Sustainable stabilization of high plasticity clay using construction and industrial wastes

Abstract This research examines the impact of additives (wastes-derived additives) on volume change behavior (swelling, consolidation) and strength of a highly plastic expansive clay. The experimental pro-gram aimed to evaluate the potential of three waste-based stabilizers; recycled concrete aggregate powder (RCA), crushed red brick (CRB), and fly ash (FA) to improve the hydro-mechanical performance of expansive clays while promoting sustainable waste reuse. Each material was incorporated into the expansive clay at six proportions (0%, 2%, 4%, 8%, 14%, and 25%) by dry weight of the clay. Comprehensive laboratory testing, including swell and compressibility tests as well as the unconfined compression test (UCS, at two curing times; 1 and 14 days), was conducted to evaluate alterations in the hydro-mechanical performance of expansive clay focusing on its swelling properties, compressibility indexes, and strength development. The results demonstrated that the inclusion of additives led to a significant reduction in swell potential and compressibility, accompanied by a considerable increase in unconfined compressive strength. Among the tested additives, FA and RCA exhibited the most effective overall performance, attributed to their cementitious components and coarse particle structure, which contributed to improved particle interlocking and pozzolanic activity, particularly at higher dosages, whereas CRB yielded minimal improvements that decayed at higher contents or extended curing intervals. SEM technique was utilized to view the microfabric structure of selected samples. The research contributes to advancing sustainable ground improvement practices by reducing dependence on conventional additives and minimizing the environmental impact of construction waste.