Lime-treated Soil Research Articles

Lime Stabilization of Tropical Soil for Resilient Pavements: Mechanical, Microscopic, and Mineralogical Characteristics.

Lime stabilization is a sustainable technique due to its use of local materials, increased durability, reduced maintenance, and improved resistance to water action. This paper examines the impact of lime stabilization on the mechanical, microscopic, and mineralogical properties of a tropical soil. Two types of lime, calcitic and dolomitic, were tested at 3% and 5% by weight. Compressive, indirect tensile and flexural test results and statistical analysis revealed that calcitic lime mixtures had higher strength and stiffness, whereas dolomitic lime mixtures exhibited greater deformability with higher tensile strain at break. Scanning electron microscopy indicated that the soil's porous matrix closed within 7 days for both lime types due to flocculation, with increased matrix interlocking over time. The calcitic lime mixture developed a more closed matrix compared to the dolomitic lime, which showed weaker cementing. X-ray diffraction analysis indicated higher consumption of clay minerals and a notable reduction in calcium hydroxide peaks in the lime-treated soils. The study concludes that calcitic lime provides better pavement performance for stabilizing the soil, enhancing its engineering properties while also being sustainable by reducing the need for raw material extraction and improving resilience to climate-related issues such as floods.

Experimental study on improving the performance of imitation earthen site soil in carbon dioxide environment

This study aims to explore the performance of lime-treated soil for repairing the lime soil of the earthen city wall of Kaifeng and to standardize the construction technology of lime-treated soil. The research comprehensively considered factors such as carbonation time, lime particle size, aging conditions, and lime content, and conducted various tests and analyses including triaxial mechanical properties, surface crack analysis, particle size distribution, pH measurement, composition analysis, and electron microscopy on different samples. The results indicate that the significant effect of high-concentration CO2 carbonation enhances the chemical reactions of lime soil, and an appropriate carbonation process can strengthen the bonding and density between soil particles. Under the maintenance condition of 5 % CO2, with increasing carbonation time, the crack ratio, average crack length, and average crack width of the samples decreased. Cohesion and internal friction angle of the samples exhibited an initial increase followed by a decrease, while shear strength of the samples increased by 22.93 %–75.09 %. The lime particle size has a critical impact on the formation of cracks in lime soil. With increasing lime particle size, the crack ratio, average crack length, and average crack width of the samples increased. Cohesion and internal friction angle of the samples gradually increased with increasing lime content. The increase in crack ratio, average crack length, and average crack width during natural curing of lime-treated soil samples was proportional to the lime content. Appropriate carbonation time, smaller lime particle size, and curing conditions with 5 % CO2 contribute to improving the particle size distribution of lime-treated soil samples, reducing surface cracks, and enhancing performance. However, prolonged carbonation may lead to larger lime particle size, resulting in rough and loose particles, disorganized arrangement of CaCO3 crystals, and the inability to form a cross-linked network skeleton, causing a reduction in shear strength of the samples. These research findings provide important theoretical basis and construction technology guidance for the application of lime-treated soil combined with CO2 carbonation in repairing earthen city walls.

Compressibility of lime-treated dredged slurry with high water content

Lime is widely used for soft ground treatment, rendering the compressibility of lime-treated soil a crucial factor in deformation analysis in engineering applications. This study investigated the compressibility of three remoulded lime-treated slurries with high water content in Southeast China. Sixty groups of oedometer tests were conducted on lime-treated soils with an initial water content of 1 to 3 times the liquid limit and lime contents between 1 and 3%. The oedometer test results were discussed to examine the remoulded yield stress σy′\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\upsigma }_{y}^{\\prime}$$\\end{document} of lime-treated slurry. Considering the relationships between σy′\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\upsigma }_{y}^{\\prime}$$\\end{document}, the void ratio, lime content, and initial water content were preliminarily discussed and quantitatively established. Research on the normalised compression curve of lime-treated soil revealed that for soil samples containing a lime content of 0–%, the normalised compression curve at σp′\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\upsigma }_{p}^{\\prime}$$\\end{document}>σy′\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\upsigma }_{y}^{\\prime}$$\\end{document} can be represented by a unique line. Furthermore, the log(1 + e) − log σv′\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\sigma }_{\ ext{v}}^{\\prime}$$\\end{document} compression curve of lime-treated slurry at pre-yield state is analysed, and a prediction method for the modified compression index is proposed.

