Swelling Of Expansive Soil Research Articles

Effects of Potassium Solutions on Swell Potential of Mae Moh Expansive Soil

This paper presents a field experiment of using potassium solutions to reduce swelling of expansive soil in the area of Mae Moh District, Lampang Province, Thailand. Based on the fact that the difference between montmorillonite in expansive soil and illite in non-expansive soil is the silica-gibbcite structure of the former was bonded by water molecules but those structures of illite was bonded by potassium ions. Therefore, an assumption of this research was if the expansive soil were soaked in potassium solution, monmorillonite may change to illite, and the soil should no longer swell. The field experiment was conducted by drilling holes of approximately 2 meters depth. Then, released potassium hydroxide in the forms of solution and flakes as well as potassium chloride solution and potassium nitrate solution into the holes. Kept the holes fill with the solutions at all time. After 30 days and 90 days, drilled other holes nearby the solution-fill holes to collect soil samples for laboratory tests. The investigation revealed that only the 20% potassium hydroxide can reduce the swelling of Mae Moh expansive soil. The X-ray diffraction test discovered that after 30 days of applying KOH solution to the expansive soil stratum, only illite and muscovite but montmorillonite was found, then after 90 days only muscovite was found. Based on academic articles in chemistry and geology, the transformation of montmorillonite to illite, and transformation of illite to muscovite are possible. The study of using potassium hydroxide solution should be studied extensively because it will be useful for existing buildings.

Improvement of the Bearing Capacity and Swelling of Ciampel Expansive Soil using Waste Foundry Sand

Road construction on expansive soil often suffers damage because of large shrinkage properties due to changes in water content. This study aims to analyze the bearing capacity and swelling of expansive soils stabilized using WFS as an effort to find solutions for improving expansive soils by utilizing local materials based on industrial waste. In this study, the soil was mixed with waste foundry sand as an additive material with a concentration of 2.5%, 5%, 7.5%, and 10% of the soil dry weight. Tests carried out included Compaction, California Bearing Ratio, and Swelling Potential based on ASTM standards. The soil stabilized with 10% WFS showed a significant increase in CBR value with changes of 64.89% (unsoaked) and 438.69% (soaked) to the original soil CBR value. WFS 10% in the soil was able to suppress the expansion value of the expansive soil by 93.16% to the swelling value of the original soil. WFS content of 10% in the soil can be recommended as an expansive soil stabilization material because it can increase the bearing capacity of the soil and reduce the level of swelling of the soil.

Mechanisms Underlying the Overturning Failure of Terraced Field Side Walls Due to Expansive Soil Swelling During Layer‐By‐Layer Saturation

The stability of side walls in terraced fields constructed within expansive soil regions represents a critical challenge, often leading to structural failure due to the unique wetting–swelling behavior of the soil. This study employs a comprehensive approach, integrating analytical and numerical methods to elucidate the mechanism of overturning failure attributed to the swelling effect of expansive soil under conditions of layer‐by‐layer saturation. Initially, the earth pressure acting on side walls, constructed from fiber ecological bags, is assessed in their natural, unsaturated state using Bishop’s formula for unsaturated shear strength. The study further explores the failure mode through one‐dimensional analytical analysis, focusing on the horizontal and unrestrained expansion of expansive soil during progressive saturation. Subsequently, the deformation of the side wall and the swelling effect of the soil are numerically evaluated. This is achieved by analogizing the wetting–swelling deformation field in expansive soil to an equivalent temperature field, thereby facilitating the use of finite element numerical simulation to investigate the overturning failure mechanism. Findings indicate that in the natural unsaturated state, the side walls remain stable under no earth pressure. However, as saturation depth attains a critical depth of 1.4 m during layer‐by‐layer saturation, the upper wall rotates outward in the form of local overturning failure, and the corresponding infiltration saturation depth is the critical depth for the local instability of the side wall. The investigation identifies the wetting–swelling effect as the predominant factor leading to the structural failure of side walls in terraced fields situated in expansive soil areas. Moreover, a critical infiltration saturation depth of 2.6 m is determined, beyond which the stability of the side walls is compromised. This research contributes significantly to the understanding of the failure mechanisms affecting terraced agricultural infrastructures in expansive soil regions, offering a theoretical foundation for the development of more resilient construction strategies.

