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In-situ stabilization of an expansive soil in desiccated state
Abstract
This paper examines the efficiency of in-situ stabilization of expansive soil by lime slurry technique in desiccated state through laboratory and field experimental studies. The laboratory and field studies consists of permeating 34% hydrated lime slurry into the desiccated soil through vertical holes and measuring the physico-chemical, index and engineering properties before and after treatment at different radial distances. The distinct changes in the physico-chemical and index properties of the expansive soil indicate the occurrence of lime modification reactions and pozzolanic reactions on lime migration into the inter-connected shrinkage cracks. The lime slurry treatment increased the soil pH (≈ 12) to the levels that are conducive for the pozzolanic reactions to occur. The soil-lime reactions reduced the swelling potential and increased the unconfined compressive strength of lime slurry treated expansive soil. The test results encourage the application of lime slurry technique to expansive soil deposits during dry season upon development of shrinkage cracks.. J. Ross Publishing, Inc.
... They are vastly spread around the globe and are considered problematic for engineering projects, due to their swell-shrink behavior, posing severe threats to construction activities and human lives [2]. Due to continuous growth in urbanization and industrial developments, the availability of favorable soil conditions at construction sites has decreased; hence, in some instances, construction on the ES cannot be avoided [3]. Therefore, improving the geotechnical behavior of the ES has been a vital consideration for researchers throughout the construction record [4,5]. ...
... With the addition of WGP to the ES, the SP, and LL were reduced significantly, while the MDD increased. Abdul and Mahdi [20] used the WGP for the improvement of subgrade soils at different percentages (3,5,7, and 9 % by dry weight of the soil) finer than a 75-μm sieve. Results showed that with an increase in WGP content, the LL, PL, and PI decreased, whereas the UCS and direct shear strength increased. ...
... They are vastly spread around the globe and are considered problematic for engineering projects, due to their swell-shrink behavior, posing severe threats to construction activities and human lives [2]. Due to continuous growth in urbanization and industrial developments, the availability of favorable soil conditions at construction sites has decreased; hence, in some instances, construction on the ES cannot be avoided [3]. Therefore, improving the geotechnical behavior of the ES has been a vital consideration for researchers throughout the construction record [4,5]. ...
... With the addition of WGP to the ES, the SP, and LL were reduced significantly, while the MDD increased. Abdul and Mahdi [20] used the WGP for the improvement of subgrade soils at different percentages (3,5,7, and 9 % by dry weight of the soil) finer than a 75-μm sieve. Results showed that with an increase in WGP content, the LL, PL, and PI decreased, whereas the UCS and direct shear strength increased. ...
... In most situations, the desired soil required to use as a construction material is located far from the site projects and its transportation represents a great challenge. When a site investigation reveals the existence of unpreferable soils such as expansive soils with high-plasticity clay, it is essential to set a suitable scheme to enhance the soil engineering characteristics [1,2,3,4,5,6,7]. For example, Bentonite clay is a common expansive soil that undergoes high volume changes (eight times its original volume) when the moisture content increases which may cause structural damage lead to damage to the structural members like cracking in reinforced foundations and borders, curbs swelling and eventually produces deformation indoors and floors [8,9,10]. ...
Bentonite clay is the soil that undergoes high volume changes (swelling) when its moisture content increases. The soil swelling may cause structural damage leading to damage to structural members like cracking in reinforced foundations and borders, curbs swelling, and eventually produces deformation indoors and on floors. In this study, Bentonite clay with expansive characteristics was used and mixed with various amounts of Pulverized waste glass PWG (0%, 5%, 10%, and 15%). Two types of PWG were prepared: fine glass (passing sieve No. 200) and coarse glass (passing sieve No. 2 mm). Laboratory experiments were performed on Bentonite specimens blended with different amounts of PWG. The results showed that the addition of 15% by Bentonite weight of 2 mm of PWG reduces the Atterberg limits considerably. Moreover, a noticeable reduction was observed in the Bentonite samples' free swell and swelling pressure after being treated with different amounts of PWG. The observed advantages of adding the PWG to Bentonite clay soil by decreasing the volume changes and enhancing the overall properties of Bentonite clay reflect the suitability of using PGW as a good soil stabilizer. Besides reducing the impact of waste glass on the environment due to its non-biodegradable nature.
