tests showed that the panel was able to withstand flame for 3 hours
with no smoke generation. As can be noted from Table 35, the partition wall
is cost-competitive with commercial fire walls rated for two hour resistance.
Fire smoke tests indicated superior qualities for the waste panel compared
with the commercial product.
The same composite used in the fire rated partition wall could also be
used for interior wall panels, floor systems, ceiling systems, roof systems
and floor ceiling paneling. Interior wall panels could be produced for 76%
of the cost of a standard 2" x 4" stud dry wall construction and would be a
variation on the fire-rated partition wall.
Floor systems could be produced using the fire-rated panel finished with
an attractive hard-wearing ceramic surface. The cost would be 74% of the
cost for concrete slab and 53% of the cost of standard wood construction.
Self-supporting ceiling panels could be finished with a textured surface.
The cost would be 69% of standard dry wall ceiling construction. The roof
panel would require an impermeable seal as for any standard roof. The cost
is 69% of standard wood construction.
All of these products would be fire-resistant and non-smoke generating.
All could be prefabricated. Performance standards to be met are less strin-
gent than for fire doors.
(c) Floor/ceiling system
A fire-resistant, non-smoking floor/ceiling panel was tested and found to
be much stiffer than required for floor panels under current building codes.
The floor/ceiling panels would be interlocking with end attachments designed
for standard roofings or floor beam construction. Joints on both sides could
be filled with an inorganic matrix of compatible texture. This system would
cost 62% of the cost of standard wood construction and 59% of the concrete
slab system. Moreover, the panel could be designed to fit over standard 2" x
4" sill plates; it is light (less than 200 pounds, allowing ease in handling)
and the material can be easily cut with a standard carbide power saw. Like
the other products made from this material, the panels can be prefinished at
the factory. As can be seen in Table 35, the panels are cost competitive
with the standard product.
62
-------
The ceiling panel market is very competitive. The waste ceiling panels
performed better on flame tests than the conntercial product but their cost
would be in the upper cost range for similar products already on the market.
Therefore, it was not considered profitable to pursue this product further.
(d) Fire door core panels
Core panels or inorganic matrix/rice hull reinforcement 1 1/2" thick were
faced with standard wood veneer surfaces and fire tested using standard tech-
niques. Standard doors with cores of 2.33 ft3 could be formed and sold at
a price competitive with the current price. The cost was $8.71 for the waste
core products, one with a thin inorganic glass facing under the veneer, and
another covered only with veneer. Fire ratings were far superior to the
standard commercial door (fire test times were 140 minutes, 130 minutes, and
78 minutes, respectively).
Costs
Design and qualification costs
Table 36 below shows the estimated costs for product design and for gain-
ing qualification under existing building standards. Only three of the five
main products were rated since the ceiling panel and the wood substitute did
not show promise as marketable products.
Development and manufacturing procedures-costs
Table 37 gives the costs for the fire wall and the fire door core panels.
The fire wall panels could be manufactured using standard concrete manufact-
uring equipment with some modification (not yet determined). Cost range is
estimated from $79,600 to $144,076 depending on size of plant.
The fire door core could be manufactured using a modified plaster mixer
with a continuous feed onto a conveyor of molds. Costs of the development of
the manufacturing procedure is estimated to range from $82,753 to $49,782.
Marketing
Getting the product to the market involves selection of a market, evalu-
ation of methods for market penetration, selection of a method of marketing,
and actual marketing activities. The fire wall panel could probably be in-
corporated into the existing distribution system for such products. This
procedure would cost an estimated $75,000. Gaining acceptance for the prod-
uct should proceed through building contractors. A subsidy to encourage in-
itial use is recommended at an estimated $250,000.