Effects of wetting and drying cycles on the swelling pressure and free swelling of expansive soil

The aim of the current study is to investigate the influence of consecutive wetting and drying cycles on the free swelling and swelling pressure properties of a potentially expansive soil. The investigated sample consisting of high-plasticity inorganic clay with high consistencylimit values and extremely high swelling potential. The adopted methodology comprised free swelling and swelling pressure tests – based on the post-swelling loading method, under 0.5 kPa overload. Both tests were conducted in a cyclic manner by implementing eight wetting and drying cycles. Results have shown that the wetting and drying cycles acted as agents influencing the swelling pressure and free swelling properties of the expansive soil. It was found that the expansive soil sample, when moistened and then dried to its initial moisture content, time and again, showed higher values of swelling pressure and free swelling at the first moistening cycle. It was also observed that the expansive soil sample decreases its expansive behavior as the number of wetting and drying cycles increases.

An Experimental Investigation on Shear Strength Behaviour of Unsaturated Clays on Effect of Spent Bleaching Earth and Misspend Cement

Abstract: In any kind of structure, expansive clay is a major cause of undulations. Numerous structures suffer damage and serious problems as a result of expansive soil swelling. The viability and environmental suitability of waste materials are the subject of extensive research by numerous research organizations. Waste products from the cement warehouse and oil industry include wasted bleaching earth and misspend cement. It is the best method to use in expansive soils to avoid issues with dumping and storage. Unconfined compressive strength and tri-axial compressive strength were used to identify a stabilization process. Any structure's stability depends on the strength of the underground soil on which it is built. All of a structure's loads are basically transferred to the ground directly. There are a variety of failures that can occur if the underlying soil is not stable enough to support transferred loads, including structure settlement, cracks, and so on. Soil improvement is necessary to solve this problem because it reduces the risk of structural damage in the future and reduces construction costs. To make ordinary soil stable enough to support the structural loads, a variety of improvements can be made. In this study, both regular and stabilized soil can be used in a number of tests. This paper explains the strength behavior of SBE treated black cotton soil reinforced with MC. The various percentage of SBE as 5%, 10%, 15%, 20% and 25% was used to find out the optimum value of RBI Grade. MC has been randomly included into the SBE treated soil at four different percentages of MC content, i.e. 2%, 4%, 6%, 8% and 10%.

Critical stress evaluation of rigid pavement due to the presence of water in expansive soil subgrade

The use of various types of rigid pavement is widespread because of its superiority in resisting heavy load vehicles. However, traffic loading complexity and subgrade response cause uncertainty during the design process. The presence of water in expansive soil issue swelling affected the flexural behavior of a rigid pavement slab. Rigid pavement relies heavily on the support and stability of the subgrade. Plain concrete is very weak in resisting tensile stresses so that the failure of rigid pavement slab structures often occurs in the expansive subgrade zone. Therefore, this study aims to numerically analyze the relationship between variations in the thickness of rigid pavement slabs on the flexural behavior parameters, such as critical and tensile stresses that affected water in expansive soil. The concrete’s performance limit was determined, using its material’s constitutive equation curve, and the data were analyzed using the finite element method. The results showed that the presence of water in expansive soil caused a change in soil volume (swelling), a reduction in soil bearing capacity (shrinking), and consequently, a rigid pavement cracked due to water variations in the subgrade. Generally, increasing the thickness of rigid pavement is a common method for mitigating the detrimental effects of expansive soil swelling. It is possible to provide reinforcement in other forms, which provide an opportunity to improve the performance of the concrete slab as a rigid pavement. For example, stabilization of expansive soil with materials capable of reducing its expansive power can be done but it requires large resources to realize it. Another method is to provide reinforcement to the rigid pavement slab structure, so that the rigid pavement slab is able to withstand traffic loads and also the expansion and shrinkage behavior of the expansive soil

Comparison of Costus dewevrei De Wild. and T. Durand Admixture with Lime and Cement in Soil Stabilization

