Characterization and properties of porous red mud–based geopolymer composites reinforced with carbon fiber powders

To obtain porous composites with high porosity and improved performance, porous geopolymer composites (CFP/RMG) were fabricated using alkali-excited red mud and carbon fiber powders (CFPs) using the foaming method. The synergistic effects of CFPs and H 2 O 2 on the microstructure, pore structure, strength, and thermal properties of the porous samples were systematically investigated. CFPs were uniformly distributed on the pore walls of the samples. The total porosity decreased with CFPs and increased with H 2 O 2 , the density of CFP/RMG samples ranged from 0.57 ± 0.01 to 1.71 ± 0.05 g/cm 3 . The compressive strength of the composite samples increased from 0.54 ± 0.09 to 4.16 ± 0.24 MPa with an increase in CFPs from 0 to 12.5 wt%, and it decreased from 4.06 ± 0.23 to 0.47 ± 0.06 MPa with 1–5 wt% H 2 O 2 . Fiber bridging and fiber pullout contributed to the strength reinforcement of the whole composite. The porous composites also showed low thermal conductivity (0.176–0.680 W/(m·K)), which revealed that it had potential applications in the field of building materials in the future. • Porous carbon fiber powders/red mud-based geopolymer composites were prepared. • Pore structure of the foamed composites was controlled by CFPs and H 2 O 2 . • Strength was improved by fiber bridging and pullout.