Academic literature on the topic 'Lime Stabilized Soil'

This thesis presents the results of a series of undrained cyclic triaxial tests carried out on four lime-cement stabilized specimens and clay specimen. The shear resistance degradation rate of lime-cement column subjected to cyclic loading simulated from heavy truck was investigated based on stress-controlled test. The influence of lime and cement on the degradation rate was investigated by comparing the behavior of stabilized kaolin and unstabilized kaolin with similar initial condition. The results indicate an increase in degree of degradation as the number of loading cycles and cyclic strain increase. It is observed that the degradation index has approximately a parabolic relationship with the number of cycles. Generally adding lime and cement to the clay will increase the degradation index which means lower degree of degradation. The degradation parameter, t has a hyperbolic relationship with shear strain, but it loses its hyperbolic shape as the soil getting stronger. On the other hand, for unstabilized clay an approximate linear relationship between degradation index and number of cycles was observed and the degradation parameter has a hyperbolic shape with the increase number of cycles. It was also observed that the stronger the material was, the lesser pore pressure developed in the lime-cement stabilized clay.

PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO<br>CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO<br>Este estudo apresenta o comportamento de um solo arenoso estabilizado com cinzas obtidas através da incineração de Resíduo Sólido Urbano (RSU) e cal. Através de um estudo experimental, objetiva-se avaliar a aplicabilidade de misturas solo-cinza e solo-cinza volante-cal em obras geotécnicas como, por exemplo, camadas de aterros sanitários, aterros sobre solos moles e estabilização de taludes. Para isso, foram realizados ensaios de caracterização física, química e mecânica (ensaios triaxiais CID) para os materiais envolvidos. Para as misturas solo-cinza volante-cal, adicionou-se 3 porcento de cal em substituição ao peso seco das cinzas. Foram avaliadas as influências do teor de cinza (30 e 40 porcento) e tipo de cinza (volante - CV e fundo - CF), bem como o tempo de cura (0, 60 e 90 dias) para misturas com cinza volante e cal. Os resultados mostram que tanto as misturas com CV, como CF, apresentam resultados satisfatórios. Para ambas as cinzas, as porcentagens de 30 e 40 porcento apresentaram resultados similares, podendo-se adotar o valor de 40 porcento como teor ótimo, uma vez que proporciona a utilização de uma maior quantidade de resíduo. Comparando-se as cinzas, a CF apresentou resultados mais satisfatórios que a CV. Para as misturas com cura, observou-se que no tempo de 60 dias o material sofreu um maior ganho de resistência. Foram utilizados dois métodos de moldagem de corpo de prova para o ensaio com cura, obtendo-se melhor resultado para o método onde a cura era realizada em um corpo de prova pré-moldado. Portanto o uso das cinzas de RSU em mistura com este tipo de solo se mostra satisfatório, uma vez que apresentou um bom comportamento, contribui com o menor consumo de material natural e proporciona uma destinação ambientalmente correta deste resíduo.<br>This study presents the behavior of a sandy soil stabilized with municipal solid waste ash, and lime. In order to evaluate the applicability of mixtures soil-ash and soil-fly ash-lime for using in geotechnical projects as layers of landfills, embankment on soft soils and slope stability, an experimental campaign is presented. Thus, physical, chemical and mechanical (isotropically consolidated-drained triaxial test) characterization tests were performed for each material and mixtures. It was used 3 percent of lime in the mixtures soil- fly ash-lime, being added in replacement to the dry weight of fly ash. Were evaluated the influence of ash content (30 and 40 percent), type of ash (fly ash and bottom ash) and curing time (0, 60 and 90 days) for mixtures containing fly ash and lime. The results have shown that mixtures with both kinds of ashes present a satisfactory behavior, increasing or maintaining the shear strength parameters similar to the pure material. For both kinds of ashes the variation of the content has not provided significant changes in the strength parameters, therefore, 40 percent can be considered as best content, once it provides a bigger destination of the residue. Comparing fly and bottom ash, the last has presented better results than fly ash. For mixtures with lime and cure, it has been observed better results for 60 days of cure, with greater gain of strength. Two molding methods have been used for preparing the mixture specimen, being obtained a better result with pre modeled specimen. Therefore, the use of municipal solid waste ash for stabilizing this kind of soil for using in the cited works, could minimize the current problems of waste disposal, contribute with the reduction of consumption of natural resources and give a noble use for this material.

