Effects of clinker and calcined clay mineralogy on the hydration of limestone calcined clay cement (LC3)

The effects of Portland clinker and calcined clay (CC) mineralogy on the hydration of limestone calcined clay cement (LC 3 ) were investigated. Three clinkers with high/low C 3 S and C 3 A contents were combined with three CCs with different kaolinite contents (47, 80, and 98%). Comprehensive CC characterization, isothermal calorimetry, synchrotron and laboratory in-situ and ex-situ XRD, SEM-EDS, and compressive strength tests were conducted. CC47 and CC80 led to equivalent sulfate demands and comparable hydration kinetics, despite the large differences in composition and surface area. 27 Al NMR revealed the predominance of more soluble Al [V] sites in CC47, which did not have a significant impact on early-age hydration. The aluminate content in clinker did not govern sulfate demand; instead, the clinker with the smallest alite crystal size and low C 3 A content led to the highest sulfate demand. Specific clinker + CC combination allowed CC47-containing samples to reach strengths comparable to those obtained with CC80.