Clays, Chemistry, and the Clock: Accelerating Reactivity Insight in low-carbon cement design.

The cement industry is urged to reduce CO₂ emissions, with clinker substitution by supplementary cementitious materials (SCMs) representing the most effective strategy. However, as the availability of traditional SCMs such as fly ash and blast furnace slag progressively diminish, there is a need to identify and evaluate alternative SCMs. This highlights the importance of fast methods to assess SCM reactivity, particularly given their inherent variability. While current methods, such as the Rapid, Relevant, Reliable (R3) test, correlate well with strength development, their extended duration (7 days) limits their applicability for at-line industrial use. To address this limitation, the DETOCS project under DC13 introduces the Ultra Rapid Reactivity (UR2) test, a novel method that can assess SCM reactivity in 5 minutes and showcases its application to an industrial calcined clay. In short, the UR2 test exhibits strong correlation with both the R3 and 28-day compressive strength, supporting its potential as a rapid and robust tool for real-time quality control of SCMs in industrial production facilities.