United States
Environmental Protection
Agency
Hazardous Waste Engineering «^
Research Laboratory """
Cincinnati OH 45268
Research and Development
EPA/600/S2-88/021 Apr. 1988
ŁEPA Project Summary
Reactivity of Various Grouts to
Hazardous Wastes and
Leachates
Andrew Bodocsi, Mark T. Bowers and Roddy Sherer
A laboratory study was conducted
to evaluate the potential of selected
grouts for controlling the percolation
of leachates from hazardous solid
waste landfills or hazardous waste
ponds. In the course of the study,
seven different grouts were
subjected to permeability tests and
four of the grouts were tested for
their reactivity by an immersion type
test. Eight different chemicals, some
with two concentrations, and two
real-site wastes were used as
permeants in the permeability tests,
and as liquids for the immersion
baths.
Of the seven grouts, the acrylate,
cement-bentonite (mix 2), and
urethane grouts had the lowest
baseline permeabilities with water,
ranging from 2.3 x 10'10 to 3.6 x
10'9 cm/sec. During permeability
testing with chemicals, the acrylate
grout exhibited excellent resistance
to the paint and refinery wastes, 25%
acetone, 25% methanol, and sodium
hydroxide. It performed satisfactorily
with cupric sulfate, ethylene glycol,
and xylene, and was seriously
damaged by aniline, 100% acetone,
hydrochloric acid, and 100%
methanol. The permeability of the
cement-bentonite (mix 2) grout was
tested with acetone, aniline, cupric
sulfate, hydrochloric acid, methanol,
and sodium hydroxide. With every
one of these chemicals the
permeability of the grout improved,
ultimately reaching a practically
impervious state. The urethane grout
maintained its low permeability with
acetone, aniline, ethylene glycol,
methanol, paint waste, refinery waste,
and hydrochloric acid and it
performed marginally well with cupric
sulfate. However, the urethane lost its
low permeability with sodium
hydroxide and xylene.
Based on the comparison of
permeability and reactivity test
results, a scheme was proposed to
correlate the permeability changes of
grouts to the weight and consistency
changes that may occur during their
reactivity testing.
This Project Summary was
developed by EPA's Hazardous Waste
Engineering Research Laboratory,
Cincinnati, OH, to announce key
findings of the research project that is
fully documented in a separate report
of the same title (see Project Report
ordering Information at back).
Introduction
One of the major environmental
problems facing the nation is the threat of
contamination of groundwater from
leaking hazardous waste landfills and
hazardous waste ponds. If a waste site is
underlain by an impervious stratum, the
most cost-effective remedy may be
using a cutoff slurry wall constructed
around the site and keyed into the
aquiclude. However, if there is no
impervious stratum below the waste, the
remedy may be the construction of a
bottom seal created by injection grouting,
in conjunction with a vertical slurry wall.
Alternately, both the bottom seal and side
wall may be made by injection grouting.
Injection grouting has been used for
many years for stabilizing soils, to
provide cutoff curtains under dams, for
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stabilizing tunnels, and more recently it
was proposed for containment of
hazardous waste.
When constructing an impervious
barrier by injection grouting under a
waste site, the grout must thoroughly
penetrate the soil. After expelling the
waste from the voids the grout must set
and harden in the soil. In addition, the
hardened grout must provide a durable
impervious seal even when permeated
by hazardous leachate.
The purpose of this study was to test
the permeability and reactivity of
selected grouts with 10 chemicals to
determine if the grouts had the durability
to withstand the typical hazardous waste
site environment, and thus could be
considered for horizontal seal con-
struction.
The permeability test results indicate
that certain grout-chemical com-
binations caused the deterioration of the
permeability of the grout, while others
resulted in little or no detrimental
changes. The reactivity test results show
what effect chemical baths had on grout
samples; some combinations caused
weight gains, others weight losses, and
still others caused no changes. In
addition, changes in sample consistency
were observed. The combined analysis
of the two tests resulted in correlations
that allow prediction of permeability
changes from reactivity test results.
Materials and Methods
All permeability tests and most
reactivity tests were conducted on
grouted soil samples. The permeability
testing was conducted in specially
constructed permeameters and safe
environmental boxes, using selected
chemicals as the permeants. The
reactivity samples were tested by their
immersion in selected chemical baths.
The detailed description of the
grouting procedure, the permeameters,
the permeability measuring apparatuses,
and the permeability and reactivity
testing procedures may be found in a
separate report of the same title as this
summary.
Grouts Used
In the typical batch of the cement-
bentonite (mix 1) grout 3000 g Type III
cement, 120 g bentonite, and 6000 ml
water was used, resulting in a water-
cement ratio of 2.0. The batches of
cement-bentonite (mix 2) grout were
made up of 3000 g MC-500 microfine
cement, 120 g bentonite, 30 ml
dispersant, and 2250 g water, yielding a
water-cement ratio of 0.86. For ease of
injection, pea gravel was used as the soil
with both grouts.
