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ORIGINAL ARTICLE
Strength and mechanical behavior of soil–cement–lime–ricehusk ash (soil–CLR) mixture
Younes Bagheri • Fauziah Ahmad •
Mohd Ashraf Mohamad Ismail
Received: 1 November 2012 / Accepted: 7 March 2013
� RILEM 2013
Abstract This study presents results of geotechnical
investigations on treated silty sand soil with cement,
lime and rice husk ash (CLR) and cement-lime (CL)
admixture. Consolidated undrained triaxial test and
unconfined compressive test were performed to esti-
mate the potential of CLR and CL. The study
investigates the influence of the amount of CLR%,
main effective stress and curing days on soil strength,
deformation, post peak behavior and brittleness. The
percentages of the additives of CLR and CL varied
from 2.5 to 12.5 % by dry weight of the soil with dry
densities of 14.5 kN/m3 and the curing times of 3, 7,
28 and 60 days were examined. From the results, the
stress–strain response is strongly influenced by the
CLR contents and effective confining pressure.
Strength and post peak strength of the CLR–soil are
greatly improved by an increase in binder content. An
increase of the effective cohesion c0 (kPa) and
effective friction U0 (degree) is observed with increas-
ing the CLR content, consistently. Brittle behavior
observed at lower confining pressures and high CLR
content. For both CLR and CL additives, linear trend
was observed for variation of the qu (kPa) with respect
to the additives percentages. RHA was also found to be
effective in increasing the shear strength of CLR–soil
mixture.
Keywords Silty � Sand soil � Stabilization � Rice
husk ash � Shear strength
Abbreviations
CLR Cement, lime and RHA content
CL Cement and lime content
UCS Unconfined compressive strength
CU Consolidated undrained triaxial compression
test
PI Plasticity index and
RHA Rice husk ash
List of symbols
Dr Relative density
Gs Specific gravity
GsCLR Specific gravity of CLR
IB Brittleness index
d50 Main particle diameter
qp Peak deviator stress
qr Residual deviator stress
qu Unconfined compressive strength
R2 Coefficient of determination
c0 Effective cohesion
U0 Friction angle
r0 Effective principal stress
Y. Bagheri � F. Ahmad (&) � M. A. M. Ismail
School of Civil Engineering, USM Engineering Campus,
University Sains Malaysia (USM), 14300 Nibong Tebal,
Penang, Malaysia
e-mail: [email protected]
Y. Bagheri
e-mail: [email protected]
M. A. M. Ismail
e-mail: [email protected]
Materials and Structures
DOI 10.1617/s11527-013-0044-2
s Shear stress at failure and
cd Dry unit weight
1 Introduction
Soil has been used as a base material in various
engineering infrastructures such as retaining walls,
pavements, water ways, irrigation and drainage net-
works, protective barrier and embankments. Particular
attention has been turn to the mechanical and chemical
stabilization of soil [1–3] in order to increase the soil
strength (s). However, the economic aspects of soil
stabilization projects limit the application of mechan-
ical approach. Regarding to the chemical stabilization
viewpoint, several additives such as cement, lime,
polymers and fly ash have been utilized. Cement and
lime are the most common additives amongst the
mentioned materials that produce positive effect on
soil performance [1, 4–8]. Cement and lime signifi-
cantly decrease the swell potential, plasticity index
(PI), increase the modulus of elasticity (Es), durability
index (Id) and shear strength of soils (s) [5, 9]. In recent
years, many investigations have been conducted on the
solution of environmental and economic problems due
to chemical stabilizers applications. Using the waste
natural material is one of the most effective approaches
in soil improvement as a green method. Agricultural
activities provide various waste natural materials such
as bran and husk. Paddy farms are composited of
5–8 % of bran, 72 % of rice and 20–22 % of husk on an
average by weight, that cause to generate rice husk ash
(RHA) as an alternative additive to eliminate the
chemical additives problems [10–12]. RHA contains
high amount of silica (87–97 % of SiO2) and thus can
be used as a pozzolanic material in lime and cement
mixture. During last few decades, different investiga-
tions on RHA performance in soil stabilization have
shown that RHA can be considered as a pozzolan
promising material with cement or lime as it can
improve the soil engineering properties [12–16] and
also reduce cement and lime consumption in soil
stabilization and concrete technology as well [13, 17].
