Fiber-Reinforced One-Part Geopolymer Mortars Incorporating Red Mud, Ceramic Powder, and MgO: Performance Under Different Curing Regimes and Curing-Based Environmental Assessment

One-part geopolymer mortars provide an alternative to cementitious materials by using dry activators and industrial by-products. This study evaluated a multi-precursor matrix containing slag, fly ash, ceramic powder, red mud, and 5% MgO, reinforced with polyvinyl alcohol (PVA), basalt, or micro-steel fibers at 0.4% and 0.8% by volume. Specimens were cured at 20 ± 2 °C or at 80 °C for 24 h and assessed for flowability, mechanical properties, ultrasonic pulse velocity (UPV), Böhme abrasion, 24 h water absorption, and sorptivity. XRD, FTIR, and SEM/EDS were used only to compare by heat-cured mixtures. The results showed that at 28-day, heat curing increased compressive strength by 39.5–71.8%, flexural strength by 29.2–134.4%, and UPV by 20.5–36.4%, while reducing sorptivity by 12.2–35.7% relative to ambient curing. PVA reduced flowability likely because of its hydrophilic surface and high surface area. For 0.8PVA, the flow diameter was 23.6% below the reference, whereas the 28-day heat-cured flexural strength reached 7.5 MPa, with the lowest abrasion thickness loss of 0.63 mm. Micro-steel mixtures maintained compressive strength comparable to the reference, reaching 72–73 MPa at 28-day. Heat curing reduced water absorption in PVA and basalt mixtures, whereas the reference and micro-steel mixtures showed insignificant change. Microstructural analyses suggested the formation of a more compact and reacted aluminosilicate matrix under heat-cured conditions. A screening life-cycle assessment, limited to the non-fiber-reinforced reference matrix, showed that heat-curing increased global warming potential by 7.6%, while the two solid activators contributed approximately 45% of the ambient-cured reference GWP. The findings indicate that heat curing significantly enhances the performance of one-part geopolymers, while fiber selection provides additional mechanical and durability improvements.