Environmental Assessment of Waste-Derived Materials in 3D Concrete Printing and Cast-in-Place Construction Through a BIM-Integrated Multi-Scale Life Cycle Assessment Framework (2026-02)¶

The construction sector urgently requires low-carbon and resource-efficient alternatives to conventional OPC-based mortar/concrete. Ordinary Portland cement (OPC) production remains one of the most carbon-intensive industrial processes, while construction and demolition waste (CDW) continues to grow worldwide, undermining circular economy goals. This study addresses both challenges by integrating CDW-derived alkali-activated binders (AABs) with 3D concrete printing (3DCP) and evaluating the environmental performance through a two-stage life cycle assessment (LCA) consistent with ISO 14040/44 and EN 15978. Stage 1 compares the cradle-to-gate impacts of CDW-based AABs with an OPC-based reference mortar and a geopolymer reference mortar. Stage 2 links Building Information Modeling (BIM) and LCA to quantify the cradle-to-handover impacts of a single-storey 3D-printed building against a functionally equivalent cast-in-place (CIP) reference building. Results indicate that optimized CDW-based alkali-activated mortars can reduce global warming potential by up to 80% relative to the OPC-based reference, while 3DCP further reduces building-scale impacts by nearly 90% through formwork elimination and material efficiency. Material production remains the dominant hotspot for both systems, with alkaline activators identified as key contributors. Overall, coupling waste-derived binders with digital additive manufacturing provides a viable pathway toward circular, low-carbon construction and supports global decarbonization targets for the built environment.