Precursor source-independent geopolymer formulation for achieving target strength

Among the key challenges limiting the scalable adoption of geopolymers is the absence of a rigorous material design framework to ensure consistent performance, as their properties are intrinsically governed by the compositionally heterogenous and regionally sourced aluminosilicate precursors. This study introduces a performance-based geopolymer mix design methodology that achieves target mechanical strength across diverse metakaolin sources. Five commercially sourced metakaolins were investigated alongside laboratory-calcined kaolin with fully controlled thermal histories as a reference. Reactive phase contents were comparatively quantified via X-ray diffraction, nuclear magnetic resonance, dissolution test, and inductively coupled plasma optical emission spectroscopy. The results showed that conventional X-ray fluorescence-based design fails to capture precursor heterogeneity, leading to significant strength variability across different precursor sources. By incorporating reactive phase content, adjusting water-to-solid ratio via inert fillers, and particle size refinement into material design, the strength reproducibility markedly enhanced and sensitivity to precursor variability substantially reduced.