Using RHA as a supplementary cementitious material
leads to a reduction in greenhouse gases (carbon
dioxide) emissions fallowing by the cement and lime
production [18–20]. Besides, it is figured out that
carbon remained in the ash is trapped in the soil or
concrete and won’t be distributed in atmosphere which
is environmentally so momentous [18].
The different amount of chemical additives and
curing time are also significant variable parameters
which render different reactions for treated soils [21–23].
By consideration on past investigations, it was
found that no treated soil with the combination of
cement–lime and RHA (CLR) has been utilized yet.
The present experimental work investigates the defor-
mability properties and shear strength of soil–CLR. In
addition, the effect of RHA was investigated on soil
strength.
2 Experimental works
2.1 Combined mixture preparation
According to the Unified Soil Classification System
(USCS), the studied soil was classified as silty sand
(SM) [24] with specific gravity (Gs) of 2.55. The
investigated grain-size distribution is plotted in Fig. 1.
The soil sample has 11.9 % gravel (D [ 2 mm),
37.7 % medium sand (0.425 \ D \ 2 mm), 14 % fine
sand (0.075 \ D \ 0.0425 mm), 28.6 % silt (0.002 \D \ 0.075 mm), and 7.8 % clay (D \ 0.002 mm),
with the main particle diameter d50 of 0.42 mm. The
geotechnical properties of the studied soil are summa-
rized in Table 1. Furthermore, in Table 2 the miner-
alogical composition of soil is presented according to
the soil analysis methods [25]. This soil consists of
*88 % silica and sesquioxides of iron and aluminum.
Accordance to Table 2, this soil is classified as
lateritic, because, the red or reddish brown, weathered
soils contain of silica to sesquioxide ratios between
1.33 and 2.0 are classified as laterite or lateritic soils
and those with ratios more than 2.0 are named
nonlateritic. Moreover, this soil is acidic (pH \ 5)
based on the soil pH classification [26].
The ordinary Portland cement that was used has a
specific gravity (Gs) of 3.05. Hydrated high calcium
lime [Ca(OH)2] was used with a Gs of 2.14. Lime and
cement materials were passed through sieve No. 40
before usage.
Rice husk was burned in the gas furnace to produce
ash (RHA) at 500 �C for a period of 120 min with high
pozzolanicity, maximum fineness and silica quantity
(&90 %) [12, 27]. The specific gravity of RHA is
1.42. To measure pozzolanic activity of RHA the
Materials and Structures
strength activity index method was utilized, according
to ASTM C 311-11a [28]. This index is determined by
comparing the compressive strengths of cement mor-
tars with 15 % pozzolan and without it. According to
the standard, the pozzolanic activity index of the
sample which contains pozzolan should be more than
75 % after 28 days of curing. In this research, the
pozzolanic activity index of RHA after 7 and 28 days
of curing was estimated 79 and 88 % respectively.
In this work, the behavior of a combined additive of
cement, lime and RHA materials known as CLR were
investigated. To quantify the behavior of soil–CLR
mixture, the factors of deformability, soil strength
parameters (U0 and c0) and brittleness index (IB) were
investigated.
To find the best mixture of cement, lime and RHA in
combination with soil, unconfined compression strength
test (UCS) was employed for different percentage of the
studied mixtures. Tests were conducted on similar
conditions which is cd = 17 kN/m3, CLR by 10 %
weight and 28 days curing time. The mixtures with
higher values of cement show a considerable value of
qu (kPa) but resulted in negative economical and
environmental issues (Table 1). Therefore, the com-
bination of 25 % cement, 50 % lime and 25 % RHA as
the best mixture was selected for this investigation
(Table 1). The properties of the studied soil–CLR
combination are summarized in Table 1.