Marketing and product acceptance for the fire door cores is estimated at
$28,160. A first step in design and qualification would be selection of an
interested fire door manufacturer to construct a door with the core, which
could then be qualified under building code requirements. Thus the remaining
cost of marketing and gaining product acceptance is comparatively small. The
cost of marketing the floor/ceiling panels would be similar to the costs for
63
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TABLE 36
DESIGN AND QUALIFICATION COSTS INORGANIC PRODUCTS
Fire Fire door Floor/ceiling
wall core system
Technical services $ 3,360 $ 3,360 $ 3,360
(includes burden)
Mechanical test 5,000 3,000
Fire Door Test
Standard fire test 2,500 4,000 5,000
Standard tunnel test 800 " 5,000
(smoke and flame)
Materials 200 50 200
Tooling 1,000 100 1,000
Filing fees 570 570 570
Travel and support 1,000 1,000 1,000
Estimated cost 4,430 9,080 14,930
Multiplier (to ac- (1.76) (1.76) (1.76)
count for normal
problems [1.76])
Probable cost $ 25,397 15,981 26,277
64
-------
TABLE 37
DEVELOPMENT AND MANUFACTURING PROCEDURES - COSTS INORGANIC PRODUCTS
Fire
Wall
Fire door
core
Scale up studies;
Technical services
(includes burden)
Equipment costs
Material cost
Pilot Run;
Technical services
(includes burden)
Equipment cost
Material cost
Start up and adjust-
ment to product needs;
Technical services
(includes burden)
Equipment cost
Material cost
Estimated cost;
Multiplier (to ac-
count for normal
problems [1.81])
Probable Cost:
$ 6,720
6,000
1,000
6,720
6,000
(150/hr)
3,000
13,440
6,000
(150/hr)
30,720
79,600
(1.81)
$ 144,076
20,160
1,384
($4/hr)
1,086
20,160
1,038
($4/hr)
38,925
60,123
(1.81)
$ 149,782
65
-------
the fire wall panels, i.e. an estimated $325,000.
Total costs
Taking into account the costs of design and qualification, development of
manufacturing procedures, and marketing and gaining product acceptance, total
costs for getting the products discussed above to market are:
Fire wall panel - A cost of from $419,030 to $494,473
Fire door core - A cost of from $129,993 to $203,923.
If the $12 sales price is maintained and the waste core cost is $8.71, a
profit of $493,500 over costs can be extrapolated after the first year, as^
suming sales of 150,000 cores. For the floor/ceiling system a cost from
$149,530 to $493,353 os estimated to get this product to market.
Summary
It is clear from the above discussion of products and costs that market-
able building materials could be manufactured using waste materials. Satis-
factory products could be made using both inorganic and organic systems. Of-
ten structural properties of the formulations were superior to existing com-
mercial products. The economic analyses so far performed indicate that sev-
eral products would be competitive at the market place - notably fire-retard-
ant materials containing rice hulls (as either matrix or reinforcement).
66
-------
BIBLIOGRAPHY
(a) Fillers
Abrahams, J.H. Jr. Recycling Container Glass. Proceedings of the Third
Mineral Waste Symposium, 1974.
Anon. Refuse Glass Aggregate in Portland Cement Concrete Waste Glass as an
Ingredient in Lightweight Concrete. Proceedings of the Third Mineral
Waste Conference, 1974.
Anon. Solid Waste as Fuel for Power Plants. Horner and Shifrin Inc. PB
220-316.
Anon. Utilization of Mining and Mill Wastes. Bureau of Mines — Contract
No. H0190397 - IITRI Project No. G6027
Anon. Utilization of Phosphate Slimes. International Minerals & Chemical
Corp., EPA Project 14050 EPV
Covey, J.N. and J.H. Farber. Ash Utilization — Views on a Growth Industry.
Proceedings of the Third Mineral Waste'Symposium, 1974.
Cox, J.L. Phosphate Wastes. International Minerals and Chemical
Corporation, First Mineral Waste Utilization Symposium, 1972.
Dean, K.C., C.J. Chindgren and L. Peterson. Recovery of Values from Shredded
Urban Refuse. Proceedings of the Third Mineral Waste Symposium, 1974.
Davis, R.L., P.G. Hansen and S.C. Kekar. Extrusion — A Means of Recycling
Waste Plastic and Glass.