Multi-scale analysis of carbon mineralization in lime-treated soils considering soil mineralogy

Mineral carbonation is emerging as a reliable CO2 capture technology that can mitigate climate change. In lime-treated clayey soils, mineral carbonation occurs through the carbonation of free lime and cementitious products derived from pozzolanic reactions. The kinetics of the reactions in lime-treated clayey soils are variable and depend primarily on soil mineralogy. The present study demonstrates the role of soil mineralogy in CO2 capture and the subsequent changes caused by carbon mineralization in terms of the unconfined compressive strength (UCS) of lime-treated soils during their service life. Three clayey soils (kaolin, bentonite, and silty clay) with different mineralogical characteristics were treated with 4% lime content, and the samples were cured in a controlled environment for 7 d, 90 d, 180 d, and 365 d. After the specified curing periods, the samples were exposed to CO2 in a carbonation cell for 7 d. The non-carbonated samples purged with N2 gas were used as a benchmark to compare the mechanical, chemical-mineralogical, and microstructure changes caused by carbonation reactions. Experimental investigations indicated that exposure to CO2 resulted in an average increase of 10% in the UCS of lime-treated bentonite, whereas the strength of lime-treated kaolin and silty clay was reduced by an average of 35%. The chemical and microstructural analyses revealed that the precipitated carbonates effectively filled the macropores of the treated bentonite, compared to the inadequate cementation caused by pozzolanic reactions, resulting in strength enhancement. In contrast, strength loss in lime-treated kaolin and silty clay was attributed to the carbonation of cementitious phases and partly to the tensile stress induced by carbonate precipitation. In terms of carbon mineralization prospects, lime-treated kaolin exhibited maximum carbonation due to the higher availability of unreacted lime. The results suggest that, in addition to the increase in compressive strength, adequate calcium-bearing phases and macropores determine the efficiency of carbon mineralization in lime-treated clayey soils.

Mechanism of improvement and best-fit models for the prediction of geotechnical properties of lime stabilized expansive soil used in pavement subgrade

The performance of a pavement mainly depends on the quality of the subgrade layer. Expansive soils (ES) are extensively found worldwide including Pakistan. The inadequate strength and swelling behaviour of these soils are the main problems in any road construction project. Several researchers in the last decades have attempted to improve expansive soil utilizing various materials such as lime, brick kiln dust and fly ash. The purpose of this research was to evaluate the effect of lime on the engineering properties of the ES of a highway subgrade in the Sialkot region of Pakistan. The influence of different lime dosages (0%, 2%, 4% and 6%) at curing ages (1, 7, 14 and 28 days) has been examined by pH tests, plasticity tests, compaction tests, unconfined compressive strength (UCS), free swell index, and California Bearing Ratios (CBR). A field CBR and plate load test (PLT) on the natural soil and optimum lime-treated soil with various curing periods have been carried out for applicability as subgrade material. The test findings demonstrated that higher lime dosages increased the strength and ultimate bearing capacity (𝑞𝑢𝑙𝑡) of improved ES and at the same time decreased the free swelling index (FSI), optimum moisture content (OMC), maximum dry density (MDD) and permanent deformation of the subgrade soil. The UCS values of soil treated with 2%, 4% and 6% lime increased almost by 324%, 523%, and 249% for unsoaked samples and 285%, 351% and 231% for soaked samples respectively as compared to the plain soil at 28 days curing period. The laboratory CBR values significantly increased 2.35-8.50 times and field CBR improved 5.6 times as compared to the plain soil. The 𝑞𝑢𝑙𝑡 of lime-treated soil increased by 162% as compared to the plain soil and permanent deformation reduced from 33 mm to 2 mm after 28 days. Furthermore, equations were developed to estimate the best fit for the prediction of various geotechnical parameters and coefficient of determination (R2 ) values for all equations were found higher than 0.90. From the results, it has been concluded that adding the optimum lime content of 4% by weight satisfies the requirement for the subgrade construction of highways and the developed expressions can provide a scientific basis for estimating the geotechnical parameters.