2.2 Experimental design
Consolidated undrained (CU) triaxial tests and UCS
were carried out to evaluate the mechanical behavior
Fig. 1 Grain size distribution for the studied soil
Table 1 Summary of the properties of the investigated soil, additives and mixture
Soil properties Quantity Additives properties Quantity/
qualitative factor
Mixture percentage;
CLR (A/B/C)aqu
(kPa)
Specific gravity 2.55 Specific gravity 2.17 (15/50/35) 673
Sand (%) 51.70 Cement (% by weight) 25 (25/50/25) 1014
Silt (%) 28.60 Lime (% by weight) 50 (35/50/15) 1582
Clay (%) 7.80 RHA (% by weight) 25 (25/40/35) 1005
USCS classification SM Fineness passing 45 lm (%) 76 (35/40/25) 1649
pH 12.43 (35/30/35) 1898
Liquid limit (%) 48.05 Color Gray (15/60/25) 457
Plastic limit (%) 31.50 (25/60/15) 828
PI (%) 16.53
Optimum moisture (%) 16.30
Maximum dry density (kN/m3) 17.52
Minimum dry density (kN/m3) 10.34
a The signs of A, B and C show the percentage of the cement, lime and RHA, respectively
Table 2 Chemical and mineralogical of the soil
Properties Value
Silica (SiO2) 57.1 (%)
Alumina (Al2O3) 21.6 (%)
Iron oxide (Fe2O3) 9.70 (%)
Potash (K2O) 0.13 (%)
Magnesia (MgO) 0.16 (%)
Calcium oxide (CaO) 0.12 (%)
Silica: sesquioxide ratio 1.82
pH 4.76
Materials and Structures
of CLR–soil and CL–soil. The performance of the
additives percentage, main effective stress and curing
days on soil strength, deformation, post peak behavior
and brittleness were investigated. The experimental
test program is summarized in Table 3.
2.3 CU triaxial test
The specimens were prepared by mixing oven-dry soil
and optimum water content of 16.3 %, with 2.5, 5, 7.5,
10 and 12.5 % of CLR thoroughly until a uniform color
was observed. The diameter and height of the samples
prepared for the triaxial test were 70 and 140 mm
respectively. Each sample was immediately com-
pacted (based on standard method [29]) after mixing
in three layers of 47 mm thickness in a rigid cylindrical
mold to the dry density of 14.5 kN/m3 (i.e., a relative
density of Dr = 70 %). The mixing and compaction
were completed within an hour to avoid large amount
of water losses. After compaction, the specimens were
kept in the mold for about 12 h. Finally, the specimens
were then removed from the mold and immediately
wrapped in rubber membrane and cured in a covered
container with a wet sponge in humid room at 26 �C
� 2 �C to avoid significant changes in moisture
content until testing at 3, 7, 28 and 60 days. The
sample was weighted prior to the test in order to
control the moisture of the sample. It was found that
the moisture lost is\1 % compared with the reading
recorded during preparation day. The similar samples
prepared for this investigation were kept in the same
condition (moisture content, density and curing time)
to minimized effects on the test results.
In order to evaluate the soil stress–strain and strength
behavior, a series of CU triaxial tests with pore-pressure
measurement were carried out according to the standard
[30] on untreated and treated soil specimens with
various percentages of CLR content. Before starting the
test, freshly de-aired water is drawn into the triaxial cell
and the tests were fully controlled by data acquisi-
tion. During the saturation process, the samples were
fully saturated by applying a cell pressure and a back
water pressure to achieve a B value of at least 0.95. The
complete saturation process for each sample requires
about 2–3 days. Then, the samples were consoli-
dated under a specific isotropic confining pressure.
The consolidation stage is completed when the excess
pore-water pressure had dissipated completely and the
water volume changes remain constant. Finally, when
consolidation condition is achieved, the specimen was
loaded vertically in strain controlled condition with a
low axial strain rate of 0.02 mm/min under the confining
pressure of 50, 100 and 250 kPa. Shearing is complete
when the axial strain reached 25 % or the deviator stress
reached a constant value. In this investigation, the area
corrections and membrane adopt the suggestions pro-
posed by La Rochelle et al. [31].
