Showing papers on "Soil stabilization published in 2015"

Stabilization of clayey soil using ultrafine palm oil fuel ash (POFA) and cement

Abstract: Palm oil fuel ash (POFA) in both cost-effective and environmentally friendly ways has potential applications in soft soil stabilization. This study investigates the possible uses of POFA (individually and in combination with cement) on several basic characteristics of clayey soil behavior, such as proctor compaction, Atterberg limit, and unconfined compression strength (UCS). These properties are compared with those of unstabilized clay and stabilized clay with cement. Scanning electron microscopy with X-ray microanalysis is conducted on untreated and treated soil to elucidate their strength development, and the observed test results are then explained. Findings show that POFA and POFA/cement mixture treatments result in significant reductions in the soil plasticity index (PI). The results of the compaction test indicate that the utilization of POFA and POFA/cement mixture in soft soil stabilization decreases the optimum moisture content and increases the maximum dry density across selected binder dosages. The results show that using POFA alone to stabilize clayey soil results in a slight increase in the UCS of the specimens until the 28 days of curing, whereas combining POFA with cement results in a sharp increase in the UCS of the samples in the same curing time. The results demonstrate the environmental, technological, and economic advantages of utilizing this well known agricultural waste as a partial substitute for cement in stabilizing soils, particularly soft soils that usually demand high quantities of stabilizer to reach satisfactory results.

Alkali-Activated Ground-Granulated Blast Furnace Slag for Stabilization of Marine Soft Clay

Abstract: This paper investigated the stabilization efficacy of alkali-activated ground-granulated blast furnace slag (GGBS) for a marine soft clay, compared with that of portland cement (PC). The influence of activators, including NaOH, Na2CO3, carbide slag (CS), NaOH-CS, Na2CO3-CS, and Na2SO4-CS, on the stabilization efficacy was investigated. A range of tests were conducted to investigate the properties of stabilized clays, including unconfined compressive strength (UCS), X-ray diffraction (XRD), scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP). The results indicated that Na2CO3-GGBS had no stabilization efficacy for this marine soft clay. NaOH-GGBS-stabilized clay yielded the highest UCS at 7, 28, and 90 days; however, the UCS decreased from 90 to 180 days because of the microcracking. CS-GGBS-stabilized clay had higher 90-day and 180-day UCS than that of PC-stabilized clay, but significantly lower 7-day and 28-day UCS. NaOH, Na2CO3, and Na2SO4 could enhance the strength devel...

Experimental study on stabilization of a low plasticity clayey soil with cement/lime

Abstract: One of the possible problems that may be encountered by execution of future projects such as highway, mass construction, and also industrial buildings in Farmahin (in the northwestern of Arak, Iran) is low strength and large deformation of the field soil. Such soils can be treated with the general traditional soil stabilization methods such as lime or cement stabilization methods. In the current study, the effects of two types of additive for the soil (i.e., lime/cement) on the geotechnical and engineering properties of the soil are studied. The results of the study indicate that optimum moisture content, maximum dry unit weight, and plasticity index are affected by the addition of cement or lime. Also cement treatment results in increase of unconfined compressive strength (UCS) of the soils significantly, whereas the test results indicate that there is an optimum of lime content so that the addition of a few percentage of lime results in increase of unconfined compressive strength. Generally, improvement in mechanical behaviors of the soil due to cement treatment was noticeably higher than lime treatment. Also the results of tests show that the change of UCS of the specimens with the initial water content and curing time is significant, so that decreasing of initial water content or increasing of curing time results in increase of USC of the specimens. Also, the current study sought to characterize the relationship between secant modulus (E50) and UCS, curing time, and cement or lime content.

Environmentally appraising different pavement and construction scenarios: A comparative analysis for a typical local road

