Carbon-Efficient Concrete Mixes using Recycled and Secondary Aggregates with LCA Insights

Abstract

Incorporating recycled materials into concrete presents a viable strategy for enhancing sustainability in construction. Ceramic tile waste (CTW), a hard-to-dispose by-product from construction activity, represents a critical environmental concern due to its non-biodegradable nature and landfill burden. This work evaluates M30 grade concrete prepared with 30% Recycled Coarse Aggregate (RCA) and 30% Ceramic Tile Waste (CTW) as partial replacements for natural coarse aggregate. Three concrete mixes—control, RCA-30%, and CTW-30%—were evaluated through mechanical tests, selective durability tests (only for RCA), and environmental assessment using Life Cycle Analysis (LCA) across real-time construction case studies. Mechanical testing showed that RCA concrete achieved a 28-day compressive strength of 36.50 MPa, flexural strength of 4.52 MPa, and split tensile strength of 3.85 MPa, satisfying IS 456:2000 performance requirements. The CTW mix attained 31.19 MPa compressive, 4.44 MPa flexural, and 3.87 MPa tensile strength, indicating adequate performance for secondary structural elements. Durability assessments, conducted for RCA mixes, revealed strength losses of 7.95% in acid, 14.55% in chloride, and 14.58% in sulphate environments, alongside low permeability and retained integrity at 600°C. Environmental impact was quantified using both manual lifecycle calculations and One Click LCA software. Results demonstrated a 20.2% reduction in energy consumption and CO2 emission savings of 22.4% for commercial and 20.6% for residential structures. The findings confirm RCA’s structural and environmental suitability (94% compressive strength retention, CO2 savings up to 22.4%), while CTW showed acceptable strength for non-structural applications.