Sustainable Cementitious Material with Ultra-High Content Partially Calcined Limestone-Calcined Clay

The application of calcined clay and limestone powder in cementitious materials to partially substitute ordinary Portland cement is regarded to be highly potential for developing sustainable green building materials. However, with the increase of substitution level, the major drawbacks include the slow development of the early strength and the decrease of the later strength. In this study, the limestone is partially calcined to form the core-shell structure with loose calcium oxide on the outside and dense calcium carbonate on the inside, and sustainable cementitious material with ultra-high content partially calcined limestone and calcined clay (substitution level is up to 80%) is developed. It is evident from this study that the core-shell structure of partially calcined limestone promotes the formation of a dense layer of hydration products, and exhibits great advantages in activating the reaction of calcined clay and improving the strength development of the cementitious materials that are 90% and 137% higher than that of cementitious material with the limestone-calcined clay at 7d and 28d, respectively.