Faber, J.H.. Fly Ash Utilization — Problem and Prospects. Bureau of Mines,
First Mineral Waste Utilization Symposium, 1972.
Gouivens, P.R. Utilization of Foundry Waste By-Products. First Mineral
Waste Utilization Symposium, 1972.
Grubbs, M.R. and K.H. Luey. Recovering Plastics from Urban Refuse by
Electrodynamics Techniques. College Park Metallurgy, College Park
Maryland; Research Center, Bureau of Mines, Solid Waste Research Program
TPR 63, December 1972.
67
-------
Hansen, P.G. and R.L. Davis. Utilization of High-Pressure Forming for
Converting Waste Glass into Useable Structural Materials. Dept. of
Mechanical Engineering, University of Missouri, Rolla-Contract GO 100158
(SWD-27) U.S. Bureau of Mines.
Hecht, N.L. Application of Silicate Waste from Paper Processing. Proceedings
of the Third Mineral Waste Symposium, 1974.
Hough, J.H. and H.T. Barr. Possible Uses for Waste Rice Hulls in Building
Materials and Other Products. Bulletin No., 507-Agricultural Experiment
Station - Louisiana State University and A & M cCollege.
Pincus, A.G. Wastes from Processing of Aluminum Ores. IITRI, First Mineral
Waste Utilization Symposium, 1972.
Shotts, R.O. and R.M. Cox. Feasibility of Utilizing Waste Glass as a
Component for Lightweight Structural Building Products. U.S. Bureau of
Mines Contract G0100S9 (SWD-28) College of Engineering, University of
Alabama BER Report 140-119.
Sullivan, G.D. Coal Wastes. American Mining Congress, First Mineral Waste
Utilization Symposium, 1972.
Sullivan, P.M. and M.H. Stanczyk. Economics of Recycling Metals and Minerals
from Urban Refuse. Bureau of Mines Solid Waste Research Program, Tech
Progress Report 33, April 1971.
Vasan, S. Utilization of Florida Phosphate Slimes. Proceedings of Third
Mineral Waste Conference, 1974.
(b) Reinforcements
Anderson, A.B., A. Wong and K. Wu. Utilization of White Fir Bark in Particle
Board. Forest Products Journal 24(1).
Anon. Cultural and Harvesting Methods for Kenaf Production. Research Report
No. 113, Dept. of Agriculture.
Anon. How Sewage & Solid Wastes Can Be Recycled into Useful Products.
Research Trends, pp. 54-58, Autumn 1971.
Barbour, J.F. and R.R. Grover. The Chemical Conversion of Solid Waste to
Useful Products. Dept. of Agricultural Chemistry - Oregon State
University.
Chow. P. New Uses Found for Discarded Christmas Trees. Illinois Research
15(3), Summer 1973.
Chow, P., C.S. Walters and J.K. Guiher. Ph Measurement for Pressure-Refined
Plant-Fiber Residues.
68
-------
Clark, T.F. et al. A Search for New Fiber Crops. The Journal of Technical
Association of the Pulp and Paper Industry 50(11), November, 1967.
Cox, F.B. and H.G. Geyrayer. Expedient Reinforcement for Concrete for Use in
Southeast Asia. Tech. Report C-69-3CL. Corp of Engineers, Vicksburg,
Mississippi.
Cox, F.B. and J.E. McDonald. Expedient Reinforcement for Concrete for Use in
Southeast Asia. Tech Report C-69-3 #3 - Corps of Engineers, Vicksburg,
Mississippi.
Cservenyak, F.J. and C.B. Kenahan. Bureau of Mines Research and
Accomplishments in Utilization of Solid Waste. I.C. 8460.
Currier, R.A. An Assessment of Current Bark Utilization Opportunities.
Dept. of Forest Products, Oregon State Univ.
Currier, R.A. and W.F. Lehmann. Bark as an Ingredient in Molded Items,
Particle Boards, Adhesive and Other Products. Dept. of Forest Products,
Oregon State University.
