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Reexamination of Lime Stabilization Mechanisms of Expansive Clay
Zhao Honghua1, Liu Jun2, Guo Jing3, Zhao Chunji4, Gong Bi-wei5,
1Lecturer, Department of Engineering Mechanics, Dalian University of Technology, Dalian,
China, 110624. E-mail: zhaoh@dlut.edu.cn
2Geotechnical Engineer, Key Laboratory of Geotechnical Mechanics & Engineering of MWR,
Changjiang River Scientific Research Institute, Wuhan, China, 430010
3Graduate student, Department of Engineering Mechanics, Dalian University of Technology,
Dalian, China, 110624
4Graduate student, Department of Engineering Mechanics, Dalian University of Technology,
Dalian, China, 110624
5Professor, Key Laboratory of Geotechnical Mechanics & Engineering of MWR, Changjiang
River Scientific Research Institute, Wuhan, China, 430010
Abstract
For the purpose of understanding the mechanism of lime treatment on expansive soil,
a series of tests were conducted on selected Nanyang expansive clay. X-ray diffraction
test indicated that the major clay minerals of Nanyang expansive clay are a mixture of
illite and smectite with some kaolinite and chlorite. The scanning electron microscope
images obtained at different curing times were used to interpret the microstructure
change and the formation of new products for the lime treated samples. Atomic
absorption method was adopted to test the concentration of Ca2+ and K+ in the pore
water and exchange complex of lime treated Nanyang expansive clay. The results
indicate that: (1) cation exchange, ions crowding, formation of Ca(OH)2.nH2O,
agglomeration, broken of clay particles in high pH environment are the dominant
reactions at early stage for lime treatment on expansive clay; (2) pozzolanic reaction
and carbonation happened at late stage after lime treatment (90 days in this study) .
Journal of Materials in Civil Engineering. Submitted October 20, 2013; accepted January 24, 2014; posted ahead of print January 27, 2014. doi:10.1061/(ASCE)MT.1943-5533.0001040
Copyright 2014 by the American Society of Civil Engineers
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Keywords: Lime, Nanyang Expansive Clay, X-Ray Diffraction Analysis, Cation
Exchange, Scanning Electronic Microscopy, Atomic Absorption
Introduction
For centuries, lime has been applied to clay soils to improve its strength and stiffness
properties and to reduce the swell-shrink potential of expansive soils (Holtz 1969;
Bell 1988b; Chaddock 1996; Snedker 1996; Rao 2005; Rao and Thyagaraj 2003).
Lime can be applied either in a form of quicklime or as hydrated lime. Lime increases
strength and stiffness of soils through pozzolanic reaction, cementation and
carbonation (Bell 1996; Rajasekaran and Rao 2000; Consoli et al. 2011; Dash and
Hussain 2012). Curing at high temperature also speeds up the increase of strength for
lime treated clay (Toohey et al. 2013; Rao and Shivananda 2005; Boardman et al.
2001). The cementation is mostly brought by pozzolanic reactions and can
significantly improve the long-term performance of the stabilized soils (Rogers et al.
2006; Khattab et al. 2007). Lime precipitation technique in stabilizing expansive soil
can promote lime-soil pozzolanic reactions and increase the unconfined compressive
strength of expansive soils (Thyagaraj et al. 2012). However, excessive lime will
cause strength decrease of treated soil (Dash and Hussain 2012). Lime can reduce
liquid limit and the plasticity of soils (Bell 1988; Herrin and Mitchell 1961; Barker et
al. 2006). Expandable clays tend to react readily with lime, losing plasticity
immediately (Bell and Coulthard 1990). Lime reduces the swell-shrink potential of
Journal of Materials in Civil Engineering. Submitted October 20, 2013; accepted January 24, 2014; posted ahead of print January 27, 2014. doi:10.1061/(ASCE)MT.1943-5533.0001040
Copyright 2014 by the American Society of Civil Engineers
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expansive soils through physico-chemical modifications (Mateos 1964; Bhasin et al.
1978; Akbulut and Arasan 2010). Lime treatment on the expansive clay is a very
complicated process. Several mechanisms were proposed to explain this process.
Cation exchange is believed to be the first important reaction when adding lime to
expansive soil (Bell 1996; Prusinski and Bhattacharja 1999; Boardman et al. 2001). A
large amount of Ca2+ generated by lime dissolved in water can exchange other
cations absorbed by smectite clay. This can reduce the swelling of the smectite clay.
Flocculation and agglomeration are the second phenomena that change the
microstructure of clay. High ions concentration and high pH environment reduce the
thickness of the electrical double layer and cause the flocculation of the clay particles
(Mitchell & Soga 2005). The flocculated clay particles attach to each other and form
large clusters or blocks, which is the agglomeration (Bell 1996; Boardman et al. 2001;
Cuisinier et al. 2011; Al-Mukhtar et al. 2012). Pozzolanic reaction is considered to be
another important reaction for the lime reacting with expansive clay. Ca2+, SiO32-,
and Al2O32- from dissolved clay particles in high pH environment form calcium
silicate hydrate (CSH) and calcium aluminium silicate hydrate (CAH) (Diamong and
Kinter 1965; Boardman et al. 2001). This reaction is a long term process, contributing
to the later strength increase of the expansive clay (Bell 1996; Rao et al. 2005).