... In addition, in some project areas where the soil is the main construction material, and suitable soil material sources are not involved at the site and transportation of these require a considerable cost. The presence of high-plasticity soil in the project site is not suitable for the structures to be built on; therefore, stabilizing the soil is crucial [13][14][15][16][17][18][19]. ...
Soils are the most used construction materials in engineering projects, such as embankments, highways, and railways, in which huge amounts of soil are required. Unfortunately, sometimes, these soils are high expansive clay that makes problems to these projects, and at the same time, there are waste and by-product materials such as limestone powder that has not appropriately exploited in Iraq and causes environmental problems. This study aims to investigate the effect of limestone powder on the geotechnical properties such as unconfined compressive strength (UCS), compressibility indices, Atterberg limits, and swelling characteristics of high-plasticity clay (CH) in Erbil city in the Kurdistan Region of Iraq as this region is rich in limestone rocks. The high expansive clay was treated by different percentages (6%, 12%, 18%, 24%, 30%, and 36%) of limestone powder. The results indicated that the geotechnical properties could be improved by using limestone powder. Also, the optimum percentage of limestone powder that can be added to expansive soil is recommended.
... In some situation, construction on such type of soil cannot be avoided, and the sources of suitable materials may be not near to the site and transportation of them need significant effort. Therefore, the improvement of such type of soil is crucial [14][15][16]. This improvement includes increasing the strength and durability of expansive soils, as well as decreasing the consistency limits and the shrinking-swelling behavior [17][18][19][20]. ...
Expansive soils expand and lose their strength when wetted and shrink when dried, and this makes a considerable volume change. Construction on expansive soils has made problems around the world for different civil engineering projects such as highways, railways, embankments, and foundations. Therefore, the improvement of expansive soils is crucial, especially for road construction. The strength improvement of these types of soils can be gain by adding another material, and waste glass powder (WGP) was selected for this study. The WGP was crushed and mixed with the soil sample with various percentages: 2.5%, 5%, 10%, 15%, and 25% by the dry weight of the soil. Various laboratory tests were conducted for the treated and untreated expansive soil with the different percentages of the WGP, including Atterberg limits, compaction, free swelling, unconfined compressive strength (UCS), direct shear strength, and California bearing ratio (CBR) tests. According to the test results, adding WGP to the expansive soils has a significant impact on the consistency and shear strength of the soil sample. In addition, improving subgrade expansive soil with 15% of WGP decreases the thickness of the sub-base by about 63%. The optimum percentage of the WGP for enhancement this type of soil is around 15%.
... In some sites, the sources of earth materials are far away from the projects and transportation of these require considerable endeavour. Expansive soils such as high-plasticity clay (CH) are not suitable for this purpose and presence in some locations; therefore, their treatment is essential (Bhuvaneshwari, Robinson, and Gandhi 2010;Seco et al. 2011;Thyagaraj and Suresh 2012;Chowdhury 2013;Thyagaraj, Samuel, and Kumar 2016). In the Kurdistan Region of Iraq, there is no effective factory for recycling waste glasses. ...
Soil is a material most used in the field of civil engineering. High-plasticity clay (CH) in some parts of the Kurdistan Region of Iraq, as well as globally, causes noticeable damage to buildings and roads during seasonal changes. In some circumstances, construction on CH cannot be avoided; therefore, soil stabilization is crucial. In this study, waste glasses are collected then crushed and sieved via sieve number 200 (0.075 mm), and the glass powder is mixed with the expansive soil in different percentages: 6%, 12%, 18%, 27%, and 36% of the dry weight of soil. Atterberg limits, standard compaction, unconfined compressive strength, consolidation, and swelling tests are conducted for the soil samples with and without glass powder. According to the test results, the Atterberg limits, maximum dry density, optimum moisture content, unconfined compressive strength, consolidation, and swelling characteristics are improved by adding glass powder as a stabilizer.