Abstract: The aim of this work is to carry out a comparative analysis of environmental impacts for different scenarios of a typical local road. Life Cycle Assessment (LCA) is the modeling tool used to quantify and characterize comparative environmental impacts. In carrying out this specific application of the LCA, different road construction techniques were considered with regards to the whole structure and compared in order to identify the best alternative in terms of environmental sustainability. So far, in fact, typical LCA frameworks of roads have focused on recycled materials for pavement layers only, thus neglecting study of the materials used in the embankment or in the subgrade. In this study, these materials were included too, in order to prove the environmental benefit of using a sustainable technique such as in situ stabilization of fine soils with lime (typically dumped clayey soils) in order to reduce the need for virgin material for embankment and subgrade construction. When using different percentages of recycled materials (such as reclaimed asphalt pavement – RAP) in the bituminous layer or in the foundation, the analysis of the functional unit studied shows a significant reduction of energy consumption and pollutant emissions mainly due to transportation of materials involved, in this way increasing the environmental performance of the road. Another important consideration is that the use of fine soils stabilized with lime “in situ”, instead of dumping it, not only is a good technical solution for improving soil mechanical properties, but it also produces a reduction of energy consumption and of pollutant emissions. It is noticeable that this technique results in a significant reduction of pollutant emissions due the transportation of involved materials, increasing the environmental performance of the road.

Chemically Stabilized Soft Clays for Road-Base Construction

Abstract: Soft clays are widely distributed in Missouri, United States. Due to their relatively low strength and high compressibility, subgrade construction in soft clays has encountered many difficulties. In recent practice, the use of fly ash (FA) along with lime to tackle soft subgrade problems has shown promising results. The effectiveness of Class C FA and lime kiln dust (LKD) in clay subgrade stabilization is examined in this research. Scanning electron microscopic (SEM) analysis, proctor compaction tests, unconfined compression tests, and resilient modulus tests were carried out on the FA and LKD modified soil mixtures. Test specimens were prepared at optimum water content and tested at various curing periods. The test specimens were reconstituted by static compression. Test results revealed that the addition of Class C FA could increase the dry unit weight of the FA treated soil, enhance the unconfined compressive strength, and improve the resilient modulus. Regression equations were developed to co...

A Critical Appraisal of the Role of Clay Mineralogy in Lime Stabilization

Abstract: The stabilization of problematic fine-grained soils using lime as an admixture is a widely accepted practice, owing to its simplicity and cost-effectiveness. The optimal quantity of lime required for soil stabilization primarily depends upon the reactive nature of soil as well as the degree of improvement desired. The term ‘optimum lime content’ (OLC) defines the amount of lime required for satisfying the immediate/short-term soil–lime interaction, and still providing sufficient amount of free calcium and high residual pH necessary to initiate long-term pozzolanic reaction. Previous researchers proposed various empirical correlations and experimental methodologies for determining OLC, in terms of clay-size fraction and plasticity characteristics of virgin soil. However, the limiting lime content obtained using various conventional methods does not account for the most influencing inherent clay mineralogy of the soil; and hence, the results of these methodologies are observed to be quite disagreeing with each other. In view of these discrepancies, the present study attempts to validate the existing conventional methodologies for OLC determination at an elementary level, by comprehending the fundamental chemistry following soil–lime interactions. Based on the theoretical and experimental observations, it is quite evident that the accuracy of conventional tests is limited by combined influence of chemical and mineralogical properties of soils. Hence, it is proposed to develop a precise methodology to ascertain the required optimal lime dosage based on scientific criteria, by incorporating the influence of soil properties such as clay mineralogy, specific surface area, soil pH, cation exchange capacity, soil acidity, base saturation capacity, and buffer capacity.

Evaluation of Lateritic Soil Stabilized with Arecanut Coir for Low Volume Pavements

Abstract: Soil stabilization is a common method used by engineers and designers to enhance the properties of soil with different stabilizers. From ancient times, usage of natural fiber in soil as reinforcement is an effective technology adopted. This paper presents the effect of including randomly spaced Arecanut coir to the soil mix. The engineering properties and bearing capacity of a soil get enhanced by stabilizing it with Arecanut coir and a binding material (cement). The information available on experiments and research on the behavior of soil cement mixtures were collected and a few studies conducted on fiber reinforcement were referred. The current study mainly focuses on the durability test and physical evaluation of soil cement mixtures reinforced with Arecanut coir. Coir content was varied from 0.2% to 1% with an increment of 0.2%. For further improvement, a uniform dosage of 3% cement was added to soil. Laboratory tests including the Unconfined Compressive Strength (UCS), California Bearing Ratio (CBR), durability and fatigue behavior, were conducted as per standards. The test results indicated that the improvement in characteristics of the soil cement coir mixtures were functions of coir dosage, soil type and curing days. Durability test satisfied at 1% Arecanut coir with 3% cement. The stress–strain values were determined and damage analysis was conducted for the higher dosage of Arecanut coir using KENPAVE software. From the results it is observed that, the Arecanut coir reinforced cement soil mix can be used for low volume roads (traffic ⩽1 million standard axles) and few design cases have been discussed.