Earlier studies indicate that curing periods>7days (at room temperature) facilitate a
substantial degree of pozzolanic reactions (Prakash et al. 1989; Bell 1988a)
Ca(OH)2 and Mg(OH)2 continuously react with CO2 in the air and form stiff solid
particles with high strength such as CaCO3 and MgCO3. The crystallization reaction
Journal of Materials in Civil Engineering. Submitted October 20, 2013; accepted January 24, 2014; posted ahead of print January 27, 2014. doi:10.1061/(ASCE)MT.1943-5533.0001040
Copyright 2014 by the American Society of Civil Engineers
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of forming Ca(OH)2∙nH2O is also an important process during lime treatment of
expansive clay. Scanning electron microscope (SEM) and x-ray diffraction studies
were conducted to observe the physicochemical and cementitious reactions process
during lime treatment on soil (Wilkinson et al. 2010). SEM is also used investigate the
microstructure of lime treated expansive soils (Shi et al. 2007). This paper reported a
study conducted on lime treatment of Nanyang expansive clay. The above
mechanisms were reexamined in the study.
Nanyang Expansive Clay
Nanyang expansive clay is used in this testing program. This clay is widely
distributed in Nanyang of Henan Province, located in the central middle of China.
Nanyang expansive clay is a yellowish brown and very stiff soil. It is an alluvial
deposit formed in the mid Pleistocene epoch (Huang 1991). Table 1 lists the basic
physical properties of Nanyang expansive clay. Its residual water content is 7.28%
and specific gravity is 2.48. Its liquid limit and plastic limit are found to be 62 and 23,
respectively. A hydrometer analysis conducted on this type of clay gives an 82.7% of
clay and silt particles passing 0.075 mm sieve. The activity of this clay is 1.35. The
1D swelling test value is 4.20% according to ASTMD4546. The cation exchange
capacity of this clay is found to be 41.37 cmol/kg. X-ray diffraction analyses were
conducted using SHIMADZU XRD-6000 apparatus. X-ray diffraction pattern for
Nanyang expansive clay is shown in Fig. 1. The X-ray diffraction analyses indicate
that the major clay minerals are a mixture of illite and smectite, with some kaolinite
Journal of Materials in Civil Engineering. Submitted October 20, 2013; accepted January 24, 2014; posted ahead of print January 27, 2014. doi:10.1061/(ASCE)MT.1943-5533.0001040
Copyright 2014 by the American Society of Civil Engineers
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and chlorite.
The lime used in this study was bought from a commercial manufacturer. An X-ray
fluorescence spectrometer analysis was conducted on the lime sample using
SHIMADZU XRF-1800 device. The testing results are listed in Table 2. The testing
data indicated that CaO content is over 90%, with 3.69% of MgO. The optimum lime
content was determined through pH value according to ASTM D 6276-99a to be 3.8%
for Nanyang expansive clay.
1D Swelling and Triaxial Test of Lime Treated Nanyang Expansive Clay
In order to examine the improvement of swelling properties of lime treated Nanyang
expansive clay, one dimensional swelling test was conducted at different curing times
(immediately after compaction(0h), 1h, 4h, 24h, 7d, 28d, 90d). To prepare the
specimen, deionized water was added to the air dried soil (passing 0.5 mm sieve) to
optimum water content, mixed uniformly and then sealed in a plastic bag cured for 24
hrs in a moisture chamber at a humidity above 90% and a temperature about 23 C.
After 24 hrs, the mixture was compacted in the consolidometer ring according to the
maximum dry unit weight. It was then used for 1D swell test. For the lime treated
specimens, 3.84% dry soil mass of lime powerder will be added to the moist soil
mixture and mixed again. The lime mass added was determined by performing pH test
according to ASTM D6276. The lime-soil mixture was then compacted in the
consolidometer ring according to the maximum dry unit weight of Nanyang expansive
clay. Then, they were put into sealed plastic bags and cured in a moisture chamber
with humidity above 90% and temperature around 23 C. At the specified curing time,
Journal of Materials in Civil Engineering. Submitted October 20, 2013; accepted January 24, 2014; posted ahead of print January 27, 2014. doi:10.1061/(ASCE)MT.1943-5533.0001040
Copyright 2014 by the American Society of Civil Engineers
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they were taken out from the moisture chamber for 1D swell test. Testing results are
summarized in Table 3. It is noticed that 1D swell of Nanyang expansive clay dropped
from 4.20 %( untreated) to 3.24% (tested immediately after compaction). With curing
time continuing, 1D swell of treated specimen kept decreasing. At 28 days of curing
time, 1D swell of the treated clay is very low now, not showing noticeable swelling.
