Early metakaolin reactions in pozzolanic R3-test: calorimetry baseline correction of initial temperature jump due to ex-situ mixing

Abstract The increasing concerns regarding global warming and the scarcity of raw materials in construction industry have led to a growing need for alternative low-carbon binders partially replace ordinary Portland cement. To assess suitability pozzolans as supplementary cementitious (SCMs), R 3 -test has been introduced successfully validated wide range materials. This test provides an opportunity analyze reactivity classification study reaction mechanisms kinetics novel SCMs well-controlled environment. In this study, focus lies on evaluating early reactions lime paste samples through isothermal calorimetry tests conducted at 40 °C. However, conventional mixing methods present experimental challenges. In-situ fails achieve proper homogenization, while ex-situ results temperature difference start testing due elevated condition address these concerns, calorimetric methodology is proposed detection responses. main concept involves establishing baseline correction caused by mixing, which calibrated using inert sample. allows extraction heat generated reactions. Combined with Tian time correction, enables evaluation measured °C within first 100 min after mixing. effectiveness was demonstrated impact potassium sulfate three different types metakaolin.