Effects of Lime Addition on the Plasticity of Tropical Clay Soils with Different Mineralogical Composition

Abstract

The influence of hydrated lime on the plasticity of six tropical soils from Sudan having different mineralogical composition and constituents has been studied. The mineral constituents of the clay fraction of these soils vary from predominantly montmorillonitic, predominantly kaolinitic to mixed minerals. Lime has been added in varying percentages by weight and Atterberg limits have been determined for the untreated and lime treated soils. The test results have shown that on treatment with lime the Liquid Limit (LL) has decreased, the Plastic Limit (PL) has increased and the Plasticity Index (PI) has subsequently decreased for all the soils. The Optimum Lime Content (OLC), the Initial Consumption of Lime (ICL) and the Lime Fixation Point (LFP) have been defined and determined. A very good relationship between ICL and the Activity of the untreated soils (Ae) has been found out. The drop in PI and LL upon treatment with OLC is directly proportional to PI and LL, respectively. Montmorillonitic clay soils react faster with lime compared to kaolinitic clays. The OLC is higher for montmorillonitic clays compared to kaolinitic clays.