The study investigated the use of cement and lime as composite mixture with Costus dewevrei De Wild. & T. Durand as for soil stabilization aimed at improving the properties of expansive soils used for road pavement. The maximum dry density (MDD), optimum moisture content (OMC), consistency limits, California bearing ratio (CBR) and unconfined compressive strength (UCS) of the soil were subjected test to ascertain the performances of the cement and lime with bagasse composite. The results showed that the composite materials improved the soil properties, but the maximum dry density (MDD), optimum moisture content (OMC), liquid limit (LL), plasticity index (PI), California bearing ratio (CBR) and unconfined compressive strength (UCS) of the expansive soil stabilized with cement and bagasse ash composite were greater than the soil samples stabilized with lime and bagasse ash composite. Meanwhile, the value of plastic limit (PL) obtained from the soil sample stabilized with lime and bagasse ash was higher than the value recorded in the soil sample stabilized with cement and bagasse ash. The optimum values UCS and CBR were recorded at 8% combined proportion of bagasse ash with cement and lime. Therefore, the improvement recorded in the soil properties proved that the combined effect of bagasse ash obtained from Costus dewevrei De Wild. & T. Durand and cement or lime, is effective and can be applied as stabilization material to reduce shrinkage and swelling of expansive soil that often lead to road pavement failure.

Determination of Diameter of Belled Shafts with respect to Uplift Forces Resulted From Expansive Soil Layer in Active Zone

Expansive soils are found in many parts of the world that are especially arid and semi-arid regions. They have caused several damages of lightweight structures for decades. For this reason, a more suitable foundation type should be selected and designed for the lightweight structures built on these soils. For example, the application of belled shaft foundation at expansive soil layer is preferable method in practice. However, one of the worst cases at the design of this foundation is accepted that the swelling of expansive soil placed in active zone. Therefore, this condition should be taken into account at the design process of this foundation. In this study, the diameter of belled shaft was separately determined with respect to some factors such as the diameter of shaft, the depth of active zone, the friction angle between shaft and soil, and the ratio between the undrained cohesion of soil at stable zone and the swelling pressure of expansive soil placed in active zone. In the calculation process, four different shaft diameters that are 0.3 m, 0. 45 m, 0.60 m, and 0.75 m were utilized. Also the depth of active zone that started from 1.5 m to 15 m was specified. To sum up, the optimum shaft diameter was found as 0.45 m.

Numerical Analysis of Piled-Raft Foundations on Multi-Layer Soil Considering Settlement and Swelling

Numerical modelling can simulate the interaction between structural elements and the soil continuum in a piled-raft foundation. The present work utilized a two-dimensional finite element Plaxis 2D software to investigate the settlement, swelling, and structural behavior of foundations during the settlement and swelling of soil on various soil profiles under various load combinations and geometry conditions. The field and laboratory testing have been performed to determine the behavior soil parameters necessary for numerical modelling. The Mohr–Coulomb model is utilized to simulate the behavior of soil, as this model requires very few input parameters, which is important for the practical geotechnical behavior of soil. From this study, it was observed that, as soil is soft and has less stiffness, the un-piled raft was not sufficient to resists and higher loads and exceeds the limits of settlement. Piled raft increases the load carrying capacity of soil, and the lower soil layer has a higher stiffness where the pile rests, decreasing the significant settlement. Further, the effects of (L/d) and (s/d) of the pile and Krs on the settlement are also discussed, detailed numerically under different scenarios. The swelling of expansive soil was also simulated in Plaxis 2D with an application of positive volumetric strain. The above-mentioned parametric study was similarly implemented for the heaving of foundation on expansive soil.

Numerical Modelling of Shallow Foundations on Expansive Shale: A Case Study of Jamshoro, Pakistan

This study analyzes expansive soil swelling under the shallow foundation using the Plaxis 2D FEM software. Under the impact of changing water conditions, expansive soil undergoes obvious volumetric changes, which often cause differential movements of the shallow foundations resting on it, which may lead to structural damage if no special precautions had been taken during the design process. In previous studies, the swelling of soil was simulated in Plaxis by applying the swelling potential with a positive volumetric strain, without considering water level changes, which proved to be not practical. This study demonstrates the time-dependent deformation (swelling) in expansive soil using the Plaxis 2D user-defined Swelling Rock Model in different soil and parametric conditions. The geotechnical properties of expansive shale were determined in the laboratory and by field testing, using parameters of the collected soil as input for the numerical model. Swelling of soil increased due to the increase of water level and decreased with the load. The heave was minimum in the center of the foundation (20 mm), attaining the maximum value at the corner (16 cm). The increase in the modulus of elasticity does not have much effect on soil swelling compared to soil settlement. The effect of matric suction-related changes on the swelling of soil due to the rise of the water table is not significant compared to the inherent soil swelling behaviour.

