Self-compacting ultra-high-performance geopolymer concrete: influence of alkaline activator and curing regime

This study aims to critically investigate the development of self-compacting ultra-high-performance geopolymer concrete (SCUHPGC), with a particular focus on the influence of the type of alkaline activator and curing regime on mechanical performance, embodied CO2 emissions, and cost efficiency. A detailed comparative analysis was conducted between ambient-cured mixtures activated by a sodium hydroxide (SH)-sodium silicate (SS) mixture versus combined-cured mixtures (a 90°C hot water followed by 250°C dry-air curing) activated by calcium carbide residue (CCR). The ambient-cured SH-SS-activated mixtures were designed using a ternary binder, achieving a slump flow diameter of 740 mm and a compressive strength of 132.7 MPa. The CCR-activated mixtures reported in the literature consisted of a binary binder. It was reported that under combined curing conditions, the plain CCR-activated mixture achieved a slump flow diameter of 700 mm and a compressive strength of 130.4 MPa. The total carbon dioxide equivalent (CO2-e) emissions and production cost of the ambient-cured SH-SS-activated SCUHPGC were lower than the corresponding total CO2-e emissions and production cost of the combined-cured CCR-activated SCUHPGC by approximately 15.9% and 13.5%, respectively. The ambient-cured SH – SS-activated SCUHPGC demonstrates superior efficiency, combining ultra-high mechanical performance with a lower environmental impact.