Performance of Geopolymer and Cement Stabilized Black Cotton Soil as Road Materials

Abstract

Portland cement and hydrated lime are conventional stabilizers used to mitigate the volumetric instability and high plasticity of black cotton soil (BCS). However, increasing concerns over the environmental impacts of these stabilizers have motivated researchers to explore alternative, more sustainable, and non-conventional stabilizers. In this study, BCS was stabilized with slagbased geopolymer and compared with cement-stabilized soil for potential application as a sustainable road material. The BCS was treated with different proportions of geopolymer (5%, 10%, and 20%) and cement (4%, 12%, and 15%) by dry weight. Laboratory investigation was carried out to determine the changes in the plasticity behavior and compaction characteristics of soil-additive mixes, as well as the UCS of stabilized soil. Test results show a reduction in the plasticity behavior and improvements in the maximum dry density and strength of BCS with the addition of stabilizers. The 28-day strengths of 5.1 MPa and 4.25 MPa were achieved with 20% geopolymer and 15% cement contents, respectively. The efficacy of stabilized soil as basecourse substitute in rural roads was evaluated using a mathematical model of a two-layer flexible pavement system, and deformations were calculated under a standard axial dual-wheel load. The results showed that the geopolymer-stabilized base course material has lower deformations than the cement-stabilized and conventional granular base course materials.