2.4 Unconfined compression test
First, dried soil was passed through the sieve # 6. The
largest soil particle diameter must be smaller than 1/6
mold diameter [32]. Test specimens were obtained by
mixing oven-dry soil and the determined quantities of
CLR as long as the mixture acquired a uniform color
and consistency. The amount of additives for each
Table 3 Experimental
program summaryVariable Consolidated undrained
triaxial test
Unconfined
compression test
Initial mean effective stress 50, 100, 250 kPa 0 kPa
CLR content (%) 2.5, 5, 7.5, 10, 12.5 5, 7.5, 10, 12.5
Curing time with CLR (days) 3, 7, 28, 60 7, 28, 60
CL content (%) 10, 12.5 5, 7.5, 10, 12.5
Curing time with CL (days) 3, 7, 28 7, 28, 60
Degree of saturation (%) – [95
Rate of strain (mm/min) 0.02 1
Soil type SM SM
Relative density (%) 70 70
Water content (%) 16.3 16.3
Standard method ASTM D4767 ASTM D2166
Materials and Structures
specimen was determined based on the weight of dry
soil. The tests were carried out on soils treated with 5,
7.5, 10 and 12.5 % of CLR by weight. Each specimen
used for the determination of UCS was compacted in 3
layers with 25 mm thickness in a rigid cylindrical mold
to a target dry density (14.5 kN/m3) with optimum
water content of the untreated soil (16.3 %). The height
and diameter of the samples prepared for the UCS test
were 76 and 38 mm respectively. After completion of
the compaction, specimens were immediately cured in
a covered container with a wet sponge in humid room at
26 �C � 2 �C to prevent significant changes in mois-
ture content until testing at 7, 28 and 60 days.
Unconfined compression test was performed on
treated SM samples with CLR to evaluate the influ-
ences on CLR content and curing time on the strength
of each specimen. The compressive strength test was
carried out using an automatic loading machine with
axial loading speed at a rate of 1 mm/min and
maximum capacity of 10 kN. During UCS tests,
failure compressive load and deviator stress were
recorded. For each case, three specimens were tested
and each sample with the same condition should not be
different from the mean strength by more than 10 %
[33].
The same analogy with soil–CLR preparation was
used for preparing the soil–cement and lime mixture
(soil–CL) samples to investigate the RHA effect on
soil properties.
3 Observations and discussions
3.1 CU triaxial compression test
The variation of deviator stress–strain and pore-water
pressure with respect to axial strain for both untreated
(CLR = 0 %) and treated specimens with 10 % CLR
after 28 days curing is plotted in Fig. 2. The data are
derived from CU triaxial compression test.
Figure 2a, c indicates that the deviator stress–strain
and pore-water pressure behaviors for untreated spec-
imens echo the ductile material acting manner. Both
deviator stress (kPa) and pore-water pressure (kPa)
Fig. 2 The variation of
pairs [deviator stress (kPa)-
strain (%)] and [pore–water
pressure (kPa)-strain (%)]
a Soil deviator stress (kPa)–
strain (%) with 0 % CLR,
b soil deviator stress (kPa)–
strain (%) with 10 % CLR
after 28 days curing, c soil
pore–water pressure (kPa)–
strain (%) with 0 % CLR,
d soil pore–water pressure
(kPa)–strain (%) with 10 %
CLR after 28 days
Materials and Structures
significantly increased at failure by addition of CLR
and curing time. The improvement in shear strength for
CLR addition is due to the development of more
cementation in the stabilized matrix. Furthermore, the
increase of ductility for treated specimens will results
in confining pressure redundancy since denser speci-
mens will emerge due to high confining pressure.