... The growth of the ettringite in the voids resulted in the reduced shrinkage during drying of the stabilized soil. Figures 12a and c (Thyagaraj and Suresh 2012). SEM and EDAX analysis of 28 days cured lime-stabilized soil contaminated with sulphate solutions clearly show the rod like crystals and marked peaks corresponding to Ca, Al and S in Figures 11b, 12b and 12d. ...
Lime stabilization is an age-old technique for controlling the swell-shrink characteristics of the expansive soil. However, the presence of sulphate in the expansive soils renders the lime stabilization ineffective due to the formation of detrimental compounds – ettringite and thaumasite. The formation of these detrimental compounds can be counteracted by treatment with low-calcium or non-calcium based stabilizers. However, there is a possibility of sulphate contamination post lime stabilization through external sources. Therefore, the present study brings out the effect of short-term sulphate contamination on lime-stabilized expansive soil using sodium sulphate solution. To achieve this objective, the lime-stabilized expansive soil was cured for 1, 7 and 28 days, and subsequently mixed with sulphate solutions of 5000–20,000 ppm concentration and allowed to equilibrate for 1 day. The experimental results showed that the sulphate contamination had a significant effect on the soil structure, physico-chemical and index properties of lime-stabilized soil. The mechanism governing the deterioration of the stabilized soil depended on the curing period of lime-stabilized soil prior to contamination with sulphate. Short-term sulphate contamination of lime-stabilized soil cured for 1 and
7 days resulted in highly flocculated structure, whereas the lime-stabilized soil cured for 28 days resulted in the formation of ettringite. This is evidenced with the aid of Scanning Electron Microscopy (SEM) images, X-ray diffraction (XRD) and Energy Dispersive X-Ray Analysis (EDAX). It can be concluded from this study that the ettringite formation occurs even after the formation of pozzolanic compounds in lime-stabilized soil.
... Thyagaraj et al in 2014 compacted expansive soil in cylindrical mould and sequentially permeated with CaCl 2 and NaOH solutions through a hole in the centre filled with soil of high permeability. Results from this model test concluded that the pH of the soil increased to 12 which would be favourable for pozzolanic reactions to occur [16] . ...
Many relevant studies on lime stabilization have been done with regard to swell – shrink behaviour of expansive soils. Sequential lime mixing technique was also proven to be effective in limiting the swell shrink behaviour. But, strength and deformation are generally the most important parameters in assessing the effect of soil stabilization in pavement and other geotechnical practices. Therefore, the impact of these modification techniques has to be studied in terms of unconfined compressive strength of lime-treated soft clays. Such studies would definitely imbibe confidence in the practitioners to take up these advanced stabilization techniques which would in turn make our designs more robust and safer. In this regard, the current investigation is taken up to examine the efficiency of lime precipitation technique by sequential mixing of sodium hydroxide (NaOH) and calcium chloride (CaCl2). The lime precipitated in expansive soil is likely to change the basic properties by short term modification reaction and long term pozzolanic reactions between soil and lime. In expansive soils, Initial Consumption of Lime (ICL) was established based on the experiment proposed by Eades and Grimm. All the laboratory tests were done by maintaining these moisture and compaction conditions. Lime precipitation was employed on the mixes and its time dependent impact on physico-chemical behaviour of expansive soil and formation of various cementation products were studied. The study discusses the effect of these reactions on Particle size, Unconfined Compressive Strength (UCS) and California baring ratio (CBR). The soil-lime modification reactions had significant impact on the index properties and Particle size of the expansive soil. Due to strong short time modification reactions and long term pozzolanic reactions, a notable increase in the CBR and UCS values of the expansive soil was observed. © 2018, Indian Journal of Public Health Research and Development. All rights reserved.
... Then the secondary step is to control the problems posed by expansive soils with some innovative techniques available for stabilization. Among all these techniques, the preferable solutions for deeper soil stabilization is column techniques [5][6][7]. Some of the traditional columns techniques such as Lime-slurry injection, Granular piles, Lime columns, Fly ash columns have been suggested for mitigating swelling or heave problems [1,8,9]. ...
