Mechanical Properties of Black-Cotton Soil Stabilized with Recycled Concrete Dust

Abstract

Black-cotton soils (BCS) impose significant challenges in geotechnical and pavement engineering due to their tendency to undergo large volumetric changes, leading to structural failures of subgrade layer. Stabilization is essential to improve their mechanical properties of these soils, but traditional stabilizers such as cement and lime contribute to higher carbon emissions. Hence, this study aimed for the use of recycled concrete dust (RCD), a waste by-product of concrete demolition, as a sustainable alternative for soil stabilization. The primary objective is to evaluate the effectiveness of RCD in enhancing the mechanical properties of BCSs, including compaction characteristics, unconfined compressive strength (UCS), California bearing ratio (CBR) and shear properties. In the present study, two-types of black cotton soils (low and high-compressible clay soils) were collected and stabilized with RCD2 (with maximum size of 2.36 mm) and RCD3 (with maximum size of 4.75 mm) at a dosage of 0, 5, 10, 15, 20 and 25% by weight of soil. Further, the study evaluated the influence of potable water and bore-well water on the mechanical properties of these soils. The experimental outcomes from the CBR, UCS, and triaxial tests reveal that increasing amounts of recycled concrete dust (RCD2 and RCD3) notably improved the load-bearing capacity, unconfined compressive strength, and shear strength of both CH (highly compressible) and CL (low compressibility) soils. Using potable water generally provided superior results compared to bore-well water, indicating that water quality plays a role in further optimizing the stabilization process. These results underscore the potential of recycled concrete dust as an effective soil stabilizer, supporting the development of sustainable and robust infrastructure solutions for expansive and weak soils.