Higher brittle response of the specimens were observed
at lower confining pressure whereas deviator stress was
significantly reduced after peaking deviator stress as
shown in Fig. 2b. Although post peak strength is
reduced, nevertheless, this factor is always being found
more than untreated specimens.
Figure 3 shows the variation of pairs stress–strain
and pore-water pressure-strain for different CLR con-
tents (%) at a constant confining pressure (= 100 kPa)
after 28 days curing.
The similar tendencies have been observed for
other confining pressures (= 50 and 250 kPa) but is not
shown for the sake of conciseness. These results
provide evidence for soil strength enhancement and
pore-water pressure growth due to strong cementation
effects caused by the increment of CLR content. It is
observed that the increment of pore water pressure
(kPa) is related to the development of linkage amongst
the particles created by CLR. The observed trend
includes two different behaviors of rapidly increasing
and gradually decreasing followed by leveling off at
constant values. The maximum value of pore-water
pressure (kPa) depends on the amount of confining
pressure. The maximum values of pore-water pressure
(kPa) for 10 % CLR contents were found to be
approximately two times more than the untreated
specimens. Table 4 presents the deviator stress values
at failure level for CLR stabilized specimens after 3, 7,
28 and 60 days curing. The considerable effect of
different confining pressure on deviator stress can also
be seen in Table 4.
The deviator stresses at failure increases as the CLR
and curing days, from 3 to 28 days increase. For
60 days curing, a distinct increase in the deviator stress
for 10 % CLR content was observed. However, the
decrement of deviator stress when CLR content varied
from 10 to 12.5 % for 60 days curing is discernable.
This attributes to the pH of CLR–soil mixture. The
highest chemical activation of lime with soil has a
value of pH = 12.3–12.4 [34], because silica has high
level of solubility in the mixture. Figure 4 illustrates
the variation of pH with respect to CLR content in
different days of curing where the proper value of pH
can be observed for value of CLR = 10 %.
Figure 5a, b presents the Mohr–Coulomb failure
criterion (Mohr envelope) for the studied combined
soil–CLRs at 28 days curing and different curing time.
The effective angle of internal friction U0 (degree) and
effective cohesion c0 (kPa) from CU triaxial tests were
estimated by drawing the Mohr–Coulomb failure
envelopes tangentially to the Mohr circles at different
confining pressures.
It can be concluded that, the effective cohesion c0
(kPa) increases as the CLR content increases (Fig. 6a).
However, the trends for different curing days were
similar but in different growth rates. For curing days of
7 and 28, the data levels to a constant value of effective
cohesion about 100 kPa. It can be seen that, the
observed increasing behavior of cohesion against CLR
is a result of bonding improvement amongst the
mixture particles.
Figure 6b shows the variation of friction angle U0
(degree) with respect to CLR content. For curing time
Fig. 3 The variation of
pairs [deviator stress(kPa)–
strain(%)] and [pore–water
pressure(kPa)–strain(%)] in
the triaxial CU test under
100 kPa confining stress on
untreated and treated
Materials and Structures
of 28 days, a relatively rapid increase was observed in
the variation of friction angle for 0 \ CLR \ 10 and
then stabilized at around 34� (Fig. 6b). For curing of 3
and 7 days with values of CLR \ 10, the variation of
Friction angle is independent from CLR variation
(Fig. 6b). A distinctive increase in friction angle can
be found for CLR [ 10 %. This behavior can be
attributed to the pH effect.
The brittleness index IB is defined as the following
equation [35]:
IB ¼qp � qr
qp
ð1Þ
where, qp, and qr are the peak deviator stress and
residual deviator stress, respectively. The variation of
IB with respect to confining pressures for the studied
CLR (%) and curing times is shown in Fig. 7. The
variation of IB are similar for curing times of 3 and
7 days, whereas larger values were observed for 28
and 60 curing days (Fig. 7c, d). This increment is
significant in the lower studied percentages of CLR
(2.5 and 5 %) (Fig. 7c).