Assessment of Engineering Behavior and Water Resistance of Stabilized Waste Soils Used as Subgrade Filling Materials

Urban construction has generated substantial amounts of waste soils, impeding urban ecological development. With the aim of promoting waste recycling, waste soils possess a high potential for sustainable utilization in subgrade construction. However, these waste materials exhibit inadequate engineering properties and necessitate stabilization for an investigation into their long-term performance as subgrade filling materials. Initially, a thorough assessment and comparison were conducted to examine the key mechanical properties of lime- and cement-stabilized soils with mixed ratios (total stabilizer contents ranging from 2% to 8%). The results indicated that these soils met the requirements of subgrade materials except for the 2% lime-treated soil. Subsequently, to reveal the improvement in water resistance of stabilized waste soil (e.g., under conditions of rainfall or elevated groundwater table), the effects of soil densities and stabilizer contents on the disintegration characteristics were investigated using a range of disintegration tests. An evolutionary model for the disintegration ratio of stabilized soils was then developed to predict the process of disintegration breakage. This model facilitates the quantification of the lower disintegration rates and elevated disintegration time attributed to higher levels of compactness and stabilizer contents during a three-stage disintegration process. This enhances the understanding and evaluation of sustainable applications in stabilized waste soils used as subgrade filling materials.

Prediction of unconfined compressive strength of lime treated soils

ABSTRACT Robust models based on Artificial Neural Network and simplified linear regression were proposed to predict the Unconfined Compressive Strength (UCS) of Lime Treated Soils (LTS). In total, an experimental database using 1120 test specimens was created. Critical examination of the collected experimental data suggested that there are eight key parameters that govern the attained strength gain. These input parameters are liquid limit, plastic limit, dry unit weight, water content, fine content, lime content, curing temperature and curing time whereas the only output dependent parameter is the UCS. The parameters of the proposed model including weights, biases and transfer functions were successfully converted to an explicit mathematical model relating the UCS with the key input parameters. Based on the results of the statistical evaluation, it was shown that a three-layered Artificial-Neural-Network model with 19 hidden neurons was capable to predict the UCS of (LTS) with a high degree of accuracy that was better than that achieved by the developed regression model. A coupling effect of the input parameters and weights analysis were conducted for the developed Artificial-Neural-Network-model to assess the importance of the key parameters. Analysis of weights of the model showed that curing time was the most significant factor affecting strength gain.

Response of Barley (Hordeum Vulgare L.) Genotypes to Soil Acidity, at Hula District, Sidama Region, Ethiopia

Barley (Hordeum vulgare L.) was domesticated at about 8000 B.C. It is one of the most important cereal crops in Ethiopia, accounting for over 60% of the food of the peoples living in the highlands of Ethiopia. Soil acidity is expanding in its scope, about 43 % out of the total cultivated land in Ethiopia, is dominated with acidic soil, as a sensitive highland crop, barley productivity is decreasing due to soil acidity and in areas where the problem is severe the crop is going out of production. A greenhouse pot experiment was conducted with the objective of performance comparison and screening of soil acidity-tolerant barley genotypes. The treatments consisted of two lime levels (with and without lime) and ten barley genotypes making up a total of 20 treatments laid out in a completely randomized design with six replications. Crop phenology, growth parameters, yield and yield components were evaluated. Primary root length, lateral root length, lateral root number, and root dry weight were significantly (P < 0.05) affected by the application of lime. Stand count at harvest, above-ground biomass, plant height, total seed number per pot, and seed number per plant were significantly (P < 0.05) affected by the application of lime. Accession 215454a, has shown a greater value of relative root length measurement with 73.76 centimeter. The study revealed the impact of soil acidity could be so severe it can result to the extent of having no yield as compared to lime-treated soils. This necessitates the use of lime in areas that are prone to acidic soils. Overall, the accession that showed relative tolerance from early stage screening can be candidate for further breeding program to develop barley variety that is tolerant to acidic soils.

