Optimization of construction and demolition waste-based compressed stabilized earth blocks using Taguchi–MCDM: A circular economy approach to sustainable construction

The reuse of construction and demolition (C&D) waste in earth-based construction materials offers significant potential to reduce resource depletion and landfill burden; however, existing studies largely treat C&D waste as a secondary replacement material and lack systematic mix optimization and decision-based validation. To address this gap, the present study develops Modified Compressed Stabilized Earth Blocks (M-CSEBs) by treating recycled fine aggregate (RFA) derived from C&D waste as a primary mix design variable within a circular economy oriented framework using Taguchi method. The optimized mixes were evaluated for mechanical, durability, and thermal properties. Microstructural characterization using SEM, FTIR, and XRD was conducted to explain performance. Multi-Criteria Decision Analysis (MCDA) was applied to rank the mixes based on compressive strength, water absorption, and thermal conductivity. The optimal mix (F3), containing 75% C&D waste and 25% soil, achieved a compressive strength of 7.96 N/mm², water absorption of 6%, and thermal conductivity of 0.626 W/mK. The findings demonstrate that performance-driven optimization and decision-based evaluation enable the effective use of C&D waste in durable and thermally efficient earth blocks, supporting circular material use and sustainable construction.