Made available in DSpace on 2016-06-02T20:00:47Z (GMT). No. of bitstreams: 1 4872.pdf: 3473885 bytes, checksum: 1bd5a5d73dae0ecc0bb5b60b52acba6b (MD5) Previous issue date: 2012-11-27<br>In view of the lack of basic infrastructure in Brazilian cities, especially in regard to paving networks, it is of fundamental importance a study to ascertain the geological characteristics of the materials available and their potential use as pavement layer after incorporation of additives. This thesis aims at determining, in the laboratory, the mechanical results of soiladditive mixture, in order to evaluate the structural performance of chemically stabilized tropical soils. It also brings, specific objectives, comparing traditional additives - cement and lime - with another additive available in the brazilian market; analyzing the possibility of using these stabilized soils in urban pavement layers and obtaining reference results that may provide subsidies for pavement designers. This research develops from the collection of four (4) soil samples at different points in São Carlos/SP, with whom has been conducted a series of tests: California Bearing Ratio, Expansion and Compression Test. There was an evaluation of soils by determining the mechanical properties of the mixed soil and additive, in terms of carrying capacity, simple compression and expansion. The results were obtained after compression of the mixture in the test specimens and the use of standardized testing methodologies. After a long series of laboratory tests developed for each sample, a critical analysis of structural performance, primarily in its natural condition, then with the structural behavior of each of them, after the incorporation of additives. Research has shown that the best structural behavior of all samples collected in the different conditions of stabilization occurred with the sample ST-03 which, stabilized with 6% cement, obtained in laboratory satisfactory performance for use as the base layer of pavement.<br>Em vista da carência de infra-estrutura básica nas cidades brasileiras, principalmente no que se refere às redes de pavimentação, faz-se de fundamental importância um estudo que permita conhecer as características geológicas dos materiais disponíveis e as suas possibilidades de utilização como camada de pavimento após a incorporação de aditivos. Esta dissertação tem como objetivo principal determinar, em laboratório, os resultados mecânicos da mistura soloaditivo, a fim de se avaliar o desempenho estrutural de solos tropicais estabilizados quimicamente. Traz ainda, como objetivos específicos, comparar os aditivos tradicionais - cimento e cal - com uma opção de aditivo disponível no mercado brasileiro; analisar a possibilidade de utilização desses solos estabilizados em camadas de pavimentos urbanos e obter resultados de referência que venham a fornecer subsídios aos projetistas de pavimento. Esta pesquisa desenvolve-se a partir da coleta de 4 (quatro) amostras de solo em diferentes pontos do município de São Carlos/S.P., com as quais se realizou uma série de ensaios de Capacidade de Suporte (CBR), Expansão (EXP.) e de Resistência a Compressão Simples (RC). Fez-se a avaliação dos solos tropicais através da determinação das propriedades mecânicas das misturas de solo e aditivo, em termos de capacidade de suporte, expansão e compressão simples. Os resultados foram obtidos após a compactação da mistura, em corpos de prova e com o emprego das metodologias de ensaio normalizadas. Após uma larga série de ensaios de laboratório, desenvolveu-se, para cada amostra, uma análise crítica do desempenho estrutural, primeiramente, em sua condição natural e, depois, no comportamento estrutural de cada uma delas, após a incorporação dos aditivos supracitados. A pesquisa demostrou que o melhor comportamento estrutural de todas as amostras coletadas, nas diversas condições de estabilização, ocorreu com a amostra ST-03 que, estabilizada com 6% de cimento, obteve em laboratório desempenho satisfatório para emprego como camada de base de pavimento.

