A Comprehensive Review of Metakaolin-Based Ultra-High-Performance Geopolymer Concrete Enhanced with Waste Material Additives.

The present investigation reviews some of the recent research work focusing on developing the use of ultra-high-performance geopolymer concrete (UHPGC) with metakaolin (MK) as a binder, which garnered significant interest due to fulfilling the growing need for durable, cost-effective, and environmentally sustainable construction materials, as it has substantial advantages, including the capacity to generate superior thermo-mechanical properties and durability with less of an adverse environmental effect where materials are used that reduce carbon dioxide emissions (CO2), and studying the effect of its inclusion with fly ash (FA), ground granulated blast furnace slag (GGBFS), and silica fume (SF). Also, this review examines the impact of incorporating alkali activators, which are mixing solutions of sodium hydroxide (SH) and sodium silicate (SS), and powdered waste materials as replacement materials for aggregates and cementitious materials-specifically basalt waste powder (BWP), marble waste powder (MWP), glass waste powder (WGP), and granite waste powder (GWP)-into MK-based UHPGC. These waste powders, generated from industrial by-products, provide an ecological approach to enhance the characteristics of concrete while decreasing waste. The most noticeable improvement in mechanical performance among the materials examined is shown by basalt waste powder, especially in terms of compressive and flexural strength (CS, FS). This enhancement is attributed to its unique mineral composition and pozzolanic activity, which refine the microstructure and strengthen bonding within the concrete matrix. This review discusses the limitations and potential optimizations for incorporating these waste materials, positioning metakaolin-based UHPGC as a sustainable and high-performance alternative in construction. Future research should address long-term durability, performance consistency, and the establishment of standards for using waste powders in geopolymer concrete formulations. The creation of ultra-high-performance geopolymer concrete has received relatively little attention, even though several studies in the field of geopolymer technology have been conducted.