The most significant reduction in swelling happened within the first 4 hrs after
compaction for the case studied.
In order to obtain the improvement of strength properties of Nanyang clay after
lime treatment, triaxial test was conducted on the prepared specimen after 28 days
curing. The specimen preparation procedure is the same as that for 1D swell test
except that the soil specimen was compacted in a split triaxial mold. The dry unit
weight of the specimens is controlled as the maximum dry unit weight. The specimens
were sheared at the optimum water content at different confining pressures. Fig. 2 and
Fig. 3 showed the triaxial test results of Nanyang clay before and after lime treatment,
respectively. It was seen from the triaxial test results that the stress-strain curve of
natural Nanyang clay is softened at low confining pressure(less than 200 kPa).
However, the stress-strain curve of lime treated Nanyang clay is stiffer compared to
the untreated specimen. The friction angle and cohesion for the untreated Nanyang
clay are 12.5 and 86.7kPa, respectively. The friction angle and cohesion for the lime
treated Nanyang clay are 14.9 and 95.1kPa, which increases slightly.
SEM Analyses
To observe the microstructure change and reaction of lime and Nanyang expansive
Journal of Materials in Civil Engineering. Submitted October 20, 2013; accepted January 24, 2014; posted ahead of print January 27, 2014. doi:10.1061/(ASCE)MT.1943-5533.0001040
Copyright 2014 by the American Society of Civil Engineers
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clay, a series of SEM (scanning electronic microscopy) analyses were conducted. The
specimen preparation is the similar as that for 1D swell test triaxial test except that
the specimen was compacted according to the standard proctor compaction method
(ASTM D698-12) in a compaction mold. After compaction, the 4-inch diameter
specimen was sealed in a plastic bag and cured in the moisture chamber at a humidity
above 90% and a temperature about 23 C. At the specified curing time, a small block
of soil mass was taken from the compaction sample and air dried for SEM testing.
The SEM micrograph on natural Nanyang expansive clay is shown in Fig. 4(a). Some
clay particles have a flat thin surface which is a feature of semctite. Other particles
have a fibrous structure at the edge, which is a feature of illite. SEM image indicated
that major clay minerals in Nanyang expansive clay are a mixture of illite and
smectite with some kaolinite (Fig. 4 (a)), which is consistent with the testing results of
X-ray diffraction analysis.
The microstructure of lime treated Nanyang expansive clay compacted without curing
is shown in Fig. 4(b). It is clear that the original microstructure of clay was destroyed.
The large particles were broken into many small particles. The small particles were
agglomerated together. There formed polygonal shaped crystal sheets in the clay
matrix, which are Ca(OH)2.nH2O crystals.
The SEM micrograph of lime treated Nanyang expansive clay at 4 hrs curing after
compaction is shown in Fig. 5(a). It is clear that the clay particles were further broken
into smaller sized particles. We can see the eroded edges of the original clay particles.
Journal of Materials in Civil Engineering. Submitted October 20, 2013; accepted January 24, 2014; posted ahead of print January 27, 2014. doi:10.1061/(ASCE)MT.1943-5533.0001040
Copyright 2014 by the American Society of Civil Engineers
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Ca(OH)2.nH2O crystals were also observed in the SEM images. At 24 hrs curing time
after compaction, SEM image for the lime treated Nanyang expansive clay is shown
in Fig. 5(b). This image indicates that the reaction was continuing and the clay
particles were further eroded by lime.
Fig. 6 (a) is the SEM micrograph for lime treated Nanyang expansive clay at 7 days
curing time after compaction. In this image, we almost cannot recognize the original
structure of clay. There are large flat polygonal thick sheets formed from small to
large size. This structure formation is possibly due to not well-crystallized
Ca(OH)2•2H2O particles. Many single of them linked together to form the large sheet
structure. However, this structure is only locally distributed in the whole clay
specimen because of the non-uniform distribution of lime and water available
surrounding clay particles. This micro morphology for the lime treated expansive clay
was rarely observed by previous researchers. Fig. 6(b) was the SEM image of lime
treated Nanyang expansive clay at 28 days curing time after compaction. This image
displays the severely broken structure of Nanyang expansive clay after lime treatment.
Comparing with the microstructures obtained at earlier time, the particle size was
larger, indicating that the more small particles agglomerate together with increasing
curing time.
Fig. 7 is the SEM micrograph of lime treated expansive clay at 90 days curing time
after compaction. From this image, we can observe the polygonal sheet structure,
broken clay particles, and the fibrous structure in the treated clay. The fibrous
structure indicated that there are Ca(OH)2.nH2O and pozzolanic reaction products
Journal of Materials in Civil Engineering. Submitted October 20, 2013; accepted January 24, 2014; posted ahead of print January 27, 2014. doi:10.1061/(ASCE)MT.1943-5533.0001040
Copyright 2014 by the American Society of Civil Engineers
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(CAH and CSH) in the late curing period for lime treated Nanyang expansive clay.