Fan, L.T., D.G. Retsloff and W.O. Vanderpool. Solid Waste-Plastic
Composites: Physical Properties and Feasibility for Production.
Environmental Science & Technology, 6(13)1085-1091, Dec. 1972.
Gloria, H.F. Bagasse Structural Board-Our Hope? Central Azucarera de Bair,
Sugarland, June-July, 1972.
Grover, R.R. and J.F. Barbour. Industrial'Utilization of Solid Waste -
Economic and Engineering Analysis of a Straw-Particle Bord Plant. Dept.
of Agricultural Chemistry, Oregon State University.
Chow, P. C.S. Walters and J.K. Guiher. Specific Gravity, Bulk Density and
Screen Analysis of Midwestern Plant Fiber Residues. Forest Products
Journal 23(2).
Henn, J.J. and F.A. Peters. Cost Evaluation of a Metal and Mineral Recovery
Process for Treating Municipal Incinerator Residues. I.C. 8533-Dept. of
Interior.
Hough, J.H. and H.T. Barr. Possible Uses for Waste Rice Hulls in Building
Materials and Other Products. Bulletin No. 507 Agricultural Experiment
Station, Louisiana State University and A & M College.
Kenahan, C.B. and E.P. Flint* Bureau of Mines Research Programs on Recycling
and Disposal of Mineral, and Energy Based Solid Waste. I.C. 8529, Dept.
of Interior.
Kenahan, C.B. and R.S. Kaplan. Bureau of Mines Research Programs on
Recycling and Disposal of Mineral, Metal, and Energy Based Wastes. I.C.
8595, Dept. of Interior.
69
-------
Lockhart, R.J. and S.A. Bartz. Development of Cabron Products from Lignin
(Paper Mill) Wastes. Proceedings of the Third Mineral Waste Symposium,
1974.
Miller, D.J. Molding Characteristics of Some Mixtures of Douglas-Fir Bark
and Phenolic Resin. Forest Products Journal 22(9).
Sullivan, P.M., M.H. Stranczyk and M.J. Spendlove. Resource Recovery from
Raw Urban Refuse. R.I. 7760- Dept. of Interior.
Van Vliet, A.C. Converting Bark into Opportunities. Oregon State University,
Dept., of Forest Products.
Walters, C.S. Utilization of Plant-fiber Residues. University of Illinois,
College of Agriculture.
(c) Matrices
Anon. Industrially Significnt Organic Chemicals, Part 7: Lignin Sulfonic
Acids (Na and K Salts) Chemical Engineering, June 24, 1974.
Harbour, J.F. and R.R. Grover. The Chemical Conversion of Solid Waste to
Useful Products. Dept. of Agricultural Chemistry, Oregon State
University.
Hough, J.H. and H.T. Barr. Possible Uses for Waste Rice Hulls in Building
Materials and Other Products. Bulletin No. 507 Agricultural Experiment
Station, Louisiana State University and A & M College.
Nee, C.I. and W.C. Hsich. Furfural From Bagasse. Int. Soc. Sugar Cane Tech.
Proc. 13th Cong. pp. 1881-1890, 1970.
Parker, H.W. fuels and Petrochemicals from Agricultural Waste. 76th
National AICHE Meeting, March 1974.
Weakley, F.B. Protein Glue - USDA, Peoria, Illinois.
Weakley, F.B. and W.B. Roth. Mill Evaluation of Dialdehyde. Starch-Protein
Glue for Hardwood Plywood Manufacture. Forest Products Journal 23(7),
July, 1973.
Wellons, J.P. and R.L. Krohmer. Self Bonding in Bark Composites. Wood
Science 6(2), October 1973.