Modification of black cotton soils by chemical admixtures is a common method for stabilizing the swell-shrink tendency of expansive soils. Advantages of chemical stabilization are that they reduce the swell-shrink tendency of the expansive soils and also render the soils less plastic. Among the chemical stabilization methods for expansive soils, lime stabilization is most widely adopted method for improving the swell-shrink characteristics of expansive soils. Lime stabilization of clays in field is achieved by shallow mixing of lime and soil or by deep stabilization technique. Shallow stabilization involves scarifying the soil to the required depth and lime in powder or slurry form is spread and mixed with the soil using a rotovator. The use of lime as deep stabilizer has been mainly restricted to improve the engineering behaviour of soft clays Deep stabilization using lime can be divided in three main groups: lime columns, lime piles and lime slurry injection. Lime columns refer to creation of deep vertical columns of lime stabilized material. Lime piles are usually holes in the ground filled with lime. Lime slurry pressure injection, as the name suggests, involves the introduction of a lime slurry into the ground under pressure. Literature review brings out that lime stabilization of expansive clays in field is mainly performed by mixing of lime and soil up to shallow depths. The use of lime as deep stabilizer has been mainly restricted to improve the engineering behaviour of soft clays. Use of lime in deep stabilization of expansive soils however has not been given due attention. There exists a definite need to examine methods for deep stabilization of expansive soils to prevent the deeper soil layers from causing distress to the structures in response to the seasonal climatic variations. In addition, there exists a need for in-situ soil stabilization using lime in case of distressed structures founded on expansive soil deposits. The physical mixing of lime and soil in shallow stabilization method ensures efficient contact between lime and clay particles of the soil. It however has limitation in terms of application as it is only suited for stabilization of expansive soils to relatively shallow depths. Studies available have not compared the relative efficiency of the lime pile technique and lime-soil mixing method in altering the physico-chemical, index and engineering properties of expansive black cotton soils. To achieve the above objectives laboratory experiments are performed that study: 1. the efficacy of lime piles in stabilizing compacted black cotton soil specimens from Chitradurga District in Karnataka. The efficiency of lime piles in chemically stabilizing the compacted black cotton soil mass was investigated as a function of: a)amount of lime contained in the lime pile b)radial migration of lime from the central lime pile c)migration of lime as a function of soil depth 2. the relative impact of the lime pile technique and lime-soil mixing method in altering the physico-chemical, index and engineering properties of expansive black cotton soil. The organization of this thesis is as follows After the first introductory chapter, a detailed review of literature performed towards highlighting the need to examine stabilization of expansive soils using lime pile technique is brought out in Chapter 2. Chapter 3 presents a detailed experimental programme of the study. 25 mm and 75 mm diameter lime piles were installed in the compacted soil mass to study the influence of amount of lime contained in the lime pile on the soil properties. The amount of quick lime contained in the 25 mm and 75 mm lime piles corresponded to 1 % and 3 % by dry weight of the soil mass respectively. Radial and vertical migration of lime from the central lime pile was examined by sampling soil specimens at different radial distances from the central lime pile and at different depths of soil sample. At a given depth and radial distance, migration of lime was estimated by comparing the exchangeable cation composition, pH and pore salinity of the treated soil with that of the natural (untreated) black cotton soil specimen. Alterations in the soil engineering properties at a given depth and radial distance were evaluated by comparing the index properties, swell potential and unconfined compressive strength of the lime pile treated soil specimen with those of the untreated specimen. To compare the relative efficiency of lime mixing and lime pile technique in altering the swelling behaviour of black cotton soil, batches of black cotton soil specimens were treated with 1 % and 3 % quick lime on dry soil weight basis. The compacted soil-lime mixes were cured at moisture contents of 31-34 % for a period of 10 days. The physico-chemical, index and engineering properties of the 1 % lime mixed specimens are compared with those of the 25 mm lime pile treated specimens. The properties of the 3 % lime mixed soil specimens are compared with those of the 75 mm lime pile treated specimens. Chapter 4 examines the efficacy of lime piles in stabilizing compacted black cotton soil specimens from Chitradurga District in Karnataka. Experimental results showed that controlling the swell potential of deep expansive soil deposits is possible by the lime pile technique. Treatment with lime pile caused