Advancing the Use of Supplementary Cementitious Materials: A Novel Framework for Quantitative Reactivity Estimation

The partial replacement of Portland cement (PC) with supplementary cementitious materials (SCMs) presents an effective strategy to reduce CO2 emissions associated with cement production while preserving essential mechanical properties and durability. SCMs, such as fly ash, blast furnace slag, calcined clays, and other aluminosilicate-rich materials, enhance sustainability through their pozzolanic and hydraulic reactivity. Despite their significant potential, the widespread adoption of SCMs has been limited by the absence of straightforward and quantitative methods to assess their reactivity‒a crucial property influenced by chemical composition, amorphous content, and particle fineness. To overcome these challenges, this study proposes a novel, simplified quantitative method for evaluating the time- and composition-dependent reactivity of SCMs in a PC-like environment. The approach combines isothermal calorimetry with detailed composition-based reaction enthalpy calculations, providing a robust framework for reactivity assessment. The method was applied to 17 chemically diverse SCMs, yielding reactivity values ranging from 9.3% to 63.2% at 7 days. Analytical models developed in the study reveal the relationships between the chemo-structural parameter (number of constraints, nc), heat release, and reactivity, enabling preliminary predictions based on chemical composition or calorimetric data. Validation across a broad spectrum of SCMs, including slags and calcined clays, confirms the reliability and versatility of this proposed methodology. This cost-effective and straightforward approach offers quantitative insights into SCM reactivity, enabling better control over binder properties and supporting the advancement of sustainable cementitious materials. The findings hold significant implications for optimizing SCM usage and advancing the design of environmentally sustainable construction materials.