Analysis of shear strength of the expansive soil stabilized with kaolin at various soaking times

Expansive clay soils are high shrinkage soils that have low bearing capacity. So an effort is needed to reduce the nature of its swelling. One effort that can be done is the method of soil stabilization, where the soil is mixed with materials that can reduce soil swelling and increase the shear strength of the soil. One of the materials that can be used is kaolin powder. Kaolin is a stabilizing agent found in nature so it is easy to obtain. The purpose of this research is to analyse the decrease of expansive soil swelling and the value of its unconfined compression strength at various soaking times. The test was carried out by mixing 9% kaolin powder against dry soil weight. The stabilized soils were then compacted as samples to be soaked with time variations of 0 days, 3 days, 7 days, 10 days, and 14 days. The results of the test after soaking 14 days is a decrease of the stabilized soil swelling value up to 67.78%. The unconfined compression strength is increase up to 77.28% compared to its natural condition.

Prediction of swelling pressure of expansive soil using an improved molecular dynamics approach combining diffuse double layer theory

Swelling pressure of expansive soil is a fundamental parameter in the prediction of expansive soil behavior and also an essential quality indicator for geotechnical structure design. In this paper, we proposed a novel method by combining the diffuse double layer theory and molecular dynamics approach to predicting swelling pressure of expansive soil. The molecular structure was constructed based on the Na (Ca)-montmorillonite clay, which is the main mineral composition related to the swelling of expansive soil. The effects of electrical potential energy and van der Waals' energy were considered in this model. The proposed model was validated by comparing the predicted swelling pressure with the experiment results under different cation exchange capacities and dry density conditions. The capability of the model was discussed for different montmorillonite contents and interlayer cations. Two swelling pressure versus dry density graphs for montmorillonite with monovalent and divalent interlayer cations were developed for engineering application. The model calculated swelling pressures agreed well with the experimental results. This model provides a solid but cost-effective way to predict swelling pressure.

Effect of natural fiber reinforcement on strength response of alkali activated binder treated expansive soil: Experimental investigation and reliability analysis

Expansive soil possesses high swelling-shrinkage potential owing to moisture instability, resulting in loss of geomechanical strength. In this study, an effort is made to improve the shear strength properties of expansive soil by combined effects of alkali activated binder (AAB) with chemically treated hemp (THF) and coir fiber (TCF). AAB is produced by the reaction between alkaline binder of sodium silicate and sodium hydroxide in aluminosilicate precursors of Class-F fly ash and slag at various proportions. The effect of varying dosages of THF, TCF, and slag/fly ash ratio in the AAB soil mixture on compressive shear, tensile, and flexural strength is evaluated through a series of geotechnical characterization tests. It is observed that THF-AAB-soil shows higher interfacial bonding with strong interlocking density and tensile cracking resistance compared to TCF. Furthermore, in order to effectively consider the uncertainties associated with the design of subgrade for foundations, reliability indices against unconfined compressive strength and split tensile strength are predicted using Monte Carlo simulation through a non-linear regression model developed from experimental results. The study shows that the optimum dosages of fly ash-slag and fiber reinforcement are essential factors for controlling the swelling of expansive soil as well as improving its tensile strength.