migration of dissociated calcium and hydroxyl ions into the surrounding soil mass. In case of 25 mm lime pile, the experimental setup allowed measurement of migration of lime up to three times the lime pile diameter. In case of 75 mm lime pile, the experimental setup allowed measurement of migration of lime up to 1.6 times pile diameter. In both experiments, migration of lime was also uniform through out the soil depth of 280 mm. Migration of calcium and hydroxyl ions increased the pore salinity and pH of the treated soil mass. The increase in pH caused clustering of additional exchangeable calcium ions at the negative clay particle edges. The increased pore salinity and exchangeable calcium ions reduced the diffuse ion layer thickness that in turn suppressed the plasticity index and the swell potential of the compacted expansive soil. The laboratory results hence bring out that lime pile treatment in the field can substantially reduce the swell potential of the soil at least to a radial extent of 2 to 3 times the lime pile diameter. The 75 mm lime pile contained lime content in excess of the initial consumption of lime (ICL) value of the black cotton soil - namely 2.6 %. Laboratory results showed that migration of hydroxyl ions even from the 75 mm pile could not elevate the soil pH to levels required for soil-lime pozzoIonic reactions (pH ≥12). The very low solubility of lime in water (< 1 g/litre) and the impervious nature of the black cotton soil are considered to have impeded efficient interactions between lime and soil in course of treatment of the expansive soil with lime piles. Absence of soil-lime pozzolonic reactions precluded the formation of cementation compounds in the lime pile treated soil specimens. Cementation compounds formed by the soil-lime pozzolonic reactions are responsible for the much higher strengths of lime stabilized soils. Consequently, treatment with 25 mm pile had no impact on the unconfined compressive strength of the black cotton soil. Comparatively, treatment with 75 mm lime pile slightly increased the strength of the treated soil due to increased inter-particle attraction and particle flocculation. Chapter 5 compares the relative efficiency of the lime pile technique and lime-soil mixing method in altering the physico-chemical, index and engineering properties of expansive black cotton soil. Experimental results showed that mixing of soil and lime promote stronger chemical interactions between lime released hydroxyl ions and clay particles than that achieved by diffusion of lime from a central lime pile. The more alkaline pH of the lime mixed soil specimens rendered the clay particle edges more negative. Consequently, more calcium ions were adsorbed at the clay particle edges of the lime mixed soil specimens imparting them higher exchangeable calcium contents than the lime pile treated soil specimens. Also, at 3 % lime addition, the pH of the lime-mixed soil was sufficiently high (in excess of 12) to cause dissolution of silica and alumina from the clay lattice necessary for the formation of cementation compounds. The stronger lime modification reactions plus the lime-soil pozzolonic reactions (applicable for soil treated with lime content greater than ICL value) achieved by the lime mixing technique rendered the expansive soil much less plastic, much less expansive and much stronger than the lime pile treated specimens. The results of the laboratory study hence suggest that if a choice exists in the field between conventional method of spreading-mixing-compacting of soil-lime mixes and treating the ground with lime piles, the former technique should be adopted because of its greater efficacy in stabilizing the expansive soil. Chapter 6 summarizes the findings of the study.

Modification of black cotton soils by chemical admixtures is a common method for stabilizing the swell-shrink tendency of expansive soils. Advantages of chemical stabilization are that they reduce the swell-shrink tendency of the expansive soils and also render the soils less plastic. Among the chemical stabilization methods for expansive soils, lime stabilization is most widely adopted method for improving the swell-shrink characteristics of expansive soils. Lime stabilization of clays in field is achieved by shallow mixing of lime and soil or by deep stabilization technique. Shallow stabilization involves scarifying the soil to the required depth and lime in powder or slurry form is spread and mixed with the soil using a rotovator. The use of lime as deep stabilizer has been mainly restricted to improve the engineering behaviour of soft clays Deep stabilization using lime can be divided in three main groups: lime columns, lime piles and lime slurry injection. Lime columns refer to creation of deep vertical columns of lime stabilized material. Lime piles are usually holes in the ground filled with lime. Lime slurry pressure injection, as the name suggests, involves the introduction of a lime slurry into the ground under pressure. Literature review brings out that lime stabilization of expansive clays in field is mainly performed by mixing of lime and soil up to shallow depths. The use of lime as deep stabilizer has been mainly restricted to improve the engineering behaviour of soft clays. Use of lime in deep stabilization of expansive soils however