On the mechanical behaviour of dredged submarine clayey sediments stabilized with lime or cement

Abstract: This paper presents the preliminary results of experimental research into the stabilization of clayey sediments dredged from the Port of Taranto (Italy) with cement and (or) lime. First, the physical properties of the natural sediments are briefly described and compared with those of the same sediments when treated with different additives and cured up to 4 years. In particular, the effect of the treatment on the soil plasticity properties is originally analyzed in terms of plasticity paths. Then, the influence of the different stabilizing agents on the compression behaviour of the dredged soil is analyzed and methods for quickly predicting the admixed-soil behaviour are presented.

Bearing Capacity of a Group of Stone Columns in Soft Soil

Abstract: Installation of stone column is a viable, cost effective, and environmentally friendly ground-improvement technique. Columns are made of compacted aggregate and are installed in weak soil as reinforcements to increase the shear resistance of the soil mass and, accordingly, its bearing capacity. While a single stone column mostly fails by bulging, a group of stone columns together with the surrounding soil may fail by general, local, or punching shear mechanism, depending on the soil/columns/geometry of the system. The mode of failure of the reinforced ground could be identified based on the ground geometry and strength parameters of both stone column and soft soil. This paper presents an analytical model to predict the bearing capacity of soft soil reinforced with stone columns under rigid raft foundation subject to general shear-failure mechanism. The model utilizes limit-equilibrium method and the concept of composite properties of reinforced soil. The proposed theory was validated for the case of bearing capacity of footings on homogenous soil and via the laboratory and numerical results available in the literature for this case. Design procedure and charts are presented for practicing purposes.

Stabilization of Expansive Soils Using Fly Ash

Abstract: Nearly 51.8 million hectares of land area in India are covered with Expansive soil (mainly Black Cotton soil). The property of these expansive soils, in general, is that they are very hard when in dry state, but they lose all of their strength when in wet state. In light of this property of expansive soils, these soils pose problems worldwide that serve as challenge to overcome for the Geotechnical engineers. One of the most important aspects for construction purposes is soil stabilization, which is used widely in foundation and road pavement constructions; this is because such a stabilization regime improves engineering properties of the soil, such as volume stability, strength and durability. In this process, removal or replacing of the problematic soil is done; replacement is done by a better quality material, or the soil is treated with an additive. In the present study, using fly ash obtained from Sesa Sterlite, Jharsuguda, Odisha, stabilization of black cotton soil obtained from Nagpur is attempted. With various proportions of this additive i.e. 10%, 20%, 30%, 40% & 50%, expansive soils is stabilized. Owing to the fact that fly ash possess no plastic property, plasticity index (P.I.) of clay-fly ash mixes show a decrease in value with increasing fly ash content. In conclusion, addition of fly ash results in decrease in plasticity of the expansive soil, and increase in workability by changing its grain size and colloidal reaction. Tested under both soaked and un-soaked conditions, the CBR values of clay with fly ash mixes were observed. Analysis of the formerly found result exposes the potential of fly ash as an additive that could be used for improving the engineering properties of expansive soils.

Some studies on the effect of fly ash and lime on physical and mechanical properties of expansive clay

Abstract: Fly ash is one of the most plentiful and versatile of the industrial by-products. At present, nearly 150 million tonnes of fly ash is being generated annually in India posing dual problem of environmental pollution and difficulty in disposal. This calls for establishing strategies to use the same effectively and efficiently. However, it is only in geotechnical engineering applications such as the construction of embankments/dykes, as back fill material, as a sub-base material etc., its large-scale utilization is possible either alone or with soil. Soil stabilization can be achieved by various means such as compaction, soil replacement, chemical improvement, earth reinforcement etc. Usually, in the case of clay soils, chemical improvement is commonly most effective since it can strengthen the soil, to remove its sensitivity both to water and its subsequent stress history. Among chemical means or additives, fly ash/lime provides an economic and powerful means of improvement, as demonstrated by the significant transformation that is evident on mixing with heavy clay. In the present investigation, different percent fly ashes (10%, 20%, 40%, 60% & 80%) were added to a highly expansive soil from India by dry weight of the natural soil, and subjected to various tests. The important properties that are necessary for using fly ash in many geotechnical applications are index properties, compaction characteristics, compressibility characteristics, permeability and strength. Based on test results, it has been found that using fly ash for improvement of soils has a two-fold advantage. First, to avoid the tremendous environmental problems caused by large scale dumping of fly ash and second, to reduce the cost of stabilization of problematic/marginal soils and improving their engineering properties for safe construction of Engineering Structures.