WITHDRAWN: Effect of polypropylene fibre on swelling behaviour of black cotton soil

Abstract This paper discusses the laboratory study of performance on expansive soil reinforced with polypropylene fiber and demonstrates that discrete and randomly distributed polypropylene fiber is useful in restraining the swelling tendency of expansive soils. Swelling characteristics of remoulded expansive soil specimens reinforced with varying fiber content (f = 0.2%, 0.3%, 0.4% and 0.5%) and aspect ratio (l/b = 15, 30 and 45) were studied. One dimensional swell-consolidation tests were conducted on consolidometer specimens. Reduction in heave and swelling pressure was the maximum at low aspect ratios at both the fibers contents of 0.2%, 0.3%, 0.4%, and 0.5%. Finally, the mechanism by which discrete and randomly distributed polypropylene fiber restrain swelling of expansive soil is explained with the help of soil-fiber interaction.

Increasing density and cement content in stabilization of expansive soils: Conflicting or complementary procedures for reducing swelling?

The present study makes three contributions to the literature of expansive soils: (i) it proposes equations to predict soil swelling based on dry density and cement content, (ii) it checks the developed general equation by predicting the swelling of different expansive soils from the literature, and (iii) it designs experiments that investigate factors that have a significant influence on swelling. An experimental programme was carried out to analyse the expansion of bentonite–kaolin–cement blends. Different proportions of bentonite–kaolin, cement content, dry density, and moisture content were evaluated. A unique relation of the cement/porosity index was obtained for cement-stabilized expansive soils’ swelling; this index has been used before to portray strength, stiffness, and loss of mass of stabilized soils and is now shown to be applicable to describe swelling of expansive soils treated with Portland cement. In the present research, cement content and dry density are seen as conflicting parameters regarding the swelling of expansive soils, because increasing the amount of Portland cement reduces swelling and increasing the density (through compaction) causes higher expansion. A general swelling model is proposed and successfully checked with data from the literature; it is able to predict the swelling of expansive soils with different densities, expansive mineral, moisture content, and cement content.

Influence of Spent Bleaching Earth and Misspend Cement on Shear Strength Behaviour of Unsaturated Clays

Expansive clay is a major source of undulations induced in any type of structures. Swelling of expansive soils causes serious problems and produces harm to many structures. Many research organizations are doing extensive work on waste materials concerning the viability and environmental suitability. Spent bleaching earth and misspend cement are waste derivatives from oil industry and cement warehouse. To avoid dumping problem and storage problems, it is the best method technique applied in expansive soils. Attempts are made to investigate the stabilization process identified in unconfined compressive strength and tri-axial compressive strength.Stability of any structure depends on strength properties of underground soil on which it is constructed. Structures basically transfer all the loads come on itself directly to the ground. If the underlying soil is not stable enough to support transferred loads then various types of failure occur such as settlement of the structure, cracks and so on. To solve this issue, soil improvement is necessary because it not only lowers the construction cost but also cuts the risk of any damage of structure later on. Numerous improvement methods can be adopted to make ordinary soil stable enough to support the structural loads. In this research work a number of tests may conduct using both ordinary soil and stabilised soil. This thesis explains the strength behavior of SBE treated black cotton soil reinforced with MC. The various percentage of SBE as 5%, 10%, 15%, 20% and 25% was used to find out the optimum value of RBI Grade. MC has been randomly included into the SBE treated soil at four different percentages of MC content, i.e. 2%, 4%, 6%, 8% and 10%.

Swelling Suppression Mechanism of Compacted Expansive Soil Amended with Animal and Plant Based Biochar

Biochar has been recently explored in regulating swelling of expansive soil. However, those studies were conducted mainly on loose soil (from agricultural perspective), that have much lower density as compared to that in engineered landfill cover/slope cover. Further, the mechanism of swelling suppression in biochars, of different origin (i.e., plant and animal based) is rarely explored. The study aims to investigate swelling suppression mechanism of a compacted expansive soil under influence of plant and animal based biochars. Atterberg limits, free swelling rate as well as one dimensional swell tests on expansive soil were carried out at four different biochar contents (i.e., 0%, 5%, 10% and 15%) and two biochar types (woodchip and pig manure). The results show that: (1) When the biochar type is kept the same, the swelling characteristics of the modified samples decrease significantly with an increase in biochar content. Based on XRD tests, water sensitivity of the expansive soil after modification is obviously reduced due to the contraction of the hydrophilic mineral lattice. However, beyond biochar content of 10%, the effect on swelling characteristics of expansive soil is minimal; (2) Woodchip biochar has a better suppression capacity than pig manure biochar at higher biochar contents (> 5%). SEM tests observed through comparison that the pore development of woodchip biochar greatly outperforms that of pig manure biochar. Hydrophilic minerals of the expansive soil with 10% woodchip biochar had the smallest crystal spacing and the smallest peak area. Adsorption, flocculation and cation exchange between biochar and clay particles limited the water entering the soil and reduced the thickness of the diffused double layer. Hence, it reduced swelling ability of expansive soil.