has not been given due attention. There exists a definite need to examine methods for deep stabilization of expansive soils to prevent the deeper soil layers from causing distress to the structures in response to the seasonal climatic variations. In addition, there exists a need for in-situ soil stabilization using lime in case of distressed structures founded on expansive soil deposits. The physical mixing of lime and soil in shallow stabilization method ensures efficient contact between lime and clay particles of the soil. It however has limitation in terms of application as it is only suited for stabilization of expansive soils to relatively shallow depths. Studies available have not compared the relative efficiency of the lime pile technique and lime-soil mixing method in altering the physico-chemical, index and engineering properties of expansive black cotton soils. To achieve the above objectives laboratory experiments are performed that study: 1. the efficacy of lime piles in stabilizing compacted black cotton soil specimens from Chitradurga District in Karnataka. The efficiency of lime piles in chemically stabilizing the compacted black cotton soil mass was investigated as a function of: a)amount of lime contained in the lime pile b)radial migration of lime from the central lime pile c)migration of lime as a function of soil depth 2. the relative impact of the lime pile technique and lime-soil mixing method in altering the physico-chemical, index and engineering properties of expansive black cotton soil. The organization of this thesis is as follows After the first introductory chapter, a detailed review of literature performed towards highlighting the need to examine stabilization of expansive soils using lime pile technique is brought out in Chapter 2. Chapter 3 presents a detailed experimental programme of the study. 25 mm and 75 mm diameter lime piles were installed in the compacted soil mass to study the influence of amount of lime contained in the lime pile on the soil properties. The amount of quick lime contained in the 25 mm and 75 mm lime piles corresponded to 1 % and 3 % by dry weight of the soil mass respectively. Radial and vertical migration of lime from the central lime pile was examined by sampling soil specimens at different radial distances from the central lime pile and at different depths of soil sample. At a given depth and radial distance, migration of lime was estimated by comparing the exchangeable cation composition, pH and pore salinity of the treated soil with that of the natural (untreated) black cotton soil specimen. Alterations in the soil engineering properties at a given depth and radial distance were evaluated by comparing the index properties, swell potential and unconfined compressive strength of the lime pile treated soil specimen with those of the untreated specimen. To compare the relative efficiency of lime mixing and lime pile technique in altering the swelling behaviour of black cotton soil, batches of black cotton soil specimens were treated with 1 % and 3 % quick lime on dry soil weight basis. The compacted soil-lime mixes were cured at moisture contents of 31-34 % for a period of 10 days. The physico-chemical, index and engineering properties of the 1 % lime mixed specimens are compared with those of the 25 mm lime pile treated specimens. The properties of the 3 % lime mixed soil specimens are compared with those of the 75 mm lime pile treated specimens. Chapter 4 examines the efficacy of lime piles in stabilizing compacted black cotton soil specimens from Chitradurga District in Karnataka. Experimental results showed that controlling the swell potential of deep expansive soil deposits is possible by the lime pile technique. Treatment with lime pile caused migration of dissociated calcium and hydroxyl ions into the surrounding soil mass. In case of 25 mm lime pile, the experimental setup allowed measurement of migration of lime up to three times the lime pile diameter. In case of 75 mm lime pile, the experimental setup allowed measurement of migration of lime up to 1.6 times pile diameter. In both experiments, migration of lime was also uniform through out the soil depth of 280 mm. Migration of calcium and hydroxyl ions increased the pore salinity and pH of the treated soil mass. The increase in pH caused clustering of additional exchangeable calcium ions at the negative clay particle edges. The increased pore salinity and exchangeable calcium ions reduced the diffuse ion layer thickness that in turn suppressed the plasticity index and the swell potential of the compacted expansive soil. The laboratory results hence bring out that lime pile treatment in the field can substantially reduce the swell potential of the soil at least to a radial extent of 2 to 3 times the lime pile diameter. The 75 mm lime pile contained lime content in excess of the initial consumption of lime (ICL) value of the black cotton soil - namely 2.6 %. Laboratory results showed that migration of hydroxyl ions even from the 75 mm pile could not elevate the soil pH to levels required for soil-lime pozzoIonic reactions (pH ≥12). The very low solubility of lime in water (< 1 g/litre) and the impervious nature of the black cotton soil are considered to have impeded efficient interactions between lime and soil in course of treatment of the