Quantitative Analyses of Ca2+ and K+
Once lime was mixing with the clay, it firstly dissolved in the soil pore water and
further Ca2+ reacted with cations in the clay. In order to analyze the mechanism of
cations reaction during the lime treatment of the expansive clay, a series of chemical
tests were conducted on the lime treated Nanyang expansive clay at different curing
time after lime treatment. The concentration of Ca2+ and K+ in the soil pore water
and in the exchange complex of clay was examined, respectively.
The sample preparing procedure was the same as that for SEM analyses. Using the
same compacted sample, after different curing time, a soil mass was obtained for the
chemical analyses. It was then air dried quickly with a wind dryer and broken into
particles with size less than 0.075 mm. The pore water extraction was conducted
according to the following steps: 1) A 25 g of air dried soil was put into a clean 200
ml plastic centrifuge bottle; 2) A 100 ml of deionized water was added into the bottle;
3) The bottle was placed on a high speed shaker for 15 minutes and the bottle was
centrifuged for 15 minutes at 2500 revolution per minutes (rpm); 4) The supernatant
from the sample was removed with a pipette and was placed into a clean
polypropylene bottle. 0.5% of concentrated nitric acid was added into the bottle to
lower the pH to less than 2.0. After the extraction, major cations’ concentration in the
extracted solutions was tested using an atomic absorption spectrometer (Solaar969).
Fig. 8 shows that after adding lime (curing for one day), the concentration of Ca2+
Journal of Materials in Civil Engineering. Submitted October 20, 2013; accepted January 24, 2014; posted ahead of print January 27, 2014. doi:10.1061/(ASCE)MT.1943-5533.0001040
Copyright 2014 by the American Society of Civil Engineers
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increased from 198.7 meq/L to 326.3 meq/L. This increase was due to free Ca2+
released by the lime dissolved in the soil pore water. This is ions crowding
phenomenon as observed by previous studies (Osula 1991; Little 1995). The
dissolution of lime in the soil pore water finished rather quickly within 24 hrs. At 7
days, we did not observe any significant increase of the concentration for Ca2+ in the
soil pore water. The concentration of Ca2+ tested after 28 day and 90 day curings
decreased significantly as shown in Fig. 8. This indicated that there was a great
consumption of Ca2+ during this period. One possible consumption source is the
pozzolanic reaction. After 90 days curing, there were the pozzolanic reaction products
observed in SEM studies, which also consumed Ca2+ in the pore water. The
formation of CaCO3 was also possible after a long curing period. This is another
consuming source of Ca2+ in the pore water.
The same chemical analyses were done on K+ in the soil pore water. Testing results
are summarized in Fig. 9. Immediately after compaction, concentration of K+ slightly
decreased in the pore water. A significant increase in the concentration of K+ tested at
7 days of curing was observed. Then, the concentration of K+ started to reduce after 7
days of curing. The concentration of K+ was reduced to 0.05 and 0.04 meq/L at
curing time of 28 days and 90 days, respectively. The first increase of concentration
for K+ is due to the cation exchange by Ca2+. The reduction of K+ is possibly due to
formation of K2SiO3 with SiO32- by the clay particles dissolved in the high pH
environment or other low soluble potassium compounds.
In order to further examine the cations change phenomena in Nanyang expansive clay,
Journal of Materials in Civil Engineering. Submitted October 20, 2013; accepted January 24, 2014; posted ahead of print January 27, 2014. doi:10.1061/(ASCE)MT.1943-5533.0001040
Copyright 2014 by the American Society of Civil Engineers
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the Ca2+ concentration in the exchange complex of clay was also investigated.
Cations in the exchange complex of Nanyang expansive clay were extracted as
follows:
1) Prepare a solution of ammonium acetate by placing 77.1 g of crystal ammonium
acetate in a container and bring the volume up to one liter with deionized water; 2)
Put 4 g of air dried soil (passing 0.075 mm sieve) into a 50 ml clean plastic centrifuge
bottle; 3) Add 33 ml of the ammonium acetate solution and shake until no dry soil
seen at the bottom; 4) Place the bottle on a high speed shaker for 15 minutes, and
centrifuge the mixture at 2500 rpm for 15 minutes; 5) Remove the supernatant with a
pipette; 6) Repeat step 2 through 5, two more times on the same soil sample; and 7)
Place all collected supernatant in a clean polypropylene bottle and add 0.5%
concentrated nitric acid, lowering the pH to below 2.0.