70
-------
APPENDIX A
RATING SYSTEM CRITERIA
A. Matrix Candidates
1. Curability: Ambient temperature to 150° F
151° F to 250° F
251° F to 350° F
351° F to 450° F
451° F and up
Noncurability
2. Absence of Arcma:
No odor in precursor compound or final form
Mild odor in precursor compound and none
in final form
3. Processability
a. Time:
b. Pressure:
Requires 2 to 10 minutes
Requires 10 to 12 minutes
Requires 12 to 14 minutes
Requires 15 to 60 minutes
Requires less than 2 minutes, more than
60 minutes
Roller, 0 to 15 psi
16 to 25 psi
26 to 50 psi
51 to 100 psi
Greater than 100 psi
c. Temperature: Ambient to 150° F
151° F to 250° F
251° F to 350° F
351° F to 450° F
450° F and up
4. Physical Form:
Liquid
Soluble solid
Insoluble solid but fusible below 350°
Insoluble solid but fusible below 500°
Inprocessable by our standards
5 pts
4 pts
3 pts
2 pts
1 pt
0
5 pts
4 pts
5 pts
4 pts
3 pts
2 pts
1 pt
5 pts
4 pts
3 pts
2 pts
1 pt
5 pts
4 pts
3 pts
2 pts
1 pt
5 pts
4 pts
3 pts
1 pt
0
71
-------
S.Toxicity:
Ndntoxic 5 pts
Noxious 3 pts
Toxic 0
6. Decomposability:
7. Color:
8. Availability:
Undecomposed to 600° F 5 pts
Undecomposed to 500° F 4 pts
Undecomposed to 500° F 3 pts
Undecomposed to 400° F 2 pts
Undecomposed below 400° F 1 pt
Absence of Color 3 pts
Light Color 2 pts
Dark Color 1 pt
Black 0
Available in useable state 10 pts
Useable but in short supply 4 pts
Raw material broadly available,
collectable, process known 8 pts
Raw material broadly available,
collectable, process to be developed 7 pts
Raw material broadly available,
collection problems, process known 6 pts
Raw material availability localized,
collectable, process known 3 pts
Raw laterial availability localized,
collection problems, process known 1 pt
Raw material availability localized,
collection problems, to be developed. 0
B. Reinforcement Candidates
1. Mechanical properties
a. Tensile strength 100 psi and greater
50 psi to 99 psi
less than 50 psi
b. Modulus: 2,000,000 psi and greater
1,000,000 psi to 1,999,999 psi
500,000 psi to 999,999 psi
Less than 500,000 psi
2. Surface to volume ratio: High
Medium
Low
3. Length to Width Ratio:
High
Medium
Low
5 pts
4 pts
1 pt
5 pts
4 pts
3 pts
1 pt
5 pts
3 pts
1 Pt
5 pts
4 pts
2 pts
72
-------
4. Absence of Aroma:
5. Availability:
None 5 pts
Mild 2 pts
Strong 1 pt
Stench 0
Available in useable state 10 pts
Useable but in short supply 4 pts
Raw material broadly available,
collectable, process known 8 pts
Raw material broadly available,
collectable, process to be developed 7 pts
Raw material broadly available,
collection problems, process known 6 pts
Raw material broadly available,
collection problems to be developed 5 pts
Raw material availability localized,
collectable, process known 3 pts
Raw material availability localized,
collectable, process to be developed 2 pts
Raw material availability localized,
collection problems, process known 1 pt
Raw material availability localized,
collection problems, process to be
developed 0
C. Filler Candidates
1. Reactive to Matrix Material (In Destructive Sense)
Inert
Very slow (requires at least 20 yrs)
Slow (requires at least 15 years)
Medium (requires at least 10 years)
Rapid (requires at least 5 years)
2. Decomposability:
3. Grindability:
4. Density:
Undecomposed to above 2000° F
Undecomposed below 2000° F
Undecomposed below 1500° F
Undecomposed below 1000° F
Undecomposed below 750° F
300 mesh or better
200 to 300 mesh