Profitability analysis of bread wheat technology demonstration on lime-treated soils using a cluster approach in selected areas of the east Gojjam zone, northwestern Ethiopia

Access to improved varieties and soil acidity problems are the growing and significant hindering factors for the production and productivity of wheat in Ethiopia. The activity was conducted to enhance farmers’ awareness, knowledge and skills on wheat production under lime treated soilsand improve the household’s income and accessibility forimproved technologies in the study areas. Aneded, Awabel, Basoliben, Debre Elias and Gozamin districts were selected purposively based on wheat production potential and the prevalence of soil acidity. Both quantitative and qualitative data were collected using appropriate data collection tools. A total of 712 smallholder farmers participated and 10 wheat clusters were formed. The data were collected from the cluster farming participants the smallholder farmers. Simple descriptive and inferential analysis methodsweredeployed. The study revealed that producing wheat under lime treated soils through a cluster approach has a significant yield advantage over the traditional production system. Additionally, the profitability analysis resultsrevealed that the marginal rate of return and marginal net benefitfrom wheatproductionunder lime treated soilsweresignificantly high overthree consecutive years. Therefore, the demonstration of improved wheat variety under lime treated soils usingcluster approach should be encouraged and scaled up toreachmore smallholder farmers in unaddressed areas with similarclimatic condition across the country to boost production and productivity, increase household income and reduce food insecurity amongsmallholder farmers.

Mechanical Properties and Microscopic Mechanism of Basic Oxygen Furnace (BOF) Slag-Treated Clay Subgrades

Civil engineering faces a substantial challenge when dealing with soft and compressible clayey soils. Conventional soil stabilization techniques involving ordinary Portland cement (OPC) result in notable CO2 emissions. This study explores the utilization of basic oxygen furnace (BOF) slag, a by-product of steel production, for strengthening kaolin clay. This research investigates the influence of BOF slag particle size, BOF slag content, and the use of activators such as lime and ground granulated blast-furnace slag (GGBFS) on the stabilization of kaolin clay. The strength development is assessed through unconfined compressive strength (UCS) test, bender element (BE) test, and scanning electron microscopy (SEM). The findings reveal that higher BOF content and extended curing periods enhance soil strength, and lime and GGBFS effectively augment the stabilizing properties of BOF slag. Stabilizing kaolin clay with a 30% BOF/GGBFS mixture in a 50/50 ratio with 1% lime and curing for 7 days yielded a compressive strength of 753 kPa, meeting the Federal Highway Administration’s requirement for lime-treated soil. These combined measures contribute to developing a more robust and stable material with enhanced geotechnical properties.

Soil surface-atmosphere interaction in a monitored embankment constructed with two compacted lime-treated soils

This study was carried out in an instrumented and monitored embankment divided into two symetrical sections and constructed with compacted treated soils (i.e., a silty soil and a clayey soil) exposed to the same atmospheric conditions in a continental climate, with oceanic influences. It aimed to investigate changes of bare soil surface moisture (w) and corresponding suction (s) as result of soil water evaporation processes on a monthly time scale. Seasonal variations in the w (and s) measurement in both soil surfaces show overall consistency with the meteorological measurement within the study area. The paper also examines the ability of four air temperature-based potential evaporation (PET) formulations to capture the process of evaporation at the site. Results indicated that soil water evaporation is controlled by both atmospheric and soil conditions. And, during the most significant drying time period, the measured s consistently increased and the corresponding w decreased suggesting a relatively significant water evaporation effect. However, the monthly predicted PET data varied from a maximum of over 120 mm/month to less than 50 mm/month during the drying time, depending on the used method. The continuously monitored soil surface suctions are used for discussing the variations of evaporation according to the predicted PET method and time period at the site.

Triaxial tension and compression tests on saturated lime-treated plastic clay upon consolidated undrained conditions

Lime-treatment of clayey soil significantly increases its shear and tensile strengths. Consequently, the tensile strength of lime-treated soils deserves careful investigation because it may provide an appreciable benefit for the stability of earth structures. This study investigates the tensile and shear strengths of an untreated and lime-treated (3% of lime) plastic clay at different curing times (7 d, 56 d and 300 d), through triaxial tension and compression tests. Triaxial tension tests are performed using “diabolo-shaped” soil samples with reduced central section, such that the central part of the specimen can be under axial tension while both end-sections remain in axial compression. Consolidated undrained (CU) conditions with measurement of pore water pressure allow analyzing the failure conditions through effective stress and total stress approaches. The results of triaxial tension tests reveal that the failure occurs under tensile mode at low confining pressure while extensional shear failure mode is observed under higher confining pressure. Consequently, a classical Mohr-Coulomb shear failure criterion must be combined with a cut-off tensile strength criterion that is not affected by the confining pressure. When comparing shear failure under compression and tension, a slight anisotropy is observed.