EPS geofoam is an excellent material for building road embankments on very soft soils, in slope stabilization, for reducing earth pressures acting on rigid structures, etc. Expansive soils give major challenges to geotechnical engineers because of high swelling and shrinkage characteristics that may severely damage the lightly loaded structures. Limited studies are available for the possible use of EPS geofoam for the reduction of vertical swelling of expansive soils. Columns techniques are preferable for deep stabilization of highly problematic soil. The use of compressible inclusion such as EPS geofoam column technique can be used to control the swelling potential of expansive soils. In this paper, an attempt has been made to study the effectiveness of EPS geofoam columns to control the vertical swelling of expansive soil with and without inclusions. For this study, EPS specimen with bulk density of 12 kg/m3 (EPS12) was chosen and column diameters were varied to study the effect of area replacement ratio (Ar) on swelling characteristics. Laboratory swell tests have been carried out on statically compacted swelling clay with and without EPS geofoam columns (EPSC) with varying diameter. Tests results show that there is a reduction in the vertical swelling of soil with the inclusion of EPSC when compared to the soil without inclusion. Also with the increase in Ar of EPSC, there is significant reduction in the swell potential of the soil.
... They used geosynthetic reinforcements, both geogrids and geotextiles, to minimize the development of longitudinal cracks in the pavements. The effect of using lime and cement deep soil mixing to reduce the heave and shrinkage of expansive subsoil underlying pavements studied by [5] .They concluded that the potential of the deep soil mixing treatment to decrease the shrink-swell related movements from expansive subsoil of moderate depths.Lime slurry technique in desiccated state used to study the efficiency of in-situ stabilization of expansive soil [6] , they noticed a considerable decrease in swelling potential and increased in the unconfined compressive strength of the treated soil. The present research is devoted to investigate the effect of drying on both undisturbed and remolded samples on the swelling at different periods ,and the effect of remolding on the undisturbed expansive soil samples also investigated at different drying periods .The research also studied the effect on the mineralogical compositions , Atterberg limits and linear shrinkage when adding cement dust as a new additive to reduce swellings. ...
The effect of drying and remolding on undisturbed expansive soil samples were investigated at different periods. The results showed that the swelling potentials for remolded samples were higher than those for undisturbed samples for different periods of testing. The results also showed that final swells and swell pressures increased as the initial moisture contents decrease for both remolded and undisturbed samples. The swelling potential increased as the initial dry density increases for both remolded and undisturbed expansive soil samples, and vice versa The cement dust used as a new additive material to decrease the swelling potential of the expansive soil. The results showed that the plasticity index, linear shrinkage, and clay minerals decreased with increasing cement dust percentage, where 50% of the montmorillonite disappeared after treatment the soil with 5% cement dust. The effect of cement dust columns on the swelling potential of the soil also studied extensively. The cement dust columns were embedded in the middle of the expansive soils using CBR mould .The results showed that the swelling potential decreased with increasing number of cement dust columns and when increasing the diameter of the cement dust columns ,a distinctive decrease in the swelling potentials were recorded. When decreasing the densities and increasing the diameters of cement dust columns resulted in decreasing the swelling potentials of the expansive soil. The swelling of the expansive soil been decreased when increasing the number of reinforced and non-reinforced cement dust columns. The swelling potentials showed distinctive decrease when the lengths of the reinforced cement dust columns increased.
