Hydration and phase assemblage of ternary cements with calcined clay and limestone

This study aims to understand the impact of calcined clay, limestone and gypsum on the hydration mechanisms and phase development in limestone calcined clay cement (LC3). Crushed quartz was used as an inert filler to isolate the individual impact of calcined clay and limestone in LC3 systems. The hydration and the microstructure development in these systems were studied using X-ray diffraction (XRD), isothermal calorimetry, scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP) as well compressive strength experiments. The presence of calcined clay helped in achieving a well-refined microstructure in LC3 within 7 days of hydration. A reduction in the degree of hydration of clinker phases was observed due the presence of calcined clay. The AFt/AFm phase assemblage was seen to depend on the blend composition. Additional ettringite was seen to form when the amount of gypsum was increased in the LC3 system. However, the increased gypsum content also resulted in the reduction in reactivity of limestone. (C) 2019 Elsevier Ltd. All rights reserved.