The ductility or rigidity of the specimens can be
assessed by brittleness index. If the IB of specimen is
close to zero this means that the specimen indicates a
ductile behavior. The ultimate post peak strength in all
tests varies within a narrow range from 140 to 210 kPa
compared to the peak strength (gray line, Fig. 3a) and
thus the brittleness increases as a function of peak
strength. As a conclusion, the increase of brittleness
does not have an effect on the total strength and
functionality of the treated soil.
To evaluate the performance of RHA on soil
strength, the variation of pairs (stress–strain) and (poreTa
ble
4D
evia
tor
stre
ssat
fail
ure
lev
el
Mix
ture
Cu
rin
gp
erio
d(d
ays)
3d
ays
curi
ng
7d
ays
curi
ng
28
day
scu
rin
g6
0d
ays
curi
ng
r 3=
50
(kP
a)
r 3=
10
0
(kP
a)
r 3=
25
0
(kP
a)
r 3=
50
(kP
a)
r3
=1
00
(kP
a)
r3
=2
50
(kP
a)
r3
=5
0
(kP
a)
r 3=
10
0
(kP
a)
r 3=
25
0
(kP
a)
r 3=
50
(kP
a)
r3
=1
00
(kP
a)
r3
=2
50
(kP
a)
So
il–
2.5
%C
LR
95
.81
39
.02
81
.71
11
.51
56
.83
06
.11
37
.11
99
.73
85
.5–
––
So
il–
5%
CL
R1
21
.31
63
.42
96
.81
59
.92
08
.53
56
.82
32
.63
12
.14
59
.7–
––
So
il–
7.5
%C
LR
17
8.6
24
0.4
35
1.1
26
1.0
32
0.9
46
5.4
37
1.4
46
9.2
59
5.2
––
–
So
il–
10
%C
LR
23
6.2
33
4.4
46
7.0
34
0.5
42
6.5
55
8.1
43
6.2
56
0.9
72
7.5
49
9.5
62
4.8
77
7.9
So
il–
12
.5%
CL
R2
42
.93
51
.24
96
.53
61
.44
66
.56
01
.34
25
.95
34
.97
21
.54
79
.25
91
.47
41
.6Fig. 4 The variation of the pH with respect to CLR content in
different days curing
Materials and Structures
Fig. 5 Variation of the shear strength s (kPa) with respect to the r0 (kPa), a for all the studied combined soil–CLR samples at 28 days
curing, b in different curing days at CLR = 10 %
Fig. 6 Variation of soil
strength parameters with
respect to the CLR
percentage content in
different curing times, 3, 7
and 28 days, a effective
cohesion c0 (kPa),
b effective friction U0
(degree)
Fig. 7 Variation of the
brittleness index (IB) for
treated soils with respect to
the CLRs contents at
different confining pressures
and curing times, a 3 curing
days, b 7 curing days, c 28
curing days, d 60 curing
days
Materials and Structures
water pressure–strain) for CLR and CL treated spec-
imens in 50 kPA confining pressure, after 28 days
curing, are plotted in Fig. 8. It can be stated that, the
deviator stress values at failure and maximum pore
water pressure are higher when CLR is used with the
combination of cement and lime.
The soil strength parameters for soil–CLR and soil–
CL treated are presented in Table 5. The results
demonstrate that the effective friction angle changes
from 25.85� to 30.66� for soil–CL and 26.75–34.22�for soil–CLR (depending on the additives percentage
and curing time). The effective cohesion rising rate of
soil–CLR treated is higher than the CL-treated soil.
The effective cohesion of specimens treated with
12.5 % CLR and cured for 7 days were estimated at
102 kPa was compared with the specimens treated
with CL at the same condition and it was found that,
the effective cohesion improved *30 % (Table 5).
Thus, it is clearly observed the more efficiency of CLR
on soil treatment compared to soil treated by CL.
3.2 UCS
Figure 9a, b present the effect of the studied additives
(CLR and CL) on UCS (kPa) factor. Results of the
UCS tests show noticeable achievement of higher qu
(kPa) by adding RHA to the samples. For both CLR
and CL, a linear trend was observed for variation of qu
with respect to percentages of the investigated addi-
tives. Overall, a higher growth rates can be found for
linear trends as the curing time increases in both CLR
and CL. However, for CLR the qu increases more
rapidly compared to CL samples with respect to the
percentage of additives.