The challenge posed by weak soil, characterized by low bearing capacity and shear strength, is significant in civil engineering, impacting road construction, structural foundations, and irrigation systems. Recycling non-biodegradable waste, especially glass waste, presents a promising solution for environmental sustainability and cost-effectiveness in construction. This study aims to improve the geotechnical properties of weak soils by stabilizing them with Waste Glass Powder (WGP) and exploring novel construction applications. The experimental investigations determined the optimal incorporation of glass powder into soil samples, ranging from 2% to 10% by dry weight. Geotechnical tests, including sieving analysis, Atterberg limits determination, California Bearing Ratio (CBR) tests, and Unconfined Compressive Strength (UCS) assessments, were conducted to assess the effect of glass powder addition. At a 10% glass powder content, the Plasticity Limit (PL), Liquid Limit (LL), and Plasticity Index (PI) were 18.4%, 33.9%, and 15.5%, respectively. The addition of glass powder significantly improved CBR values, reaching peaks of 10.5% (soaked CBR) and 22.3% (unsoaked CBR). Moreover, UCS increased to 135.6 kN/m2 with 8% glass powder, decreasing slightly to 120.8 kN/m2 with 10% glass powder. These findings highlight waste glass as a viable additive for enhancing the engineering properties of weak soils, promoting sustainable construction practices.
In-situ deep stabilization of expansive soil deposits is commonly carried out using lime piles and lime slurry injection. Recent research demonstrated the stabilization of expansive soils using lime column technique, and more recently the lime precipitation technique has emerged as the viable choice for stabilization of expansive soils. Comparison of these techniques in stabilizing the expansive soils provides a better understanding on the stabilization mechanisms and their advantages and limitations. Therefore, this paper brings out the relative efficacy of different lime treatment techniques in stabilizing the expansive soils. To achieve this objective, the laboratory model tests were carried out in expansive soil using lime pile and lime precipitation techniques in a compacted state, and lime slurry technique in a desiccated state from a central hole of diameter, d. The lime precipitation was achieved by sequential permeation of 46.2% calcium chloride and 33.3% sodium hydroxide solutions through a central hole in the compacted expansive soil. After 30 days of curing in the test moulds, the undisturbed soil specimens were collected for evaluation of the changes in physico-chemical, index and engineering properties. The experimental results reveal that the treatment is effective in stabilizing the expansive soil up to a radial distance of 0.8d from the central hole in case of lime pile treatment, whereas the lime slurry treatment up to a radial distance of 1.5d and lime precipitation treatment up to a radial distance of 2.5d. The experimental findings were supported with scanning electron microscopic images and energy dispersive X-ray spectroscopy analysis.
Sequential permeation of calcium chloride and sodium hydroxide solutions into the soil mass leads to the formation of lime in the in-situ soil mass owing to chemical reactions. Previous studies have demonstrated that the lime precipitation modifies the expansive soil properties both by lime modification and pozzolanic reactions. However, the independent contributions of either calcium chloride solution or sodium hydroxide solution in stabilizing the expansive soil are not known. Therefore, an attempt is made in the present investigation to examine the relative efficiencies of calcium chloride solution, sodium hydroxide solution and lime precipitation in stabilizing the expansive soil by comparing the physico-chemical and index properties, oedometer swell potentials and unconfined compressive strength of treated specimens. The present investigation also brings out the relative efficiencies of hydrated lime and precipitated lime in stabilizing the expansive soil. The experimental results showed that treating the expansive soils with calcium chloride and sodium hydroxide solutions independently promoted only the short-term reactions whereas the sequentially treating the expansive soil with calcium chloride and sodium hydroxide solutions resulted in the formation of lime precipitation, which could mobilize both short-term lime-modification reactions and long-term soil-lime pozzolanic reactions.
The presence of soft soils under the foundations in many geotechnical projects, including the construction of railroads, causes irreparable damage. For this purpose extensive studies have been conducted to improvement physical and mechanical properties of this soils. In this study the stabilization of soft clay was investigated with Lime and silica-fume. In this regard, the pozzolanic activity and the information obtained from the consolidation test, the optimal percentage of additives in the stabilized soil were determined and the behavior of soft soils was analyzed before and after stabilization by consolidation test. The tests results show that pozzolanic activity causes the formation of calcium silicate hydrate (C-S-H) and calcium alumina hydrate (C-A-H) gel, which results are increasing resistance and decreasing void ratio. By adding 0,10,20 and 30% by weight, lime and the mixture of lime and silica-fume with 21 curing days, was observed with an increase in lime and silica-fume up to 30% by weight the settlement decreases more than 700%. Overall, the results of this study indicate that silica-fume can be a suitable substitute for lime in stabilization of soft soils, which will help to reduce operating cost and in addition save the environment.