Investigating Effect of Soluble Sodium Sulphate Contamination on Swell Behaviour of Untreated and Lime-Treated Soil

Investigating Effect of Soluble Sodium Sulphate Contamination on Swell Behaviour of Untreated and Lime-Treated Soil

Erosion Mitigation Using Grass, Riprap, Lime, and Enzymes

This paper presents the results of research on soil erosion and its mitigation by different methods such as grass, riprap, lime, and enzymes. The goal was to evaluate these methods for their degree of efficacy using laboratory erosion testing. The paper begins with a review of existing knowledge on erosion mitigation methods. The erosion resistance of natural and improved soil was investigated in the erosion function apparatus (EFA), a laboratory device for measuring erosion resistance in the velocity range of 0.3 to 6.5 m/s. EFA testing was performed on grass-covered soils, riprap-covered soils, enzyme-treated soils, and lime-treated soils. The erodibility of the soils before and after treatment was compared. The results of the EFA tests were also compared with a few large-scale field tests available in the published literature. The advantages, limitations, and range of applications of each erosion mitigation method are provided.

Physicochemical and Strength Behavior in Lime-Treated Soil Submerged under Gypsum and Sodium Sulfate Contamination

Physicochemical and Strength Behavior in Lime-Treated Soil Submerged under Gypsum and Sodium Sulfate Contamination

Effects of sticky rice on the carbonation reaction of lime-treated soil in earthen sites

Earthen sites with important historical, artistic, social, cultural, and scientific values have suffered serious damage due to long-term influences from various natural factors. The sticky rice and lime composite shows the potential to be applied to the protection of earthen sites. The carbonation of lime has a significant impact on the engineering properties of earthen sites. The main purpose of this study is to investigate the effect of sticky rice on the carbonation reaction of lime-treated soil in earthen sites. The results indicated that sticky rice can inhibit the carbonation reaction of lime, resulting in a reduced calcium carbonate content. The inhibition effect of sticky rice on carbonation reaction of lime could be attributed to the limitation of gaseous water and CO2 gas diffusion. Sticky rice had both binding effect and inhibition effect on lime-treated soil, and its mechanical properties depended on the dominant effect after these effects cancelled each other. When the lime content was ≤6%, the addition of sticky rice can increase the strength of soil. When the lime content was >6%, however, the addition of sticky rice resulted in a decrease in strength. In addition, the carbonation of the outside of the cylindrical sample was higher than that of the inside. These findings can increase the understanding of protecting earthen sites with sticky rice and lime composite, and optimize the application of sticky rice and lime composite.

Impact of silicate and lime application on soil fertility and temporal changes in soil properties and carbon stocks in a temperate ecosystem

Most agricultural soils are unproductive due to soil acidity which limits crop growth and yield. To ameliorate soil acidity constraints and enhance the ecosystem services the soil renders to achieve optimum crop yields, lime, and silicate are mostly used. However, there are few studies reporting the impacts of the combined application of silicate and lime on soil properties, soil fertility and carbon stocks and stratification in long-term experiments. This study evaluated the impacts of the combined application of silicate and lime on soil fertility indicators (pH, soil organic matter (SOM), available phosphorus, exchangeable potassium, magnesium, and calcium, and available SiO2), carbon stratification and stocks in comparison to sole lime and sole silicate applied to a Fluvaquentic Eutrudepts over a 67-year period. Each treatment’s rate of application was calculated to raise the soil pH to 6.5. Incorporation of the treatments increased the soil pH by 1.30, 1.22, and 1.35 folds in the sole silicate, sole lime, and combined silicate and lime-treated soils, respectively, relative to the baseline soil pH (5.5). The combined application of silicate and lime resulted in significant decreases in C stratification and C stocks. The significant reduction in the C stocks in the silicate and lime-treated soils implies that its long-term application could potentially reduce carbon sequestration and increase the carbon footprint of rice cultivation. This information is crucial to develop sustainable soil management interventions to curtail the environmental footprint in rice paddy ecosystems. Comparatively, the combined silicate and lime treatment caused an increase in the relative change of soil fertility by 65.7% and the average annual growth rate in the soil fertility improvement by 0.0115, as compared to the untreated soil. Among the soil variables, soil pH, exchangeable calcium, and available silicate contributed most to the variation the soil fertility. The obtained results could serve as a guide in revising the lime and silicate fertilization programs instituted by the Korean Government and reviewing national soil fertility management systems in temperate paddy ecosystems.