Strength of the treated soil increased due to the
adding of CLR as presented in Fig. 9. In order to explain
the prescribed response of treated soil using CLR, high
amount of silica in RHA (90 %) was considered.
Addition of RHA to lime–soil blended with water
increases the pozzolanic reaction due to the reaction
between Ca(OH)2 and SiO2 [9, 36]. This eventually
leads to the formation of cementations bonds through
the production of cement material including calcium-
silicate-hydrates. Subsequently, cement helps to com-
pound the finer particles together to form larger
aggregates in CLR–SM blends [3, 16]. Besides, as
shown in Fig. 9 and comparing the results of CLR and
CL in different curing times on soil strength (qu),
another important point is distinguished which is
utilizing RHA to reduce cement and lime consumption.
For instance, average strength of 60 days cured samples
with 12.5 % CL is approximately equal with those with
7.5 % CLR and 60 days curing (qu = 516 kPa)
(Fig. 9). It means by adding RHA, which is a waste
material and a cause of environmental pollution, there
has been a 60 % reduction in cement and lime
consumption and it is both environmentally and
economically important and reasonable.
4 Conclusions
This research highlights the responses of soil stabi-
lized by a new combined additive (CLR) in terms
strength behavior, deformability, post peak and brit-
tleness. Based on the results, the following remarks
can be concluded:
• The untreated soil presents a ductile behavior. The
peak strength increases by the addition of CLR
content. The post peak strength of treated speci-
mens was found to be more than the untreated
specimens.
Fig. 8 Comparison results
of triaxial CU test under
50 kPa confining stress on
both treated samples of CLR
and CL: a deviator stress,
b change in pore-water
pressure
Materials and Structures
Ta
ble
5T
he
soil
stre
ng
thp
aram
eter
sfo
rso
il–
CL
Ran
dso
il–
CL
trea
ted
fro
mth
etr
iax
ial
CU
test
Tes
t
iden
tifi
cati
on
s
(CL
R-A
/B/C
)
Dev
iato
rst
ress
atfa
ilu
re
(kN
/m2)
Eff
ecti
ve
Fri
ctio
nan
gle
(deg
rees
)
Eff
ecti
ve
coh
esio
n
(kN
/m2)
Ult
imat
e
dev
iato
r
stre
ss(k
N/m
2)
Tes
t
iden
tifi
cati
on
s
(CL
-A/B
/C)
Dev
iato
rst
ress
atfa
ilu
re
(kN
/m2)
Eff
ecti
ve
fric
tio
n
ang
le(d
egre
es)
Eff
ecti
ve
coh
esio
n
(kN
/m2)
Ult
imat
e
dev
iato
r
stre
ss(k
N/m
2)
(CL
R-1
0/5
0/3
)2
36
.22
6.7
56
5.4
89
0.0
6(C
L-1
0/5
0/3
)2
10
.52
7.1
44
8.3
77
1.4
2
(CL
R-1
0/1
00
/3)
33
4.4
26
.75
65
.48
11
4.8
3(C
L-1
0/1
00
/3)
30
8.3
27
.14
48
.37
11
1.5
7
(CL
R-1
0/2
50
/3)
46
7.0
26
.75
65
.48
23
3.3
9(C
L-1
0/2
50
/3)
46
5.5
27
.14
48
.37
28
5.7
1
(CL
R-1
0/5
0/7
)3
40
.52
7.3
89
8.0
11
33
.18
(CL
-10
/50
/7)
31
5.2
25