Sequential permeation of calcium chloride and sodium hydroxide solutions into the soil mass leads to
the formation of lime in the in-situ soil mass owing to chemical reactions. Previous studies have
demonstrated that the lime precipitation modifies the expansive soil properties both by lime
modification and pozzolanic reactions. However, the independent contributions of either calcium
chloride solution or sodium hydroxide solution in stabilizing the expansive soil are not known.
Therefore, an attempt is made in the present investigation to examine the relative efficiencies of
calcium chloride solution, sodium hydroxide solution and lime precipitation in stabilizing the
expansive soil by comparing the physico-chemical and index properties, oedometer swell potentials
and unconfined compressive strength of treated specimens. The present investigation also brings
out the relative efficiencies of hydrated lime and precipitated lime in stabilizing the expansive soil.
The experimental results showed that treating the expansive soils with calcium chloride and sodium
hydroxide solutions independently promoted only the short-term reactions whereas the sequentially
treating the expansive soil with calcium chloride and sodium hydroxide solutions resulted in the
formation of lime precipitation, which could mobilize both short-term lime-modification reactions and
long-term soil-lime pozzolanic reactions.
The paper examines the role of physico-chemical factors in the consistency limits and compressibility behavior of kaolinitic soils and montmorillonitic soils of residual origin. The liquid limit, equilibrium void ratio at a given load (in the oedometer test) and compression index values of the kaolinitic soils in the remolded state correlate well with the shrinkage limit values, which in turn are a function of the clay fabric. The corresponding engineering properties of the remolded montmorillonitic soils correlate well with the exchangeable sodium content that reflects a soil’s potential to develop diffuse ion layer.
Oedometer tests with undisturbed samples highlight the role of clay mineralogy in the engineering behavior of residual soils; on inundation with water under a nominal pressure, the kaolinitic soils exhibit no volume change while the montmorillonitic soils exhibit a notable swell. Oedometer tests with undisturbed samples also showed that besides the physico-chemical factors, the in-situ moisture content, density and degree of saturation have an important bearing on the void ratio sustained by the soils at a given stress level.
Excessive volume changes of expansive soil cause severe damage to civil structures, which costs billions of dollars in annual repairs. In this paper, the optimum ratio of lime to soil weight to maximise the efficiency of lime columns as a technique to reduce the swelling of expansive soil is investigated. A new technique to further enhance the efficiency of the lime columns technique in reducing soil swelling is also investigated, namely reinforced lime columns. The new technique involves reinforcing the lime columns using reinforcement bars attached to the foundation of the structure. The experimental study involved laboratory-scale tests of expansive soil beds treated with lime columns supporting model foundations. The experimental results showed that the optimum lime content is 6% (by weight) of the soil within the column. It was found that the lime columns technique minimised the swelling of the expansive soil by 33%. In the meantime, the reinforced lime columns reduced the swelling of an identical soil bed by 69%. The results also showed that the swelling of the expansive soil decreased with an increase in the ratio Lcol/Dsoil (the ratio of the length of lime columns to the depth of expansive soil).
This paper examines the efficiency of 75 mm diameter lime piles in altering the physico-chemical and engineering properties of a compacted expansive soil. Calcium and hydroxyl ions from the lime pile migrated into the surrounding soil mass and increased the soil pH and pore salinity. The increase in soil pH from lime migration could not increase the soil pH to levels (⩾ 12) that were conducive for pozzolanic reactions. The increase in soil pH, however, increased the exchangeable calcium ion content of the soil by apparently imparting additional negative charge to the clay particle edges. Lime modification reactions due to increased pore salinity and exchangeable calcium ions suppressed the plasticity index and swell potential, and slightly increased the unconfined compressive strength of the compacted expansive soil.
