Fly ash and waste brick powder-based one-part geopolymer foam concrete with enhanced thermal performance: A circular approach to construction and demolition waste utilization

Cement production's environmental impact necessitates sustainable alternatives. This study develops one-part geopolymer foam concretes (GFC) incorporating waste brick powder (WBP) and recycled fine aggregates (RFA) to address construction waste valorization and carbon reduction. Mechanical, thermal, and freeze-thaw durability properties were evaluated across WBP (0-40 %) and RFA (0-100 %) replacements. Results demonstrate that 40 % WBP (B40R0) achieves optimal mechanical performance, yielding 13 % higher 28 days compressive strength (4.5 MPa) and 14 % lower porosity (28.3 %) compared to the control mix, attributed to WBP's high Al2O3 content enhancing geopolymer crosslinking. Conversely, 100 % RFA (B40R100) minimizes thermal conductivity (0.246 W/m & sdot;K) but reduces 28 days compressive strength compared to the control mix due to interfacial porosity. Thermal durability tests (200-800 degrees C) reveal WBP-rich mixes retain structural integrity via crystallization, while freeze-thaw cycles show RFA increases mass loss (19.1 % after 50 cycles). The findings validate WBP-RFA geopolymers as viable for nonstructural applications, balancing thermal insulation (RFA) and mechanical robustness (WBP), advancing circular construction strategies.