Comparative Performance of Cement and Lime with Costus bracteatus Rowlee on Stabilized Soil

Abstract The study investigated the comparative performance of cement and lime admixtures blended with varying dosages of bagasse ash from Costus bracteatus Rowlee for stabilization of problematic expansive black cotton soil. Laboratory characterization tests were conducted to assess the impact on compaction, shear strength and compressibility characteristics. Results showed that both CB and LB composite mixtures improved the engineering properties of the soil. However, a comparative evaluation was also presented. At 12% bagasse ash, the MDD of CB mixes at 1554kg/m3 exceeded LB mixes by 7.1% due to cement hydration reactions. The OMC of CB mixes at 13.12% was 4.2% lower than LB mixes attributable to cement's lower water demand. At 10% ash, LL and PI of LB mixes exceeded CB mixes by 2.1% and 0.9% respectively due to lime’s stronger plasticizing impact. However, the PL difference was marginal at 0.5% higher for LB mixes. Unsoaked and soaked CBR values progressively improved, with CB mixes surpassing LB mixes by 1.4% and 1.2% attributable to cement's pore optimization. The UCS amplified up to 10% ash dosage due to bagasse ash's pozzolanic reactions. Nevertheless, at 10% ash CB mixes achieved a UCS of 212.1MPa, surmounting LB mixes by 6.8% attributable to cement matrix’s superior strength attributes. In conclusion, both composite mixtures improved expansive soil properties suitably for construction applications. However, cement additive consistently outperformed lime by 1–7% for strength parameters owing to its pore-optimizing pozzolanic reactions, establishing its technical advantages. Bagasse ash proved effective in augmenting treated soil performance when blended with either binder.