Experimental Study on Post-Earthquake Recycled Concrete Aggregates in Concrete Mixes for Sustainable Structural Application

An earthquake and its impact become a significant challenge for the Himalayan region. Earthquakes result in widespread structural damage, generating enormous construction and demolition waste, particularly concrete debris. Recycled Concrete Aggregates (RCA), obtained by processing demolished concrete structures, offer a viable solution to resource depletion and waste management. This study investigates the fresh and hardened properties of concrete incorporating varying proportions (0%, 25%, 50%, 75% and 100%) of RCA as a replacement for natural coarse aggregates. Standard concrete tests were conducted at different curing periods including slump, compressive strength, split tensile strength, water absorption and density. The results indicate a workability and mechanical performance decline with increasing RCA content due to higher porosity and weaker interfacial transition zones. Nevertheless, mixes with up to 50% RCA showed acceptable strength and durability parameters. The study also highlights the significant influence of RCA on water absorption and modulus of elasticity, emphasizing the need for mix optimization and surface treatment. Overall, using RCA in concrete is technically feasible and environmentally beneficial, contributing to sustainable construction practices. Fresh Concrete remains superior for primary load-bearing and seismic-resistant structures, with up to 30% better performance under earthquake loading. RCA Concrete, especially with ≤ 50% replacement, can be effectively utilized in non-structural or secondary structural elements, offering a 20-40% environmental benefit through waste reduction and reuse. In post-earthquake reconstruction scenarios, RCA concrete provides a cost-effective, sustainable and locally available alternative, reducing material costs and debris waste by up to 50-60%, providing proper mix design and ensuring quality control.