Constitutive model describing the hydro-mechanical behaviors of compacted bentonite clay based on the crystal surface phenomena

A constitutive model for unsaturated expansive soil based on the crystal surface phenomena is proposed. The behavior of the proposed model is described as a double structure, with the soil skeleton and the interlaminar behaviors. The soil skeleton behavior is modeled by the Cam clay type model based on the Bishop’s effective stress, which can consider the degree of saturation-induced hardening and inelastic behavior in the over-consolidated region and is capable of describing hydraulic collapse. On the other hand, the interlaminar behavior is give as a result of the interlaminar equilibrium of clay minerals. The diffusion double layer repulsive force in the interlaminar equilibrium varies with the degree of saturation, and it mainly causes the hydraulic swelling of expansive soil. The performance of the model is validated through the simulations of the suction-controlled oedometer tests on the heavily compacted bentonite.

COUPLED AND UNCOUPLED APPROACHES FOR THE ESTIMATION OF 1-D HEAVE IN EXPANSIVE SOILS DUE TO TRANSIENT RAINFALL INFILTRATION: A CASE STUDY IN CENTRAL VIETNAM

In this study, we utilized the coupled and uncoupled approaches in Geostudio commercial program to simulate the swelling of expansive soil caused by rainfall infiltration. For the coupled analysis in general, the infiltration of rainfall and subsequent heave are modeled using fully coupled formulation in SIGMA/W; specifically, the displacements and pore-water pressure changes are computed simultaneously. In the uncoupled analysis, rainfall-induced pore-water pressure change was simulated using SEEP/W alone and the resulting pore-water pressure change was employed in SIGMA/W for the volume change analysis. In other words, to analyze the problem in an uncoupled manner, the pore-water pressure changes and volume changes are computed separately. For the above purpose, the residual soil in Bac Ai district, Ninh Thuan province, South Central Vietnam, a well-known place with expansive soil problems was considered. The result shows that both proposed methods are promising tools and can be used in engineering practice for the estimation of the 1-D heave due to rainfall infiltration with respect to time.

Behavior of Swelling Soil Treated by Grid Geocell Columns under a Tank Footing

Fuel tanks usually induce large settlements due to heavy loading which requires treatment for the underlying soils. In this paper, a method of treating the swelling of expansive soil is presented. The method is simply based on the embedment of a geogrid (or a geomesh) in the soil. The geogrid is extended continuously inside the volume of soil where the swell is required to be controlled and orientated in the direction of swell. Soils with different swelling potentials were employed; bentonite-based Na and kaolinite mixed with bentonite. To investigate the swell, swell- partial shrinkage and other phenomena for untreated soils in comparison with their counterparts of treated soils, laboratory model tests were carried out in 800 × 200 mm box container and 600 mm in height. Swelling and cyclic wetting along with drying tests were carried out on each sample with pore water pressure measurement. Swelling test in the model reveals promising results of the proposed treatment technique. The improvement factors, range between 30% to 60 % depending on the geogrid stiffness, soil plasticity, fill martial (sand or clay) and dry density of sand fill. The geocell has a significant effect on the experimental results. The reduction in swell increases with increasing the geogrid stiffness and when using sand as a fill material, the reduction is apparently due to a strong interference bond which restricts the relative movement between the clay and the grid. The use of geocell filled with the same expansive soil causes a decrease by about 19% and 42 % in the final swelling of soils, whereas filling the cell with sand causes about 35 % and 64 % reduction for the soils, respectively. The treatment method shows the activity of geocell fill material in reducing the matric suction (pore water pressure). When sand is used, a new channel is created for the dissipation of pore water pressure.