Physicochemical and Microstructural Evaluation in Lime-Treated Silty Soil Exposed to Successive Wetting-Drying Cycles Submitted to Different Testing Conditions

Physicochemical and microstructural evolution in lime-treated soil subjected to successive wetting and drying (W-D) cycles was investigated, and the relevance of the laboratory-implemented testing condition with in situ conditions was discussed. Lime-treated soils were exposed to 17 W-D cycles using different testing conditions. Two laboratory testing conditions were operated at laboratory temperature, consisting of W-D duration representing the saturation level close to the one experienced in the in situ soil during rainy and drought periods. The results obtained were interpreted in terms of those obtained using a reference procedure from current standards, which involved oven-drying specimens at 71°C. Drying of lime-treated soil at 71°C reduced the water content from about 20% to 0.85%. This has led to greater contact between soil particles, thus increasing the suction from about 143.5 to 270 MPa. Such a phenomenon increased the unconfined compressive strength (UCS) of the oven-dried soil up to about three times compared with the air-dried specimen, although the available cementitious bonding, reflected by the presence of pores smaller than 3,000 Å, was comparatively low in the former compared with the latter. Percentage leaching of calcium components with respect to the initial calcium content of the soil was significantly low during W-D cycles due to greater exposure of only the outer part of the compacted soil structure during wetting. However, the leaching was comparatively higher in the oven-dried soil. The implemented wetting duration and drying temperature influenced the wetting front velocity of water, which significantly affects the duration taken by infiltered water to invade the core of an earthen structure, and hence its durability.

COMPACTION CHARACTERISTICS OF SOFT SOIL STABILIZED WITH LIME AND METAKAOLIN-BASED GEOPOLYMER

Aim: This study was conducted to investigate the effect of lime and metakaolin-based geopolymer on soft soil's compaction characteristics. Method: The compaction was done using an automatic soil compactor according to the ASTM-D698 testing procedure. The geopolymer synthesis was prepared in the ratio of 5%,10% and 15% of the dry weight of the soil using sodium hydroxide and sodium silicate alkali activators. In addition, lime was added in amounts of 6% of the soil's dry weight. Findings: It was discovered that soft soil had an optimum moisture content (OMC) of 26% and a maximum dry density (MDD) of 1.52 g/cm3.However, lime-treated soil has a maximum dry density of 1.47 g/cm3 and an optimum moisture content of 27%. The maximum dry density of the 15% geopolymer-treated soft soil was higher than the soft soil, which was approximately 1.53g/cm3. Conclusion: A reduced maximum dry density and higher optimum moisture content were observed in the soil treated with a lime and geopolymer mixture. The metakaolin-based geopolymer treatment increased the maximum dry density and decreased the optimum moisture content.

Investigation of the strength evolution of lime-treated London clay soil

The paper investigates the effect of hydrated lime on shear strength properties and behaviour of London clay, triaxial. Unconsolidated undrained tests were performed to identify the effect of lime dosage, compaction water content and curing time on the shear strength and stress–strain behaviour of the treated soil. The mineralogical and physicochemical transformations occurring during the curing of the soil were also monitored. The results showed that strength gain was strongly influenced by lime content and the curing period, whereas compaction water content was less influential. It was found that the strength evolution is likely to continue over long periods of time and result in very considerable strength gains on the hardening of pozzolanic reaction products. It was also shown that adequate early strength gains can be obtained with reduced material consumption, thus further increasing the sustainability of the treatment processes. The paper also highlighted the importance for engineering design of considering the brittle stress–strain response of the lime-treated soil, and the benefit of using lower amounts of lime to alleviate this undesirable effect. The implications of various aspects of soil brittleness in different situations merit further attention and should be explored by way of modelling in future work.