The construction industry generates more than ten billion tonnes of construction and demolition waste annually, and in Kuwait alone C&D material accounts for roughly half of the national waste stream. This study investigates whether recycled concrete aggregate (RCA) — the same crushed material currently sent to landfill — can serve as a structural-grade replacement for natural coarse aggregate.
Six concrete mix designs were prepared at replacement levels of 0%, 20%, 40%, 60%, 80%, and 100%, cast as 4×8 in. cylinders, and tested per ASTM C39 after a 28-day curing period. The 40% replacement mix outperformed the control, with replacement levels above that threshold introducing significant variability tied to adhered mortar and excess fines. Findings align with ACI 318 guidance and frame RCA as a credible pathway for Kuwait’s 2040 Waste Management Strategy.
“Concrete production can be more environmentally and economically efficient without sacrificing performance — the data points clearly to a 40% RCA replacement as the practical optimum.”
5,676 psi
Avg. compressive strength at 40% RCA — highest of all six mixes tested
39.6%
Reduction in carbon emissions vs. natural aggregate (Neupane et al., 2025)
53%
Share of Kuwait’s national waste stream made up of C&D WASTE
Sustainable Materials
ASTM C39
ACI 318
Circular Economy