After this extraction was completed, the concentration of Cations was measured using
atomic absorption (AA ) method. The testing data for the concentration of Ca2+ was
shown in Fig. 10. The concentration of Ca2+ in the exchange complex of clay
increased from 230 meq/100g before treated by Lime to 280 meq/100g after treated
with Lime immediately after compaction. This indicated a strong cations exchange
reaction happened between Ca2+ in the pore water and other cations in the exchange
complex of clay. This reaction continued to 28 days curing time after compaction. The
Ca2+ concentration in the exchange complex keeps increasing to 28 days. The
concentration of Ca2+ tested at 90 days decreased greatly. This decrease was due to
the broken of clay particles in the high pH environment and the pozzolanic reaction
Journal of Materials in Civil Engineering. Submitted October 20, 2013; accepted January 24, 2014; posted ahead of print January 27, 2014. doi:10.1061/(ASCE)MT.1943-5533.0001040
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happened in the lime treated expansive clay.
To examine the behavior of other cations during the lime treatment, a series of
chemical analyses were also conducted on K+ in the exchange complex of Nanyang
expansive clay. Testing results are summarized in Fig. 9.
As illustrated in Fig. 11, immediately after compaction, the concentration of K+
increased greatly. This increase was due to the exchange reaction between K+ in the
pore water and other cations (Ca2+, Na+ etc.) in the exchange complex of clay. 7 days
after curing, the concentration of K+ in the exchange complex of clay decreased
greatly. The concentrations of K+ tested in the pore water and in the exchange
complex of the clay decreased. This sounds contradictory. This was possibly because
there are many more complex reactions ongoing during lime treatment on the clay.
After long curing time, part of the K+ in the exchange complex of clay might not be
extracted in the AA testing. Some clay particles may be bound by carbonation
products and pozzolanic products. Further research needs to explore into this topic.
Discussions
This first step change in the microstructure of Nanyang expansive clay by lime
reflected in Fig. 2 (b). The clay structure became more flocculated and granulated
which reduced its contacting surface with water, which caused the reduction of its
swelling potential. This observed flocculation and agglomeration was also noticed by
other investigations (Bell 1996; Boardman et al 2001; Cuisinier et al 2011;
Al-Mukhtar et al 2012) .This was observed immediately after compaction after
mellowing lime and moist soil for 24 hrs. Meanwhile, as seen from Fig. 8 through Fig.
Journal of Materials in Civil Engineering. Submitted October 20, 2013; accepted January 24, 2014; posted ahead of print January 27, 2014. doi:10.1061/(ASCE)MT.1943-5533.0001040
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11, the concentration of Ca2+ increased in the pore water, which further depresses the
double layer’s thickness of clay particles; the concentration of Ca2+ and K+ increased
in the exchange complex of clay, which further draws clay particles more firmly
together. The swelling potential of clay also decreases with the depressed double layer
and the firmly connected clay particles. These changes in microstructure and chemical
properties caused the decrease of 1D swelling value (from 4.20% to 3.24%). This
initial and immediate change caused by cation exchange was also point out by other
researchers (Bell 1996; Bell and Coulthard 1990; Boardman et al. 2001; Al-Mukhtar
et al 2012). At curing time of 4 hrs, the further broken down of the clay particles by
lime caused a more coarse structure, which further reduced 1D vertical swelling to
0.11%. While at 24 hrs of curing, the microstructure of clay showed no significant
difference from that of at 4 hrs, which only caused a slight reduction of 1D swelling.
Most of the effect of reducing swelling of the clay by lime finished in the first 7 days
as observed from this study. The flocculated and coarse microstructure of lime treated
Nanyang clay increases its friction angle; the formation of Ca(OH)2.nH2O and other
cohesive products (from lime-soil pozzolanic reaction) made the lime treated clay
increasing its cohesion. These were proved with the triaxial testing results (Fig. 2 and
Fig. 3). The SEM image of treated clay at 90 days of curing (Fig. 7) indicates that the
pozzolanic reaction is more significant. The concentration drop of Ca2+ and K+ also
supported this conclusion. The observation of pozzolanic products at 90 days curing
contributed to the later strength of lime treated clay, which was also pointed out by
previous studies (Bell 1996; Boardman et al. 2001). The lime-clay reaction can be
Journal of Materials in Civil Engineering. Submitted October 20, 2013; accepted January 24, 2014; posted ahead of print January 27, 2014. doi:10.1061/(ASCE)MT.1943-5533.0001040
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described as a progressive dissolution of large clay particles followed by formation of
CSH and CAH (Al-Mukhtar et al 2012). The increase of friction angle and cohesion
at 28 days were not very significant for Nanyang clay can also be explained by few
pozzolanic products observed in the SEM testing (Fig. 6(b)).
Conclusions
Lime generally improves the engineering properties of soils. The mechanism of lime
on expansive clay was reexamined in this paper through testing on Nanyang
expansive clay. Through SEM analyses and AA cations analyses, the following
conclusions are drawn.
The major clay minerals of Nanyang expansive clay is mixture of illite and smectite,
kaolinite and chlorite. It is a type of medium expansive clay.
At early stage of lime treatment, cations crowding happened in the soil pore water as
indicated by the rise of Ca2+ and K+ in the soil pore water. There was a formation of
Ca(OH)2. nH2O crystals in the treatment as shown in SEM results. Cation exchange
also happened during the early stage of lime treatment. Cations crowding and high pH
environment caused flocculation and agglomeration of clay particles. These reactions
happened rather quickly. Most of reactions finished within one week for this study.
