Department of Civil Engineering

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Subject: search.filters.subject.Lime treatment

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    Lime stabilization of sulfate-rich soil using quarry fines as a sustainable co-admixture
    (Springer, 2025-05) Chakraborty, Sayantan
    The engineering properties of the underlying soil govern the durability and performance of civil engineering infrastructures. Chemical stabilization using lime is adopted widely to treat problematic clayey soils that do not possess acceptable engineering properties. However, the presence of sulfate salts is often counterproductive due to ettringite formation. Precompaction mellowing or the addition of amorphous silica-rich co-admixtures like fly ash or ground granulated blast furnace slag are widely used to mitigate ettringite-induced heaving. This research study investigates the potential of utilizing a crystalline silica-rich sustainable co-admixture derived from quarry dust to improve the engineering properties of sulfate-rich soil with kaolinite as the predominant clay mineral. Unconfined compressive strength tests, with and without capillary soaking, and one-dimensional (1D) free swell tests were performed on specimens treated with lime alone and lime along with quarry fines after different curing periods to assess the extent of strength reduction and swelling characteristics after moisture exposure. Mineralogical and microstructural analyses using X-ray diffraction and scanning electron microscope imaging with energy-dispersive X-ray spectroscopy were used to investigate the potential causes of the observed changes in strength and volume change characteristics. Results indicate that lime, along with quarry fines, effectively stabilized the problematic sulfate-rich soil. The improvement in engineering properties was prominent at higher dosages of quarry fines and after prolonged curing time.
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    Micro-mechanical analyses to understand the durability of chemically stabilized geomaterials against moisture-induced damage
    (ASCE, 2025) Chakraborty, Sayantan
    Chemical stabilization with calcium or Ca-based stabilizers, such as lime, has been used worldwide to enhance the engineering properties of problematic soils. Although lime treatment improves the mechanical properties of problematic soils, moisture intrusion is often detrimental to the stabilized layers. The extent of improvement and the durability of the lime-treated soils depend on several factors, including stabilizer dosage, curing period, and soil type. This research study was designed to investigate the influence of predominant clay minerals and stabilizer dosage on the durability and resiliency of lime-treated soils against moisture-induced damage. Two clayey sand groups bearing kaolinite and montmorillonite as the predominant clay minerals were treated with the Ca-based stabilizer as per existing recommended practice, and the strength and durability properties were studied after different curing periods. Besides engineering tests, mineralogical and microstructural analyses were also considered to identify the reasons responsible for the observed engineering behavior before and after moisture conditioning. Test results indicate that the extent of strength gained after lime treatment is less for soils with kaolinite as the predominant clay mineral than those containing montmorillonite. However, the percentage strength loss after capillary soaking was lower in lime-treated kaolinite-rich soils compared to that having montmorillonite when treated with optimum +2% lime dosage and cured for a longer time.
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    A Novel Method to Improve the Durability of Lime-Treated Expansive Soil
    (Springer, 2021-04) Chakraborty, Sayantan
    Pavements often suffer from different distresses such as rutting and cracking due to the presence of underlying expansive subgrade soils. The ingress and egress of water have a detrimental effect on the performance of the pavements due to the swell-shrinkage behaviour of the subgrade soil. Millions of dollars are invested annually for the maintenance and rehabilitation of such pavements. Traditionally, lime has been used for treating problematic subgrade soils to enhance the strength, stiffness and other engineering properties. However, previous studies have shown that lime-treated soils often incur a significant strength loss when exposed to moisture intrusion, especially in the early curing periods. This research work explores the possibility of using a novel silica-based admixture to enhance the engineering properties of lime-treated soil, reduce the swelling potential and deter the moisture-induced strength loss incurred during early curing periods. Laboratory test results suggest that an expansive soil treated with lime and silica-based admixture has a significant reduction in water absorbing potential and strength loss during the early stages of curing as compared to the soil treated with lime only.