Permanent deformation behaviour of black cotton soil treated with calcium carbide residue

Abstract

Uncontrolled dumping of huge quantities of calcium carbide residue (CCR) which is an industrial by product of acetylene gas industry is hazardous to environment due to its high alkalinity. Utilization of calcium carbide residue for stabilization of subgrade soils is a cost effective and sustainable practice, which can be adopted in design and construction of flexible pavements. In the present work, the efficacy of treatment with CCR in reducing the accumulation of permanent deformations in black cotton soil (BC soil) subgrade subjected to repeated loading is investigated. Untreated black cotton soil samples and CCR stabilized samples are subjected to repeated load triaxial tests for determining the accumulation of plastic strain with repeated loading cycles. Effect of cyclic deviatoric stress levels and moulding water content on the development of permanent deformation is examined. The accumulation of permanent deformation is quantified using the critical cyclic stress levels based on the shake down theory. The experimental data for the permanent deformation of treated as well as untreated soil samples is found to fit well with two the models (VTT model and power law model) reported in literature. The efficacy of CCR stabilization in reducing the permanent deformations of black cotton soil subjected to repeated loading is confirmed based on the mineralogical and morphological studies carried out on the treated samples.