Metakaolin-Based One-Part Geopolymer Concrete: A Review

Metakaolin-based geopolymer concrete (MK-GPC) is an advanced sustainable binder system that can significantly mitigate carbon emissions associated with conventional Portland cement production. This paper provides an in-depth research review of recent developments (2020–2025) in MK-GPC focusing on mix design strategies, reaction mechanisms, mechanical and microstructural behaviour, and sustainability analysis. The review integrates quantitative data from laboratory investigations and reaction kinetics to describe how key parameters—such as Si/Al ratio, NaOH molarity, Na₂SiO₃/NaOH ratio, and liquid-to-binder ratio—affect geopolymerization. Results from multiple studies show compressive strengths ranging between 40–80 MPa, enhanced microstructural density, and 40–60% lower CO₂ emissions compared to OPC. Despite its proven mechanical and durability advantages, MK-GPC still faces challenges related to cost, activator sustainability, and field standardization.