100 to 300 mesh
50 to 100 mesh
less than 50 mesh
Point value = 5 specific gravity
5 pts
4 pts
3 pts
2 pts
1 pt
5 pts
4 pts
3 pts
2 pts
1 Pt
5 pts
4 pts
4 pts
2 pts
1 pt
73
-------
5. Absence of Aroma: None 5 pts
Mild 2 pts
Strong 1 pt
Stench 0
6. Availability: Available in useable state 10 pts
Useable but in short supply 4 pts
Raw material broadly available,
collectable, process known 8 pts
Raw material broadly available,
collectable, process to be developed 7 pts
Raw material broadly available,
collection problems, process known 6 pts
Raw material broadly available,
collection problems to be developed 5 pts
Raw material availability localized,
collectable, process known 3 pts
Raw material availability localized,
collectable, process to be developed 2 pts
Raw material availability localized,
collection problems, process known 1 pt
Raw material availability localized,
collection problems, to be developed 0
74
-------
APPENDIX B
KEY TO ORGANIC MATRIX SECTION
hydrolysis, hot HC1
(c IT n 1
4 8 4 n +
a 4 n H20f H +
pentosan
(from oat hulls,
corn cobs, rice
hulls)
H
1
C = 0
1
H-C — OH
...» |
H-C— OH
1
H-C— OH
1
H-C— OH
1
H
pentose
pentose
dehydrated
& cyclized
furfural
CHO
1
1
CH-OH
~3H2°
ring closure
C — C
> l/™\ !
\/c
—c=o
furfural
(2-furancarboxyaldehyde)
75
-------
Phenol-Aldehyde Resin Reaction (Using Furfural)
0>
HO
.o
phenol
or OH~
polymerization
C — OH
_OJ i ...CD
o-hydroxyl furfural
phenol
dehydrate
OH
C-H20)
HO
OH
...C2)
OH
O
0 CHO
(3)
76
-------
Equation 1: The phenol reacts with the furfural to form an ortho or para
hydroxyl furfural phenol.
Equation 2; The hydroxyl furfural phenol then reacts wtih another molecule
of phenol, resulting in the loss of one molecule of water to form a compound
in which the two rings are joined by a (^\ link.
I
H
Equation 3; This process continues to yield a product of high molecular
weight.Since three positions of each phenol molecule are susceptible to
attack (namely the 2, 4 and 6 carbons or the two ortho and the one para
positions,) the final product contains numerous cross-links and hence has a
rigid structure.
77
-------
APPENDIX C
COST ANALYSES FOR COMMERCIAL PLANTS
I. Organic Matrix - Structural board
Assume, plant cost of $8.27 million for production of 200 tons/day or 55
million sq. ft. of 1/2 inch board per annum at 45 Ib/cubic foot density.
Assume material cost of $0.997/lb for rice hulls, $0.011/lb for peanut
shells, $0.10/lb for wood chips.
Assume retail price of $0.031/lb, using commercial figures for particle
board at 55 Ib/cubic foot.
Assume fixed operation costs for plant capacity of:
Labor ............................... $374,000/annum
Other direct costs .................. 292 ,600/annum (not including
material)
Indirect costs ...................... 283,800/annum
Deprecistion of 10% ................. 8 27, OOP/annum
Total costs/annum $ 1,777,400
Costs/day 6,836
Break even production rate would be:
For rice hulls: = 6,836/day 67 lb/ft^ Rice hulls
346,978 Ibs/day. .024/lb 55 lb/ft* Conmercial
For peanut shells:
cost retail diff = *'**%& x 62 Ib/ft* Rice hulls
385,302 Ibs/day. -020/lb 55 Ib/ft^ Commercial
For wood chips:
cost retail diff = *&?)(& x ™ ff/g *ce ""Pf =
372,873 Ibs/day. .021/lb 55 Ib/ft3 Commercial
Assume full production. Facility costs are based on 200 tons/day of 45
Ib/ft3. The plant production is limited by volume, not density, i.e., more
dense panels of 60 Ib/ft3 would mean production of 267 tons/day.
