Stabilisation of soft soil with recycled plaster admixtures

Abstract

Solid waste management is a serious problem worldwide as the amounts of produced wastes are increasing annually. For example, the disposal of waste gypsum plasterboard, used as dry walling across the world, represents a serious environmental issue. Therefore, this study examines the potential for reusing plasterboard wastes as a stabiliser material for earthwork projects, especially for organic soft clay soil. Recycled plaster, mixed with cement or lime at different ratios was used as a stabiliser for tested soil. Atterberg limits, scanning electron microscopy, x-ray diffraction, compressive strength, and secant moduli tests were conducted to evaluate the improvement in stabilised soil properties. The results indicate that the inclusion of plaster–cement (B–C) or plaster–lime (B–L) admixtures improved the geomechanical properties of the stabilised soil, with higher admixture concentrations leading to greater improvement. Moreover, the soil specimens stabilised using the B–L admixture exhibited a higher strength gain rate and reduction in plasticity index and water content than those stabilised by the B–C admixture. The development of cementation compounds in a stabilised soil matrix has a considerable effect on permanent strength enhancement. It is concluded that the proposed stabilising technique can be valuable for both waste management and construction industries.