The sodium silicate grout selected
was SIROC 132*, distributed by
Raymond International, Inc. It consisted
of 60% modified silicate, 25% water,
10% formamide, and 5% calcium
chloride. A fine Mason's sand was used
as the soil to avoid syneresis. Later
extensions to the work included a
glyoxal-modified sodium silicate grout
and a sodium aluminate-modified
sodium silicate grout in order to reduce
the permeability of these grouts.
The urethane grout selected was
CR360, a product of the 3M Company. A
mixture of 89.2% water, 5.7% CR361
(gel inhibitor), and 5.1% CR360
(urethane polymer solution) was chosen.
A silica sand was used with this grout.
AC-400, distributed by Avanti
International, was chosen to represent
the acrylate grouts. A mixture of 73.44%
water, 24.99% AC-400, 0.74%
triethanolamine (catalyst), 0.74%
ammonium persulfate (initiator), and
0.074% potassium ferricyanide (inhibitor)
was used. Silica sand was used as the
soil.
Chemicals and Hazardous
Leachates Used
For this study, eight different
chemicals and two real-site leachates
were selected. Acetone, aniline, cupric
sulfate, ethylene glycol, hydrochloric
acid, methanol, sodium hydroxide and
xylene were used. The real-site
leachates used were a refinery waste and
a paint waste, which were obtained from
lysimeter studies conducted at the
Center Hill Solid and Hazardous Waste
Research Facility in Cincinnati, Ohio.
Results and Discussion
Permeability Test Results with
Water
Before the samples were tested with
chemicals, they were permeated with
deionized water to establish their
equilibrium baseline permeabilities.
Three of the grouts tested had very low
baseline permeabilities with water:
acrylate (k = 5.1 x 10"10 cm/sec),
cement-bentonite (mix 2) (k = 2.3 x
10'1° cm/sec), and urethane (k = 3.6 x
•Mention of trademarks or commercial products
does not constitute endorsement or
recommendation for use by the US
Environmental Protection Agency.
10~9 cm/sec). The permeabilities of the
other four grouts with water exceeded 1 >
10-7 cm/sec.
Permeability Test Results For
Urethane Grout with Chemicals
Figure 1 illustrates in a bar chart form
the overall permeability changes ol
urethane grout with 10 selected
chemicals. On the left vertical axis of the
chart permeability is plotted on a log
scale. On the right vertical axis the
equilibrium permeabilities of the urethane
grout samples with water are indicated
Each shaded bar represents the average
changes in the permeability of the groul
with one of the chemicals. Each bai
starts at the equilibrium permeability ol
the grout with water, and may go up 01
down, or remain unchanged, depending
on the reaction of the grout with the
specific chemical. In most cases the bat
first rises to a dashed line that represents
the permeability of the grout at the first
peak of its permeability with flow. The bar
may rise further and terminate at a
permeability level that corresponds to the
final equilibrium permeability of the groul
with the specific chemical. The number
on each line gives the number of pore
volumes of chemical which flowed
through the sample before it reached the
indicated permeability.
As shown, the urethane groul
remained quite impervious with the
majority of the chemicals. With 20%
cupric sulfate and 4N hydrochloric acid
the grout performed marginally, as its
final permeability slightly exceeded the 1
x 10'7 cm/sec level. The mosl
detrimental to the urethane grout were
the 25% sodium hydroxide and xylene
The sodium hydroxide caused a 4.5
orders of magnitude increase, raising the
equilibrium permeability of the grout tc
much above the 1 x 10~7 cm/sec level.
The bar chart in Figure 2 shows the
effects of concentration of selected
chemicals on the final permeability of the
urethane grout. As shown, varying the
concentrations can have varying effects
on the permeability of this grout.
Permeability Test Results for
Acrylate Grout with Chemicals
The acrylate grout exhibited excelleni
resistance to real-site paint and refinery
wastes, and 25% sodium hydroxide. Its
performance was satisfactory with 20%
cupric sulfate, 100 % ethylene glycol anc
xylene. The aniline 100% acetone, 4fs
hydrochloric acid, and 100% methano
were very detrimental to the permeability
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1
1
Figure 1. Permeability of urethane grout with various chemicals.
\
u
1
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of this grout. The permeability of the
grout actually decreased with the
introduction of 25% sodium hydroxide.
Permeability Test Results for
Cement-Bentonite (Mix 2)
Grout with Chemicals
With both water and chemicals, this
grout was the most impervious of all
tested. The introduction of every
chemical caused the permeability of the
grout samples to decrease from their
baseline permeabilities with water. With
very small amounts of flow of between
0.1 and 0.6 pore volumes, the
permeabilities of the samples dropped to
between 3 x 10'11 and 6 x 10'11
cm/sec, or to a practically impervious
state. Because of their very low
permeability, these samples allowed very
low flow volumes, even though they were
tested on the average for more than 120
days. It is possible that given enough
time and flow, these chemicals could
increase the permeability of the grout,
but it would take very long testing times.