These early reactions caused most of the reduction of swelling for the tested clay
within one week after lime treatment. Thus, the dominant reactions are cations
crowding, cation exchange, formation of Ca (OH)2. nH2O crystals, broken of clay
particles in high pH environment, and agglomeration. There was an increase of
friction angle and cohesion for the lime treated Nanyang expansive clay after curing
Journal of Materials in Civil Engineering. Submitted October 20, 2013; accepted January 24, 2014; posted ahead of print January 27, 2014. doi:10.1061/(ASCE)MT.1943-5533.0001040
Copyright 2014 by the American Society of Civil Engineers
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for 28 days. Pozzolanic reaction happened more significantly at late stage during lime
treatment (90 days in this study). Carbonation also possibly happened at late stage of
lime treatment.
The lime treated Nanyang expansive clay is a mixture of many different materials at
late stage, such as unreacted clay particles, Ca(OH)2. nH2O crystals, CSH and CAH,
carbonation products etc. The great decrease of Ca2+ and K+ in both pore water and
exchange complex of clay at late stage of lime treatment needs more researches to
explore this phenomenon.
Acknowledgement
The financial support of National Natural Science Foundation of China (No.
51308091) is greatly appreciated. This research is part of the National Key
Technology R&D Program in the 12th Five-Year Plan of China (No. 2011BAB10B05)
Additionally, the project is also sponsored by SRF for ROCS, SEM.
References
Akbulut, A., Arasan, S. (2010). “The variations of cation exchange capacity, pH, and
Zeta potential in expansive soils treated by additives.” International Journal of Civil
and Structural Engineering, 1(2), 139-154.
Al-Mukhtar, M., Khattab, S., Alcover, J.-F. (2012). “Microstructure and geotechnical
properties of lime-treated expansive clayey soil.” Engineering Geology, 139-140,
17-27.
Journal of Materials in Civil Engineering. Submitted October 20, 2013; accepted January 24, 2014; posted ahead of print January 27, 2014. doi:10.1061/(ASCE)MT.1943-5533.0001040
Copyright 2014 by the American Society of Civil Engineers
J. Mater. Civ. Eng.
Dow
nloa
ded
from
asc
elib
rary
.org
by
SOU
TH
ER
N C
AL
IFO
RN
IA U
NIV
ER
SIT
Y o
n 04
/06/
14. C
opyr
ight
ASC
E. F
or p
erso
nal u
se o
nly;
all
righ
ts r
eser
ved.
Accep
ted M
anus
cript
Not Cop
yedit
ed
16
16
ASTM. (2006). “Standard test method for using pH to estimate the soil-lime
proportion requirement for soil stabilization. ” D6276-99a West Conshohocken, PA.
ASTM. (2008). “Standard test methods for one-dimensional swell for collapse of
cohesive soils.” D4546-08 West Conshohocken, PA.
ASTM.(2010). “Standard test method for measuring the exchange complex and cation
exchange capacity of inorganic fine-grained soils.” D7503-10 West Conshohocken,
PA.
Barker, J. E., Rogers, C. D. F., and Boardman, D. I. (2006). “Physiochemical changes
in clay caused by ion migration from lime piles.” J. Mater. Civ. Eng., 18(2), 182-189.
Bell, F. G. (1988a). “Stabilization and treatment of clay soils with lime, Part 1-Basic
principles.” Ground Eng., 21(1), 10-15.
Bell, F. G. (1988b). “Stabilization and treatment of clay soils with lime. Part 2: Some
applications.” Ground Eng., 21(2), 22-30.
Bell, F. G. (1996). “Lime stabilization of clay minerals and soils.” Eng. Geol., 42(4),
223-237.
Bell, F.G., Coulthard, J. M. (1990). “Stabilization of clay soils with lime.” Mun. Engr.,
7:125-140.
Bhasin, N. K., Dhawan, P. K., and Mehta, H. S. (1978). “Lime requirement in soil
stabilization.” Bulletin No. 7, Highway Research Board, Washington, DC, 15-26.
Boardman, D. I., Glendinning, S. & Rogers, C. D. F. (2001). “Development of
stabilisation and solidification in lime-clay mixes.” Geotechnique, 50(6), 533-543.
Chaddock, B. C. J. (1996). “The structural performance of stabilised soil in road
Journal of Materials in Civil Engineering. Submitted October 20, 2013; accepted January 24, 2014; posted ahead of print January 27, 2014. doi:10.1061/(ASCE)MT.1943-5533.0001040
Copyright 2014 by the American Society of Civil Engineers
J. Mater. Civ. Eng.
Dow
nloa
ded
from
asc
elib
rary
.org
by
SOU
TH
ER
N C
AL
IFO
RN
IA U
NIV
ER
SIT
Y o
n 04
/06/
14. C
opyr
ight
ASC
E. F
or p
erso
nal u
se o
nly;
all
righ
ts r
eser
ved.