The Study of Mixture Design for Foam Bitumen and the Polymeric and Oil Materials Function in Loose Soils Consolidation

Abstract: Due to the enormous growth of new chemicals, especially polymer materials in construction projects, and the importance and effectiveness of these new materials in poor soil stabilization, recently has closed chemistry and polymer sciences to civil science. The use of materials such as bitumen in stabilization of flowing and loose soil and using of polymer resins reflects the effect of these substances is very high on construction projects. Considering the importance of oil and polymer materials in soil stabilization, in this study performance of polymer materials and their comparison have been investigated. Oil materials such as bitumen can be used to stabilize the soil, and polymer resins such as polyvinyl alcohol and polyvinyl acetate, and also pointed polypropylene synthetic fiber can be considered as polymer materials. Bitumen foam is one of the fixative materials that obtain by adding water to hot bitumen, and is applicable to a wide range of stone materials. In addition to, polymer resins increase the burden go loose soils. Polymer fibers due to high durability and easy application and no problem at saturation conditions are highly regarded by civil engineers.

Centrifuge Modeling of Rocking Foundations on Improved Soil

Abstract: The nonlinear response of shallow foundations when subjected to combined loading has attracted the attention of the research engineering community over the last few decades, providing promising evidence for incorporation of such response in design provisions. Failure in the form of soil yielding or foundation uplifting may accommodate high ductility demand and increase the safety margins of the whole structure. However, increased permanent displacement and rotation may occur. This paper explores the concept of shallow soil improvement as a means to locally increase soil strength and thus limit rocking-induced settlement. Bearing in mind that the rocking mechanism is relatively shallow, failure may be contained in a soil layer of known properties that extends to a shallow depth beneath the foundation. The performance of a system in poor soil conditions, on an ideal soil profile, and on improved soil profiles was explored through a series of centrifuge tests at the Center for Earthquake Engineering ...

Soil Stabilization as an Avenue for Reuse of Solid Wastes: A Review

Abstract: Industrialization has resulted in rapid improvement in the standards of living; however, it has also resulted in pollution and generation of solid wastes that have recently reached epic proportions. An effective waste management alternative is the need of the hour. Reuse of waste materials have been advocated for quite a while now and the utilization of industrial wastes in improving the properties of poor soils open up a new avenue for solid waste management. Expansive soils have been one of the most problematic soils encountered by a Civil Engineer. A lot of techniques are available for stabilization of such poor soils including lime and cement stabilization. However, the utilization of solid wastes in soil stabilization is an area of potential and promise. And it also provides the double advantage of waste management along with soil improvement. With this as base, this paper attempts to review the various industrial wastes that have been adopted in soil stabilization as a standalone stabilizer without lime or cement, in order to shed light into the prospects of increased utilization of solid wastes in soil stabilization.

Experimental insights of using waste marble fines to modify the geotechnical properties of a lateritic soil

Abstract: Marble spoil waste is an environmental nuisance. The effects of adding waste marble fines (WMF) on the plasticity, strength and permeability of a lateritic clay have been investigated for its potential use as a soil modifier or stabilizer of road pavement layer materials or earth-building materials. The chemical compositions of the WMF and soil were determined using X-ray fluorescence and atomic absorption spectrometry, respectively. The specific gravity, Atterberg limits, compaction, strength and permeability characteristics of the soil were determined for varying proportions of the soil-WMF blends. The properties of the natural soil–classified as clay of low plasticity (CL) and A-7-6(7), according to unified soil classification and AASHTO classification systems, respectively–were improved after the addition of 10% WMF such that it behaves like a silt of low plasticity. Therefore, WMF is recommended as a low-cost soil modifier or stabilizer for lateritic soil and well-suited for road construction applications