.64
92
.68
22
7.7
2
(CL
R-1
0/1
00
/7)
42
6.5
27
.38
98
.01
16
9.1
6(C
L-1
0/1
00
/7)
40
2.6
25
.64
92
.68
23
8.4
1
(CL
R-1
0/2
50
/7)
55
8.1
27
.38
98
.01
28
4.9
9(C
L-1
0/2
50
/7)
51
0.9
25
.64
92
.68
35
2.6
0
(CL
R-1
0/5
0/2
8)
43
6.2
34
.22
10
8.8
01
01
.60
(CL
-10
/50
/28
)4
07
.13
0.6
69
9.7
01
49
.57
(CL
R-1
0/1
00
/28
)5
60
.93
4.2
21
08
.80
18
5.1
1(C
L-1
0/1
00
/28
)4
69
.63
0.6
69
9.7
02
77
.07
(CL
R-1
0/2
50
/28
)7
27
.53
4.2
21
08
.80
29
5.6
2(C
L-1
0/2
50
/28
)6
93
.33
0.6
69
9.7
04
34
.61
(CL
R-1
2.5
/50
/3)
24
2.9
27
.43
78
.02
96
.55
(CL
-12
.5/5
0/3
)2
28
.22
6.4
06
6.6
81
66
.44
(CL
R-1
2.5
/10
0/3
)3
51
.22
7.4
37
8.0
21
49
.93
(CL
-12
.5/1
00
/3)
29
4.8
26
.40
66
.68
20
2.7
8
(CL
R-1
2.5
/25
0/3
)4
96
.52
7.4
37
8.0
22
68
.90
(CL
-12
.5/2
50
/3)
41
8.5
26
.40
66
.68
30
0.2
3
(CL
R-1
2.5
/50
/7)
36
1.4
29
.68
10
2.0
01
50
.83
(CL
-12
.5/5
0/7
)3
20
.92
5.8
57
8.2
51
88
.61
(CL
R-1
2.5
/10
0/7
)4
66
.52
9.6
81
02
.00
16
2.8
9(C
L-1
2.5
/10
0/7
)4
05
.12
5.8
57
8.2
52
38
.64
(CL
R-1
2.5
/25
0/7
)6
01
.32
9.6
81
02
.00
26
3.1
4(C
L-1
2.5
/25
0/7
)4
96
.22
5.8
57
8.2
53
49
.25
(CL
R-1
2.5
/50
/28
)4
25
.93
4.0
29
7.8
31
67
.35
(CL
-12
.5/5
0/2
8)
37
3.2
28
.52
89
.60
16
7.2
1
(CL
R-(
12
.5/1
00
/28
)5
34
.93
4.0
29
7.8
31
96
.73
(CL
-12
.5/1
00
/28
)4
08
.62
8.5
28
9.6
02
63
.14
(CL
R-1
2.5
/25
0/2
8)
72
1.5
34
.02
97
.83
33
1.2
4(C
L-1
2.5
/25
0/2
8)
55
1.8
28
.52
89
.60
29
3.7
3
CL
Ro
rC
L-A
/B/C
:A
per
cen
to
fad
dit
ives
(CL
Ro
rC
L),
Bco
nfi
nin
gp
ress
ure
ink
N/m
2,
Cd
ays
of
curi
ng
Materials and Structures
• The increase of CLR additive percentage and
curing time substantially increases the deviator
stress peak of the soil up to 10 % of the CLR
content. The deviator stress when CLR content
changes from 10 to 12.5 % for 60 days curing is
discernable. This attributes to the pH of the soil–
CLR mixture.
• The effective cohesion c0 (kPa) and effective
friction angle U0 (degree) increase when the CLR
content (%) increases.
• Brittle behavior is observed at a lower confining
pressures and higher CLR content (%).
• A linear trend is observed for the variation of both
CLR and CL additives percentages with respect to
qu (kPa).
• Results show that the RHA significantly increases
the shear strength of soil–CLR mixture and
reduces the cost and environmental impact of
cement and lime additives.
Acknowledgments The authors are grateful to Universiti Sains
Malaysia (USM) for their financial support and geotechnical
laboratory technicians for their assistance. The authors are also
grateful to the anonymous reviewers of the paper for their valuable
comments that improve the original manuscript.
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