Dans cet exposé, nous examinons la capacité des piles de chaux de 75 mm de diamètre ont de à changer les propriétés physico-chimiques et industrielles d'un sol expansif compacté. Les ions de calcium et d'hydroxyle présents dans la pile de chaux migrant dans la masse du sol avoisinant environnant, augmentant son pH et la salinité des pores. L'augmentation du pH du sol causée par la migration de chaux ne peut atteindre des niveauzx (⩾ 12) qui favorisent favorisant des réactions pouzzolani-ques. Cependant, l'augmentation du pH du sol augmente la teneur de celui-ci en ions de calcium échangeables en apportant apparemment une charge négative supplémentaire sur les bords des particules d'argile. Les réactions de modification de la chaux dues à une plus grande salinité de pores et aux ions de calcium échangeables suppriment l'indice de plasticité et le potential de gonflement et augmentent légèrement la résistance à la compression non confinée du sol expansif compact.
The paper reports the mechanisms controlling the Atterberg limits and compressibility characteristics of bentonite homoionized with a series of monovalent, divalent and trivalent cations. An increase in cationic valency reduces the liquid limit and the compressibility of the clay material, while an increase in the hydrated ionic radius (for a constant valency) increases the liquid limit and compressibility. The size effect is more pronounced for the monovalent bentonites than for the divalent and trivalent clays. The influence of ionic size is explained qualitatively by the Stern model.
Lime slurry and lime pile techniques are viable choices for in-situ stabilisation of expansive soil deposits. This paper reports the results of a laboratory study on in-situ chemical stabilisation of an expansive soil that permeated lime slurry through an artificially desiccated expansive soil specimen. The soil was desiccated in the laboratory to induce shrinkage cracks in the compacted expansive soil. The shrinkage cracks greatly assisted migration of lime slurry in the expansive soil mass. The efficiency of lime slurry in chemically stabilising the desiccated expansive soil was investigated by comparing the physico-chemical properties and engineering properties of the treated soil with those of the natural soil specimen at two radial distances. Experimental results indicated that migration of lime slurry through the desiccated soil promoted strong lime modification and pozzolanic reactions in the soil mass. The strong soil-lime reactions rendered the soil less plastic, reduced the swell magnitude, and increased the unconfined compressive strength of the lime-slurry-treated specimens. Laboratory results indicate that slurry application to soil deposits with shrinkage is effective, and that it may therefore be preferable to chemically stabilise soil deposits during the dry season.
Study to develop reliable means for predicting potential expansion characteristics of clays from classification test data is described; it is shown that well-defined relationship can be established between percentage of clay sizes present in soil, activity of clay, and percentage of swell under 1-psi surcharge of sample compacted at optimum water content to maximum density in Standard AASHO Compaction Test; charts developed from data.
Expansive clay soils have been encountered at the sites of structures throughout the western United States. Inasmuch as most of these structures are hydraulic, the normal difficulties encountered when expansive clays are present in the subgrade foundation are greatly magnified. As a result of some of the difficulties that have been experienced, considerable research testing has been undertaken so ·that expansive clays can be recognized and their potential swelling properties anticipated.
Today’s competitive construction industry is highly dependent on effective use of existing and innovative technologies. In many situations the key issue is not how to break through technological barriers but how to put existing concepts to the best possible use. Whereas the basic knowledge behind many developed techniques can be found in engineering textbooks, the complex issues related to know-how of analysis and design, construction techniques, and quality monitoring, developed based on regional experiences, have not been widely available to engineers working in different countries. In a series of papers, the aim is to examine issues, concepts, and the latest advancements in research and development of deep soil mixing technology. The focus is on presenting basic concepts, various application areas, considerations for analysis and design, construction techniques, methods of quality control, and so on. A large number of case histories of deep mixing projects, applied in different countries, are collected...