Effect of Electrolyte Lignin and Fly Ash in Stabilizing Black Cotton Soil

Abstract: Subgrade is one of the important layers of any pavement. It must be able to support loads transmitted from pavement structure without excessive deformation under adverse climatic and traffic conditions. In this investigation, laboratory studies were carried out to evaluate the influence of a commercial electrolyte lignin stabilizer (ELS), fly ash (FA) and a combination of both, on black cotton (BC) soil procured from North Karnataka region in India. Basic geotechnical and engineering properties like unconfined compressive strength (UCS), California bearing ratio (CBR), etc. were determined for both untreated and treated soil. Dynamic repeated load test was conducted to examine the fatigue behaviour of the soil. Durability of the soil was checked by wet-dry (WD) and freeze-thaw (FT) cycle tests, and swelling properties by free swell index test. From the studies, it was observed that consistency limits, dry density, UCS and CBR values were improved for treated soil, with curing periods of 1, 7 and 28 days. Weight loss in FT test was less than 14 % for 12 cycles, which ensures that the stabilized soil has become durable. But none of the samples were observed to be withstanding above five cycles in wet-dry test. Soil stabilized with ELS and FA showed better results compared to soil with only ELS. Swelling was reduced to a great extent with 28 days curing period for the former one. From the experimental results, it can be concluded that this chemical can be used as a stabilizer for existing BC soil in site to enhance its subgrade strength.

Assessing geo-mechanical and micro-structural performance of modified expansive clayey soil by silica fume as industrial waste

Abstract: Expansive soils may cause disaster if not adequately taken care of. Lime continues to be commonly used for modification of these types of soils although it may have limited success in some applications. Thus, the present study was performed to address the viability of using silica fume (SF) as industrial waste to modify the behavior of expansive soils. This achieves the double objectives of overcoming the restrictions associated with lime treatment, and also of providing reliable data for using SF in the field of geotechnics to reduce its environmental cost. The additives including lime, SF, and lime-silica fume (LSF) mixture were separately added to the expandable smectite clay at wide ranges from 2% to 30% by mass, respectively. A set of laboratory tests including Atterberg limits, swelling, unconfined compression strength, permeability, electrical conductivity, and pH measurement were carried out at various curing periods to evaluate different influences of the additive types on the soil performance. The SSA and sedimentation analyses were conducted to assess the soil microstructure changes. The micro level structures of natural and modified clayey soil samples and their chemical composition were also studied using scanning electron microscope (SEM) equipped with Energy Dispersive X-ray (EDX) microanalysis. The results show that the geo-mechanical properties of highly expansive soil can be modified by the large content of lime. Besides, with the addition of lime and inadequate curing, where mainly flocculation occurs, the permeability of soil is negatively affected and slight increase in strength is observed. On the other hand, the addition of SF alone, even up to 30%, has less effect on the swelling power and produces a negligible change in the soil strength, regardless of the curing periods. It is found that the defects arising from the lime treatment can be greatly enhanced by the use of lime-silica fume mixture. Based on the results of macro and microstructure tests, the LSF blend improves the engineering parameters of smectite with a lower amount of lime and shorter curing time as compared with lime treated samples. This can occur due to extending the synthesis of the new pozzolanic compounds. It also significantly decreases the soil permeability through physicochemical interactions and induces a sharper decline in free lime, which results in the decrease of post instability problems in chemically modified soil. The study concludes that the combination of silica fume and lime can be successfully utilized as an additive to increase the efficiency of soil stabilization from economic, technical and environmental point of views.

The efficacy of lignosulfonate in controlling the swell potential of expansive soil and its stabilization mechanisms

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Effect of Anisotropy of Fibers on the Stress-Strain Response of Fiber-Reinforced Soil

Abstract: Reinforcing soil with fibers is a useful method for improving the strength and settlement response of soil. The soil and fiber characteristics and their interaction are some of the major factors affecting the strength of reinforced soil. The fibers are usually randomly distributed in the soil, and their orientation has a significant effect on the behavior of the reinforced soil. In the paper, a study of the effect of anisotropic distribution of fibers on the stress-strain response is presented. Based on the concept of the modified Cam clay model, an analytical model was formulated for the fiber-reinforced soil, and the effect of fiber orientation on the stress-strain behavior of soil was studied in detail. The results show that, as the inclination of fibers with the horizontal plane increased, the contribution of fibers in improving the strength of fiber-reinforced soil decreased. The effect of fibers is maximum when they are in the direction of extension, and vice versa. (C) 2014 American Society of Civil Engineers.

