Compaction Behaviour of Lateritic Soil–Calcium Chloride Mixtures

Abstract

Laboratory studies on lateritic soil treated with up to 8% calcium chloride (CaCl2) by dry weight of soil was carried out to establish the soil improving potential. Tests carried out include Atterberg limits and linear shrinkage, compaction characteristics (maximum dry density, MDD and optimum moisture content, OMC), strength characteristics (unconfined compressive strength, UCS and California bearing ratio, CBR) and microanalysis. Compaction and strength characteristics test were investigated using three compactive efforts [i.e. British Standard light, BSL (standard Proctor), West African Standard, WAS or ‘intermediate’ and British Standard heavy, BSH (modified Proctor)]. Results obtained show that Atterberg limits decreased with increased calcium chloride content. MDD increased with a corresponding decreased OMC of the soil–CaCl2 mixtures for the three compactive efforts. Peak UCS and CBR values were obtained at 4% CaCl2 content with increasing compactive effort. Microanalysis using Scan Electron Microscope, SEM shows the transformation of surface morphology at the edges of clay particles. Statistical analysis of result shows that CaCl2 content had significant influence on the Atterberg limit parameters and both the variations of CaCl2 content and compactive effort had significant effect on the strength parameters, maximum dry density as well as the optimum moisture content. The R2 values of regression models show that CaCl2, LL, MDD, OMC and CE have considerable influence on the UCS at 7 days curing and CBR values. Peak strength values are below those recommended for sub base and base stabilization, hence CaCl2 is not convenient as a stand-alone stabilizer but can be adequate as a modifier or as admixture in Cement or lime stabilization of lateritic soil.