Evaluation of lateritic soil stabilized with lime and periwinkle shell ash (PSA) admixture bound for sustainable road materials

The indiscriminate disposal of periwinkle shells as agricultural waste at landfills has saddled geo-environmental engineers with the responsibilities of reutilizing these wastes as construction materials for dual purpose of soil stabilization and effective waste disposal. In this research, lime and periwinkle shell ash (PSA) under laboratory conditions were effectively utilized in stabilizing lateritic soil so as to validate its potentials for use as pavement layer materials. Lateritic soil treated with lime at 0-8% and PSA at 0-10% (each at 2% increments) by dry weight of soil was evaluated for index properties, maximum dry density (MDD), optimum moisture content (OMC), California bearing ratio (CBRS and CBRU) and unconfined compressive strength (UCS) using the standard Proctor test. The scanning electron microscope (SEM) and Fourier transformation infrared (FTIR) were also used to determine the morphological changes and functional groups in the stabilized soil. There was a general decrease in consistency limits as the stabilizers increased. Furthermore, MDD decreased with increase in OMC. For the UCS test, peak strength of 895, 1810 and 2670.45 kN/m(3) (at 7, 14, and 28 days), respectively, occurred at 8% lime/ 8% PSA. The untreated soil with CBRS and CBRU of 4.3 and 11.5% peaked at 79.3 and 91.2% (8% lime/8% PSA), respectively. SEM resulted in the formation of new microstructural arrangements, while FTIR displayed distinctive functional groups as regards their specific bands for the natural and stabilized soil. The study concluded that the inclusion of lime and PSA could be of economic benefits in improving marginal soils.