Review on Stabilization of Soil Using Coir Fiber

Abstract: Soil stabilization has become a major issue in construction engineering and the researches regarding the effectiveness of using natural wastes are rapidly increasing. The use of natural fibers to reinforce soil is an old and ancient idea. Consequently, randomly distributed fiber reinforced soils have recently attracted increasing attention in geotechnical engineering. The main aim of this paper, therefore, is to review

Soil Stabilization with Using Waste Materials against Freezing Thawing Effect

Abstract: Freezing–thawing processes hapenning in seasonally cold climate cause deformation of soil in time of freezing and strength loss while thawing. Problems of ground frost heave and soil softening belong to the important factors, that could cause serious damage and financial loss. Bayburt tuff and tuffites known as Bayburt Stone mines, located around Bayburt, play important role on economy of the Bayburt city. As a result of researches in 2005 total of 2 535 700 tons proved reserve were determined several places in Bayburt. The goal of this study is proving, that deposits of Green Bayburt Stone wastes, created in the stone quarries during the stone processing, can be used as a stabilizing material. By recycling the waste material rejected stone was mixed with lime and used as a soil stabilizator against freezing–thawing effect. Prepared natural and stabilized soil samples were subjected to freezing–thawing cycles after curing for 28 days. After the freezing–thawing cycles, compressive strength of the samples was measured to investigate the influence of the additives on the freezing–thawing properties of soil samples. As a result of this study, it was determined that samples stabilized with Green Bayburt Stone mixtures have high freezing–thawing durability as compared to unstabilized samples. As a consequence, it was seen that those mixtures can be successfully used as an additive material to enhance the freezing–thawing effects of cohessive soils.

Soil modification by addition of cactus mucilage

Abstract: This research provides insight on the laboratory investigation of the engineering properties of a lateritic soil modified with the mucilage of Opuntia ficus-indica cladodes (MOFIC), which has a history of being used as an earthen plaster. The soil is classified, according to AASHTO classification system, as A-2-6(1). The Atterberg limits, compaction, permeability, California bearing ratio (CBR) and unconfined compressive strength of the soil were determined for each of 0, 4, 8 and 12% addition of the MOFIC, by dry weight of the soil. The plasticity index, optimum moisture content, swell potential, unconfined compressive strength and permeability decreased while the soaked and unsoaked CBR increased, with increasing MOFIC contents. The engineering properties of the natural soil, which only satisfies standard requirements for use as subgrade material, became improved by the application of MOFIC such that it meets the standard requirements for use as sub-base material for road construction. The effects of MOFIC on the engineering properties of the soil resulted from bioclogging and biocementation processes. MOFIC is recommended for use as a modifier of the engineering properties of soils, especially those with similar characteristics to that of the soil used in this study, to be used as a pavement layer material. It is more economical and environment-friendly than conventional soil stabilizers or modifiers.

Assessing Failure Envelopes of Soil–Fly Ash–Lime Blends

Abstract: This study aims to establish the influence of curing time and the amount of lime and porosity in the assessment of the Mohr-Coulomb failure envelope of fly ash–lime-treated soils based on unconfined compressive strength (σc) and splitting tensile strength (σt) of such materials. Founded on the concept that the σt/σc relationship is unique for each specific fine-grained soil, fly ash, and lime blends, it is shown that the angle of shearing resistance of a given lime-treated soil is independent of the porosity and the amount of lime of the specimen and that cohesion intercept is a direct function of σc (or σt) of the improved soil, which depends of the porosity and volumetric amount of lime of the soil–fly ash–lime blends. Finally, the concepts are tested with success for a sandy soil treated with fly ash and lime at distinct curing time periods, considering moderate to strong cementation levels.

Laboratory Investigations of In Situ Stabilization of an Expansive Soil by Lime Precipitation Technique

Abstract: The present investigation examines the efficiency of an in situ lime precipitation technique in stabilizing expansive soil through laboratory-scale model tests. Expansive soil was compacted in a cylindrical mold and sequentially permeated with CaCl2 and NaOH solutions into the expansive soil through a central hole filled with coarse sand. Successive permeation of CaCl2 and NaOH solutions into the compacted expansive soil resulted in precipitation of lime in the expansive soil mass. The precipitated lime reduced the plasticity index, controlled the swell–shrink potentials, and increased the unconfined compressive strength of the expansive soil by both strong lime modification reactions and soil–lime pozzolanic reactions. The results are corroborated with microfabric studies on lime precipitation treated specimens, which showed the formation of cementation bonds.