78
-------
Profits would be as follows:
Rice hulls: 534,000 (.024) (55/67) = $10,520/day sales
- 6,836/day cost
$3,684 (260 days)
3,684/day profit or
= $ 957,840/annum
Peanut shells: 534,000 (.020) (55/62) = $ 9,474/day sales
- 6,836/day cost
$2,638 (260 days)
2,638/day profit or
= $ 685,880/annum
Wood shavings: 534,000 (.021) (55/63) = $ 9,790/day sales
- 6,836/day cost
$2,954 (260 days)
2,054/day profit or
$ 768,040/annun
Table 38 below gives the costs for commercial plants in comparison with
rice hulls or peanut shell plants, using figures for 1967 and converting to
particle board plant costs for 1975.
Estimated particle board plant cost in 1975 is $3.2 million plus $135,000
per million square feet of annual production. Therefore for a 200 ton per
day plant (55 million sq. ft. annual production), the cost would be $3.2
million plus 55 times $135,000 or $10.6 million.
TABLE 38
COMPARISON OF CONVENTIONAL WOOD SHAVINGS PLANT
WITH A RICE HULL OR PEANUT SHELL PLANT
Conventional Wood Shaving Plant
Unloading & storage $ 120,000
Milling & drying 190,000
Bending & forming 490,000
Press line 1,020,000
Finishing section 350,000
Auxiliary equipment 270,000
Total equipment cost 2,440,000
Rice Hull or Peanut Shell Plant
Unloading & storage
Acid wash
Forming & drying
Press line
Finishing section
Auxiliary equipment
$ 120,000
100,000
150,000
1,020,000
350,000
175,000
Total equipment cost 1,915,000
79
-------
Production for Five Year Pay-Off
Cost per day (8.27 x 106)/5 x 260) + 6,836 = $13,198/day
Production required for:
Rice hulls: 13,198/.024 (62/55) = 669,898 Ibs/day
= 355 tons/day
7,499 panels 1/2" x 4' x 8'/day
= 62 MM sq. ft. of 1/2' board/year
Peanut shells: 13,198/.020(62/55)= 734,869 Ibs/day
= 367 tons/day
8,891 panels 1/2" x 4' x 8'/day
= 74 MM sq. ft. of 1/2" board/year
Wood shavings: 13,198/.021(63/55)= 719,890 Ibs/day
= 360 tons/day
8,572 panels 1/2" x 4' x 8'/day
= 71 MM sq. ft. of 1/2" board/year
Conclusions
The developed waste process is a marginally viable venture. The break-
even rate is 180 tons per day or 35 million square feet of 1/2" board/annum
— 1,093,750 panels, 4' x 8' per annum. Full production of 267 tons per day,
or 79 million square feet of 1/2" board, or 2,483,624 4' x 8' panels per
year would be required.
II. Organic matrix - lumber substitute
Based on the following 1967 figures, the estimated 1975 cost of manufac-
ture for a similar facility is $4.5 million.
TABLE 39
ESTIMATE OF CONTINUOUS SHAPE FACILITY
Unloading and storage 120,000
Acid wash 75,000
Performing into line 150,000
Press line - continuous 250,000
Finishing section 150,000
auxiliary equipment 100,000
$ 845,000
80
-------
Cost Analysis Assumptions
Assume the plant cost is $4.5 million.
Material cost is $0.055 per board foot (somewhat higher than MSC found).
~^/
Assune price to retailer is $0.195 per board foot (somewhat lower MSC
figures).
Profit is $0.14 per board foot.
Operational costs as follows:
Labor $420,000/annum
Maintenance & Operating supplies 275,000/annum
Indirect Costs 322,000/annum
Depreciation 450,OOP/annum
Cost per day 5,642
The break-even production would then be:
Board feet per day: 5642/.014 = 40,300, a sufficient amount of
lumber for five (5) houses per day.
Assume full production of 500,000 board feet/day, then:
generated income = 500,000 ($0.14) = $70,000
5,642 in costs
Daily profit = 64,358, a yearly income of
$16,733,000
Assune that the lumber substitute can be marketed on a direct competitive
basis.