expansive soil with lime piles. Absence of soil-lime pozzolonic reactions precluded the formation of cementation compounds in the lime pile treated soil specimens. Cementation compounds formed by the soil-lime pozzolonic reactions are responsible for the much higher strengths of lime stabilized soils. Consequently, treatment with 25 mm pile had no impact on the unconfined compressive strength of the black cotton soil. Comparatively, treatment with 75 mm lime pile slightly increased the strength of the treated soil due to increased inter-particle attraction and particle flocculation. Chapter 5 compares the relative efficiency of the lime pile technique and lime-soil mixing method in altering the physico-chemical, index and engineering properties of expansive black cotton soil. Experimental results showed that mixing of soil and lime promote stronger chemical interactions between lime released hydroxyl ions and clay particles than that achieved by diffusion of lime from a central lime pile. The more alkaline pH of the lime mixed soil specimens rendered the clay particle edges more negative. Consequently, more calcium ions were adsorbed at the clay particle edges of the lime mixed soil specimens imparting them higher exchangeable calcium contents than the lime pile treated soil specimens. Also, at 3 % lime addition, the pH of the lime-mixed soil was sufficiently high (in excess of 12) to cause dissolution of silica and alumina from the clay lattice necessary for the formation of cementation compounds. The stronger lime modification reactions plus the lime-soil pozzolonic reactions (applicable for soil treated with lime content greater than ICL value) achieved by the lime mixing technique rendered the expansive soil much less plastic, much less expansive and much stronger than the lime pile treated specimens. The results of the laboratory study hence suggest that if a choice exists in the field between conventional method of spreading-mixing-compacting of soil-lime mixes and treating the ground with lime piles, the former technique should be adopted because of its greater efficacy in stabilizing the expansive soil. Chapter 6 summarizes the findings of the study.

Soil stabilisation is a useful civil engineering technique that enables the insitu material to be used as part of an engineered structure. Stabilised layers are used in road foundation; working platforms and for slope stabilisation and sea defences. Chemical stabilisation involves the use of a hydraulic binder (and sometimes additional pozzolans). Commonly, quicklime (CaO) or slaked-lime (Ca(OH)2) is used. On mixing into the ground, this reacts with the aluminosilicates of the clay fraction, reducing its overall water content and plasticity. Further additions increase the insitu pH. Above pH 10.4, the aluminosilicates become soluble in the pore solution. They are then able to form a range of insoluble mineral hydrates which constitute a cementitious matrix. This results in both an increase in mechanical strength and a decrease in dimensional stability. If the insitu material contains sulfur bearing mineralogies, these can react with the hydraulic binder and the aluminosilicates to form expansive minerals. If this occurs after the initial setting and hardening of the stabilised layer has occurred, it can lead to severe dimensional instability and mechanical weakening. This is termed sulfate heave and the principal agent of this heave is a hydrous calcium sulfoaluminate hydrate, ettringite (AFt). The fundamental processes of ettringite formation and associated expansion are little understood in stabilised soils. This research used a range of artificial sulfate bearing, lime stabilised blended soil samples subject to two immersion tests used for material suitability assessment in the UK. The physicochemical response (in terms of dimensional heave and mechanical weakening) was assessed as a function of soil composition and the environmental conditions imposed by the two immersion tests. The fundamental microstructure and phase composition was characterised using a range of analytical techniques (XRD, SEM-EDX, dTGA). The relationship between the observed macro-physical properties and underlying chemical environment and microstructure was explored. Key findings include that the mechanism of ettringite formation and expansion was found to be governed by the fundamental structure of the bulk clay. This explained the greater swell response of the kaolin based soils compared to those of the montmorillonite. The SEM-EDX analysis identified a primitive, Ca-rich, AFt phase termed ‘ball ettringite’, in stabilised soils. This has only relatively recently been reported in studies of cement mortars. Also, small amounts of sulfate in the bulk soil actually increase soil strength. It was suggested that the preferential formation of monosulfate (AFm) plays an important role in this mechanism. The introduction of water to the pore solution is key to the formation of ettringite. This was evidenced by X-Ray CT of the damage caused to soil specimens on immersion, as well as low angle XRD studies of the principal AFt peak. Based on the limited testing undertaken one of the immersion tests (European accelerated volumetic swell test, EN13286-49), appears to be more onerous than the other (UK CBR linear swell test, BS1924-2).