Accep
ted M
anus
cript
Not Cop
yedit
ed
17
17
foundations.” In Lime stabilization (eds C. D. F. Rogers, S. Glendinning and N.
Dixon), 75-94. London: Thomas Telford.
Consoli, N. C., Lopes, L. S. Jr., Prietto, P. D. M., Festugato, L., Cruz, R. C. (2011).
“Variables controlling stiffness and strength of limestabilized soils.” J. Geotech.
Geoenviron. Eng., 137(6), 628-632.
Cuisinier, O., Auriol, J.-C., Borgne, L. T., Deneele, D. (2011). “Microstructure and
hydraulic conductivity of a compacted lime-treated soil.” Engineering Geology, 123,
187-193.
Dash, S. K., Hussain, M. (2012). “Lime stabilization of soils: Reappraisal.” J. Mater.
Civ. Eng., 24(6), 707–714.
Diamond, S., Kinter, E. B. (1965). “Mechanisms of soil-lime stabilization”. Highway
Research Record, No. 92, 83-102.
Herrin, M., Mitchell, H. (1961). “Lime-soil mixtures.” Bulletin No. 304, Highway
Research Board, Washington, DC, 99-138.
Huang, G.-S. (1991). “Engineering geology of expansive soil in Pingding Mountain
and Nanyang basin.” J. Site Investigation Science and Technology, 6, 39-41.
Khattab, S. A. A., Al-Mukhtar, M., and Fleureau, J. M. (2007). “Long-term stability
characteristics of a lime-treated plastic soil.” J. Mater. Civ. Eng., 19(4), 358-366.
Little, D. N. (1995). Handbook for stabilization of pavement subgrades and base
courses with lime. Lime Association of Texas, USA.
Mateos, M. (1964). “Soil-lime research at Iowa State University.” J. Soil Mech.and
Found. Div., 90(2), 127-153.
Journal of Materials in Civil Engineering. Submitted October 20, 2013; accepted January 24, 2014; posted ahead of print January 27, 2014. doi:10.1061/(ASCE)MT.1943-5533.0001040
Copyright 2014 by the American Society of Civil Engineers
J. Mater. Civ. Eng.
Dow
nloa
ded
from
asc
elib
rary
.org
by
SOU
TH
ER
N C
AL
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RN
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NIV
ER
SIT
Y o
n 04
/06/
14. C
opyr
ight
ASC
E. F
or p
erso
nal u
se o
nly;
all
righ
ts r
eser
ved.
Accep
ted M
anus
cript
Not Cop
yedit
ed
18
18
Mitchell, K. J., Soga, K. (2005). Fundamentals of soil behavior, John Wiley & Sons,
Inc. Hoboken, New Jersey.
Osula, O.A.D. (1991). “Lime modification of problem laterite.” Engineering Geology,
30(2), 141-154.
Prakash, K., Sridharan, A., and Rao, S. M. (1989). “Lime addition and curing effects
on the index and compaction characteristics of a montmorillonitic soil.” Geotech.
Eng., 20(1), 39-47.
Prusinski, J., and Bhattacharja, S. (1999). “Effectiveness of Portland Cement and
Lime in stabilizing clay soils”. Transportation Research Record, 1652, 215-227.
Rajasekaran, G., and Rao, S. N. (2000). “Strength characteristics of lime-treated
marine clay.” Proc. Inst. Civ. Eng. Ground Improv., 4(3), 127-136.
Rao, M.S., Shivananda, P. (2005). “Role of curing temperature in progress of
lime-soil reactions”. Geotechnical and Geological Engineering, 23, 79-85.
Rao, S. M., and Thyagaraj, T. (2003). “Lime slurry stabilization of an expansive soil.”
Geotech. Eng., 156(3), 139-146.
Rogers, C. D. F., Glendinning, S., and Holt, C. C. (2000). “Slope stabilization using
lime piles: A case study.” Ground Improv., 4(4), 165-176.
Shi, B., Liu, Z., Cai, Y., Zhang, X. (2007). “Micropore structure of aggregates in
treated soils.” J. Mater. Civ. Eng., 19(1), 99-104.
Thyagaraj, T., Rao, M. S., Suresh, P. S., Salini, U. (2012). “ Laboratory studies on
stabilization of an expansive soil by Lime precipitation technique.” J. Mater. Civ.
Eng., 24(8), 1067-1075.
Journal of Materials in Civil Engineering. Submitted October 20, 2013; accepted January 24, 2014; posted ahead of print January 27, 2014. doi:10.1061/(ASCE)MT.1943-5533.0001040
Copyright 2014 by the American Society of Civil Engineers
J. Mater. Civ. Eng.
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Y o
n 04
/06/
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ight
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or p
erso
nal u
se o
nly;
all
righ
ts r
eser
ved.