Using these figures, and keeping in mind that the production equipment
has not yet been designed, so that output can only be estimated, some product
potential is indicated.
III. Organic matrix - Sheet rock substitute
Costs of production
Assume the plant cost is $8 million.
Assume material cost is $0.016 sq. ft. (rice hulls) and $0.018/sq. ft.
(peanut shells).
Assume sales price to retailer is $0.033/sq. ft.
Generated differences are:
Rice hulls = $0.017/sq. ft.
peanut shells = $0.015 sq. ft.
Ttie fixed operational costs are as follows:
Labor $561,000 per year
Maint. & operational supplies 275,000 per year
81
-------
Indirect costs 429,000 per year
Depreciation 800,000 per year
Total operational costs 2,065,000 per year/260 days
Per day costs = $7,942.
Assune an additional 7% material cost added to all production. The
breakeven production rate would then be:
Rice hulls: 7,942 = 469 sq. ft./day
0.017 - (.007)(.016)
Peanut shells: 7,942 = 533,020 sq. ft./day
0.015 - (.007)(.018)
Assume full production at 800,000 sq. ft./day, then the profit is as
follows:
Rice hulls 800,000 sq. ft. (.017) = 13,600/day generated
- 7,942/day fixed cost
80/day variable cost
$ 5,578/day profit
Peanut shessl 800,000 sq. ft. (.015) = 12,000/day generated
- 7,942/day fixed cost
80/day variable cost
$ 3,978/day profit
This would generate on a yearly basis:
Rice hulls: 5,578(260) = $1,450,280
Peanut shells: 3,978 (260) = $1,034,280
These would require at the sales price of sheet rock, 7 years to pay off
the investment.
82
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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/8-77-006
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
THE FEASIBILITY OF UTILIZING SOLID WASTES
FOR BUILDING MATERIALS
Executive Summary
5. REPORT DATE
June 1977 (Issuing Date)
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
8. PERFORMING ORGANIZATION REPORT NO.
Gilbert Jackson and Sylvia A. Ware
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Ebon Research Systems
10108 Quinby Street
Silver Spring, Maryland
10. PROGRAM ELEMENT NO.
1DC618 SOS#5 Task 12 #1
20901
11. CONTRACT/GRANT NO.
68-03-2460-1 (Summary)
68-03-2056 (Research)
12. SPONSORING AGENCY NAME AND ADDRESS
Municipal Environmental Research Laboratory—Cin.,OH
Office of Research and Development
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
13. TYPE OF REPORT AND PERIOD COVERED
Executive Summary
14. SPONSORING AGENCY CODE
EPA/600/14
15. SUPPLEMENTARY NOTES
Research done by Material Systems Corporation, Escondido, California 92025
16. ABSTRACT
This report is an executive summary of a two-phase study initiated by Material
Systems Corporation and the Environmental Protection Agency to research and to
develop building materials containing organic and inorganic wastes and waste-
derived products.
The first phase covered an extensive literature search to identify, to review and to
evaluate wastes with potential as matrices, reinforcements or fillers in building
composites. Seven reinforcement candidates and five fillers were chosen for detailed
evaluation in Phase II. Two matrices were selected for further study — an organic
waste-based matrix and an inorganic matrix developed by Material Systems Corporation.
The second phase concentrated on evaluating the structural and aesthetic properties
of variously formulated composites. Limited economic analyses indicate that several
commercially viable products could be derived from wastes.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.lDENTIFIERS/OPEN ENDED TERMS C. COS AT I Field/Group
Construction materials
Fly ash
Fire resistant materials
Materials recovery
Agricultural wastes
Solid waste
Rice hulls
Resource recovery
13B
18. DISTRIBUTION STATEMENT
Release to Public
19. SECURITY CLASS (ThisReport)
Unclassified
21. NO. OF PAGES
93
20. SECURITY CLASS (Thispage)
Unclassified
22. PRICE
EPA Form 2220-1 (9-73)
83
. S. GOVERNMENT PRINTING OFFICE: !977-757-056/6't39 Region N°- 5-11
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