Abstract
The transition toward a circular economy in the construction industry necessitates the development of low-carbon materials that simultaneously address the management of construction and demolition waste (CDW). This study presents a comprehensive Life Cycle Assessment (LCA) of geopolymer concrete (GPC) incorporating recycled concrete aggregates (RCA) as a replacement for natural aggregates (NA). Using a cradle-to-gate approach, the environmental performance of various mix designs—including Ordinary Portland Cement (OPC) concrete, 100% GPC, and Recycled Aggregate Geopolymer Concrete (RAGC)—was evaluated. The study identifies the primary contributors to global warming potential (GWP) and other environmental impact categories such as acidification and eutrophication. Results indicate that while geopolymer binders significantly reduce embodied carbon compared to OPC, the alkaline activators remain a critical environmental hotspot. Furthermore, the integration of RCA offers a dual benefit: reducing the demand for virgin resources and lowering the net carbon footprint through the avoidance of landfilling and long-distance transport. Mechanical testing confirmed that RAGC can achieve structural-grade compressive strengths, although workability and long-term durability require careful activator optimization. The LCA results demonstrate a potential reduction in GWP of up to 45% for RAGC compared to traditional OPC-based concrete. These findings provide a quantitative basis for policymakers and engineers to adopt alkali-activated materials and recycled aggregates as a viable strategy for decarbonizing the built environment, aligning with global sustainability targets for 2030 and beyond.