Effectiveness of Bagasse Ash Incorporating Limestone Calcined Clay Cement in Improving Shear Strength and Durability Properties of Black Cotton Soils

This study aims to investigate the capacity of bagasse ash (BA) incorporating limestone calcined clay cement (LC3) for stabilisation of black cotton soil (BCS) in Shire Valley, Malawi, in terms of shearing and durability properties. First, BA and LC3 were developed, and their physiochemical properties were investigated. Specimens were created of BA incorporating LC3 in mix ratio of 2:1, respectively. BA incorporating LC3 specimens were blended into BCS at mix proportions of 0% to 12%. The mixtures were subjected to 3, 7, 15 and 30 curing days, and 10°C and 32°C curing temperatures, under confining pressures of 150, 300 and 450kPa for direct shear test. Effect of simulated whether condition of wetting–drying cycles (WDCs) on behaviour of treated BCS was investigated through durability test. The results showed that the shear strength of 12% treated BCS increased above 70% on average, with higher values at 450kPa confining pressure, and that the shear strength of treated BCS cured at 10°C was lower than that cured at 32°C. Durability test results illustrated that the 4% treated BCS collapsed upon immersing in water. The 8% treated BCS reduced against WDC. The 10% and 12% treated BCS specimens displayed an increasing trend against WDC, indicating both short- and long-term hydration stabilisation reaction. This study shows the feasibility of BA incorporating LC3 for BCS stabilisation relevant to geotechnical construction in tropical climatic regions and further promotes the reuse of by-products and wastes as cementitious materials for BCS stabilisation practice.