Clay soils can be stabilised at depth using the distinctly different techniques of lime columns, lime piles and lime slurry injection. The three processes are described and their application to new, failing and failed slopes is discussed. Both short-term and long-term stability are assessed, with particular reference to porewater pressure and volume changes. The results of a preliminary programme of tests to examine strength gain mechanisms in clay surrounding lime piles are presented. The paper concludes that the techniques have considerable potential, but that a good understanding of the processes taking place as a result of each method is necessary for design. -Authors
Soft clays of low strength and high compressibility are located in many coastal and offshore areas, and they cause several foundation problems for the structures resting on these marine deposits. The necessity to construct engineering structures on these deposits is a challenging task for the civil engineers and there is a need to improve the engineering behavior of these clays. The present investigation deals with an experimental work carried out in the laboratory using lime column and lime injection techniques to stabilize a marine clay. The formation of new reaction products due to soil-lime reactions was studied using XRD and SEM techniques. The results indicated the formation of cementitious compounds such as calcium silicate hydrate (CSH) and calcium aluminate hydrate (CAH) in different lime treated soil systems and it has been observed that their formation was not affected by the presence of sea water. There is a considerable improvement in the physical properties of the lime treated soil systems, and the test results have established that both the lime column and lime injection techniques can be successfully used to improve the behavior of soft marine clayey deposits.
Today's competitive construction industry is highly dependent on effective use of existing and innovative technologies. In many situations the key issue is not how to break through technological barriers but how to put existing concepts to the best possible use. Whereas the basic knowledge behind many developed techniques can be found in engineering textbooks, the complex issues related to know-how of analysis and design, construction techniques, and quality monitoring, developed based on regional experiences, have not been widely available to engineers working in different countries. In a series of papers, the aim is to examine issues, concepts, and the latest advancements in research and development of deep soil mixing technology. The focus is on presenting basic concepts, various application areas, considerations for analysis and design, construction techniques, methods of quality control, and so on. A large number of case histories of deep mixing projects, applied in different countries, are collected to portray various functions of deep mixing; along with references to exemplify the current practice and the present understanding of the technology. This first paper emphasizes basic concepts, definitions, classifications, and historical developments related to deep mixing technology around the world.
Lime treatment as a mix-in-place technique has been widely and successfully used around the world to improve weak soils. Novel techniques using lime are now being developed. One such technique is the use of lime piles to stabilize shallow slopes. Recent research has investigated the reaction mechanisms associated with lime pile stabilization. This paper describes excavation work undertaken at two sites where previously lime piles had been installed to prevent further movement of a failing slope. Laboratory tests undertaken on the retrieved material are also presented and discussed in terms of whether/how the reaction mechanisms have improved the stability of the slope. Results suggested several ground improvement mechanisms, some of which could only be relied upon in the short term. Since installation of the lime piles at both sites no further movements have been recorded, suggesting that this method of stabilization has been successful.
Swelling of expansive soils and associated movements of foundations cause serious problems to many structures. With the existing expansive clays in Ankara, capital city of Turkey, some light buildings, road pavements and buried pipelines have shown some damage. To avoid such damage, prior to construction expansive clays may be stabilized. There has been little work concerning the stabilization of Ankara Clay and this was concentrated on the lime mixture technique. The main objective of this study was to investigate the performance of the lime column technique on laboratory-scaled models to improve the physical, swelling, strength and consolidation characteristics of this clay. The characteristics of the treated samples were determined in terms of distance to the column and curing period. In general, the results suggested that the most effective zone for the lime migration developed at a distance approximately twice the column diameter and a curing period of 28 days generally seemed to be sufficient. Application of the technique provided a gain in strength between 40 and 80% and resulted in an increase in pre-consolidation pressure and a decrease in the compressibility characteristics of the treated soils, depending on the distance to the lime column. Construction of the column caused a drastic reduction in swell pressure, between 40 and 75%.
This book provides a summary of the state-of-the-art of expansive soils and practical solutions based upon the author's experience. Part I discusses theory and practice, and summarizes some of the theoretical physical properties of expansive soils. It also discusses various techniques employed to found structures on expansive soils such as drilled pier foundation, mat foundation, moisture control, soil replacement, and chemical stabilization. Part II presents case studies. The author has found that few records are available on the cause of structural distress, their remedial measures, and more important, the degree of success after those measures have been completed.
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