Accep
ted M
anus
cript
Not Cop
yedit
ed
19
19
Toohey, N. M., Mooney, A. M., Bearce, R. G. (2013). “Stress-strain-strength
behavior of Lime-stabilized soil during accelerated curing.” J. Mater. Civ. Eng.,
25(12), 1880-1886.
Wilkinson, A., Haque, A., Kodikara, J., Adamson, J., and Christie, D. (2010).
“Improvement of problematic soils by lime slurry pressure injection: case study”. J.
Geotech. Geoenviron. Eng., 136(10), 1459-1468.
Journal of Materials in Civil Engineering. Submitted October 20, 2013; accepted January 24, 2014; posted ahead of print January 27, 2014. doi:10.1061/(ASCE)MT.1943-5533.0001040
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Fig. 1 X-ray diffraction pattern of Nanyang expansive clay
Fig. 2 Stress-strain curves of untreated Nanyang clay
Fig. 3 Stress-strain curves of Lime treated Nanyang clay
Fig. 4 (a) SEM image of compacted Nanyang expansive clay; (b) SEM image of lime
treated Nanyang expansive clay immediately after compaction
Fig. 5 SEM image of lime treated Nanyang expansive clay after compaction (a) at 4
hrs curing time, (b) at 24 hrs curing
Fig. 6 SEM image of lime treated Nanyang expansive clay after compaction (a) at 7
days curing time, (b) at 28 days curing time
Fig. 7 SEM image of lime treated Nanyang expansive clay at 90 days curing time
after compaction
Fig. 8 Concentration of Ca2+ in soil pore water
Fig. 9 Concentration of K+ in soil pore water
Fig. 10 Concentration of Ca2+ in exchange complex of Nanyang expansive clay
Fig. 11 Concentration of K+ in exchange complex of Nanyang expansive clay
Journal of Materials in Civil Engineering. Submitted October 20, 2013; accepted January 24, 2014; posted ahead of print January 27, 2014. doi:10.1061/(ASCE)MT.1943-5533.0001040
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Journal of Materials in Civil Engineering. Submitted October 20, 2013; accepted January 24, 2014; posted ahead of print January 27, 2014. doi:10.1061/(ASCE)MT.1943-5533.0001040
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Journal of Materials in Civil Engineering. Submitted October 20, 2013; accepted January 24, 2014; posted ahead of print January 27, 2014. doi:10.1061/(ASCE)MT.1943-5533.0001040
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Journal of Materials in Civil Engineering. Submitted October 20, 2013; accepted January 24, 2014; posted ahead of print January 27, 2014. doi:10.1061/(ASCE)MT.1943-5533.0001040
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Table 1 Basic Physical Properties of Nanyang Expansive Clay
w r
(%)Gs PL LL PI
w opt
(%)dmax
(kN/m3)
1D Swell
%
Activity(PI/Clay%
<0.002mm)
7.27 2.48 23 62 39 25.0 15.3 4.20 1.35
Accepted Manuscript Not Copyedited
Journal of Materials in Civil Engineering. Submitted October 20, 2013; accepted January 24, 2014; posted ahead of print January 27, 2014. doi:10.1061/(ASCE)MT.1943-5533.0001040
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Table 2 X-ray fluorescence spectrometer analysis on Lime
Oxide CaO MgO SiO2 Al2O3 Fe2O3 SO3 K2O TiO2 SrO other
% 91.35 3.69 2.70 0.74 0.66 0.53 0.15 0.11 0.06 0.02
Accepted Manuscript Not Copyedited
Journal of Materials in Civil Engineering. Submitted October 20, 2013; accepted January 24, 2014; posted ahead of print January 27, 2014. doi:10.1061/(ASCE)MT.1943-5533.0001040
Copyright 2014 by the American Society of Civil Engineers
J. Mater. Civ. Eng.
Dow
nloa
ded
from
asc
elib
rary
.org
by
SOU
TH
ER
N C
AL
IFO
RN
IA U
NIV
ER
SIT
Y o
n 04
/06/
14. C
opyr
ight
ASC
E. F
or p
erso
nal u
se o
nly;
all
righ
ts r
eser
ved.
Table 3 1D swell of lime treated Nanyang expansive clay at different curing times
Curing time 0 hr 1 hr 4 hrs 24hrs 7 days 28 days 90 days
Lime treatedNanyang clay
3.24 3.09 0.11 0.09 0.06 0.005 0.004
Accepted Manuscript Not Copyedited
Journal of Materials in Civil Engineering. Submitted October 20, 2013; accepted January 24, 2014; posted ahead of print January 27, 2014. doi:10.1061/(ASCE)MT.1943-5533.0001040
Copyright 2014 by the American Society of Civil Engineers
J. Mater. Civ. Eng.
Dow
nloa
ded
from
asc
elib
rary
.org
by
SOU
TH
ER
N C
AL
IFO
RN
IA U
NIV
ER
SIT
Y o
n 04
/06/
14. C
opyr
ight
ASC
E. F
or p
erso
nal u
se o
nly;
all
righ
ts r
eser
ved.
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