Development of high-performance one-part geopolymer foam concrete using ground granulated blast furnace slag, waste concrete sludge, and bamboo powder for sustainable construction

One-part geopolymer foam concrete (GFC) represents a sustainable alternative to traditional cementitious materials. This study investigates the influence of waste valorization on the performance of GFCs using ground-granulated blast-furnace slag (GBFS), waste concrete sludge (WCS), and waste bamboo powder (WBP), activated with sodium metasilicate. The GFCs were thermally cured and evaluated for workability, mechanical properties, durability, and microstructural changes. Mixes were characterized by compressive strength, flexural strength, density, water absorption, shrinkage, freeze-thaw durability, high-temperature resistance, and thermal conductivity. The results show that mix 0CS-BP5, containing 5 % WBP and no WCS, achieved the highest compressive strength (7 d: 7.6 MPa, 28 d: 11.4 MPa) and flexural strength (28 d: 1.2 MPa) owing to improved pore structure and crack-bridging from WBP. The incorporation of WBP reduced water absorption by 39 % and 91-day drying shrinkage by 52 % compared to the control mix (0CS-BP0). Thermal conductivity ranged from 0.32 to 0.43 W/m·K across mixes, offering a balance between insulation and mechanical strength. Mix 0CS-BP5 exhibited superior freeze-thaw durability, with only 3.6 % mass loss after 50 cycles. Furthermore, it retained 3.0 MPa compressive strength at 750° C, indicating enhanced high-temperature resistance. However, mixes with higher WCS content (e.g., mix 25CS-BP5) showed a decline in strength and transport properties due to their heterogeneous structure and increased macro-void connectivity. This study demonstrates the potential of utilizing industrial and biowaste to develop high-performance, low-carbon GFCs, advancing the use of sustainable materials for energy-efficient and durable construction applications.