Permeability Test Results for
Other Grouts with Chemicals
In addition to the above discussed
grouts, cement-bentonite (mix 1),
sodium silicate, glyoxal-modified
sodium silicate, and sodium aluminate-
modified sodium silicate grouts were also
tested.
A detailed description of the test
results, including bar chart summaries,
may be found in a separate report of the
same title as this summary.
Reactivity Tests
The objectives of the reactivity tests
were to observe the weight and volume
changes that small samples of the
various grouts underwent during their
immersion in selected chemical baths,
and to explore if these observations
could be correlated with the
corresponding permeability test results.
In this research the four grouts tested
for their reactivity were acrylate,
cement-bentonite (mixes 1 and 2), and
urethane. The testing consisted of
immersing the grout samples in selected
chemicals and weighing them after
elapsed times of 1, 7, 14, 28, 56, and 84
days. Plots of percent weight change
versus time were prepared for each
sample and replicate series. In addition,
subjective observations were made and
recorded on the shrinkage, swelling,
spelling, hardening, softening and
stickiness of the samples. The results
ranged from total disintegration to as
much as a 40% weight increase.
Comparative Analysis of
Permeability and Reactivity
Tests
The results from the two types of tests
were analyzed, compared, and a scheme
was proposed to allow the prediction of
the permeability behavior of grouts with
various chemicals from their behavior
with the same chemicals in the reactivity
tests. This scheme is summarized in
Table 1, where weight and volume
changes in the vertical columns, and
consistency changes in the horizontal
rows are correlated with permeability
changes indicated in the boxes. For
example, the urethane samples in xylene
baths underwent medium (10%, authors'
classification) weight losses, and they
also became hard. This case
corresponds to the matrix location of
column 2 and row 2, which reads:
"Permeability increases significantly."
Indeed, going back to Figure 1, it is seen
that the permeability of the urethane
grout with xylene increased almost three
orders of magnitude before it came to an
equilibrium. It is proposed that with the
presented correlations, the choice of the
most suitable grout for a site could
possibly be made based on reactivity
tests only, and furthermore, the tests
could be conducted at the site of the
hazardous waste.
Conclusions
1. When tested for permeability, the
urethane grout remained quite
impervious with the majority of the
chemicals tested, except it
performed only marginally with a
20% solution of cupric sulfate and
the 1N and 4N concentrations of
hydrochloric acid, and poorly with
the 25% solution of sodium
hydroxide and reagent grade xylene.
2. The acrylate grout exhibited
excellent to satisfactory resistance to
all chemicals, except reagent grade
aniline, 100% acetone, 1N and 4N
concentrations of hydrochloric acid,
and 100% methanol. These caused
increases of several orders of
magnitude in its permeability.
3. With all the chemicals tested, the
permeability of the cement-
bentonite (mix 2) grout decreased
from its baseline permeability with
water to a practically impervious
permeability of approximately 3 x
10'11 cm/sec.
4. The effects of the concentration o
chemicals on the permeability o
grouts varied. It was found from the
limited data that certain chemical;
with reduced concentrations causec
smaller increases in the permeability
of grout than those with highe
concentrations, while varying the
concentration of other chemicals hac
no significant effects on the
permeability of the grout.
5. From the analysis of reactivity anc
permeability test results, a scheme
was proposed that correlates the
weight and consistency changes o
the reactivity samples of a grou
immersed in a chemical to expectec
changes in its permeability wher
permeated by the same chemical
This may allow an engineer to make
at least the preliminary selection o
suitable grouts for a site by usinc
reactivity tests in place of the more
costly permeability tests.
The full report was submitted ir
fulfillment of Contract No. 68-03-3210
Work Assignment 13, by the University ol
Cincinnati under sponsorship of the U.S
Environmental Protection Agency.
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Table 1. Predicted Permeability Behavior Based on Reactivity Test Results
^Weight/Volume
^Changes
Consistency^
Changes
Volume
Increase/Weight
Gain
Volume
Decrease/Weight
Loss
Weight Loss by
Spalling
Initial Volume
Increase, Later
Shrinkage (Initial
Weight Gam, Weight
Loss as Tesf
Proceeds,)
Initial Volume
Decrease, Later
Volume Increase
(Initial Weight Loss,
Weight Gain as Test
Proceeds)
None
Remains hard or
becomes hard
Softens
Softens quickly
Softens slowly
Disintegrates
Moderate increase
in permeability
Permeability
increases
significantly
Permeability
decreases
somewhat, or at
worst, increases
minimally
Considerable
increase in
permeability
Permeability
affected minimally
Large increase in
permeability
Increase in
permeability is small
Increase in
permeability is large
Moderate increase
in permeability
Permeability
increases greatly
&U. S. GOVERNMENT PRINTING OFFICE: 1988/548-158/67118
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