Soft cohesive clays are normally associated with large settlements and low shear strength. Various techniques are available to reduce the problems. One of the low cost techniques is to modify the soil with lime in-situ to make it workable for construction and allow it to increase in strength by pozzolanic reactions between lime and clay mineral. To implement this technique, physical, geochemistry and mineralogy investigation were performed to evaluate the lime stabilisation potential for several Malaysian soils. The physical, geochemistry and mineralogy characteristics of lime-soils admixtures have shown a significant potential in improving the geotechnical properties of Malaysia cohesive soils. Lime fixation capacity (LFC) and initial consumption of lime test (ICL) were performed to compare and establish mix design for lime modification. Unconfined compressive strength test (UCS) was conducted to determine the comparison between the stabilised and unstabilised soil in term of soaked and unsoaked strength. X-ray diffraction (XRD) and X-ray florescence (XRF) analysis were used to identify the clay minerals and geochemistry composition and their correlation to strength development. Typically, there is an increase in plastic limit due to addition of lime, which make the soil more workable. Lime content between 3% to 6% has contributed to the increase in unconfined compressive strength from 2.5 to 10.5 times of the untreated soils. Maximum dry density however reduces with addition of lime but the optimum moisture content increases due to the higher consumption of water for treated soil. Higher Al2O3/SiO2 ratio of a soil also corresponds to higher UCS of the lime-treated soils. This is a new indicator to determine the potential of strength development in lime-stabilised soil. The value of loss on ignition (LOI) of untreated soil is another useful indicator for predicting the UCS gain. The presence of calcium aluminate silicate hydrate (CASH) from XRD result at 14 days indicates the early formation of new product due to lime soil reaction. Crystallisation of CASH can be observed from the development of calcium aluminate hydrate (CAH) and calcium silicate hydrate (CSH) identified from XRD analysis and their morphology from scanning electron micrographs (SEM). The strength development of lime-stabilised soil is governed not only by the clay fraction (CF), plasticity and pH of the soil as specified in BS and ASTM but also influenced by the geochemistry and mineralogy aspect of the soil.
KOK KAI CHERN; Faculty of Civil Engineering
KOK KAI CHERN; Faculty of Civil Engineering
