Enhancing Concrete Sustainability: Synergistic Effects of Individual and Dual Treatments on Recycled Coarse Aggregate from Construction and Demolition Waste

This research investigates the impact of various treatment methods on recycled coarse aggregate (RCA) derived from construction and demolition waste (CDW) to enhance the sustainability of concrete. Four treatment methods were employed: [A] HCl (1M), [B] Na2SiO3 solution (45%), [C] Bacillus sphaericus bacteria solution, and [D] carbonation chamber. Initially, RCA batches were treated separately, followed by combination treatments involving the carbonation chamber and CO2 exposure. To assess efficacy, weight change tests and physical properties were measured, comparing treated and untreated RCA. The treated RCA was then used to cast M30 concrete, and its mechanical properties were evaluated through tests for compressive strength, split tensile strength, drying shrinkage, and ultrasonic pulse velocity. The different tests test included sets of untreated RCA, individually treated RCA, and combined-treated RCA. The results indicated that the combination treatment using Bacillus sphaericus bacteria and the carbonation chamber produced the most optimal outcomes. This treatment significantly improved the physical and mechanical properties of the concrete, demonstrating its potential for enhancing the performance of RCA. These findings are crucial for promoting sustainable waste management and reducing the environmental impact of the construction industry by facilitating the effective reuse of CDW in concrete production.