On the relationship between superplasticizer demand and specific surface area of calcined clays in LC3 systems

Abstract

Calcined clays have received significant attention as a primary supplementary cementitious material (SCM) for reducing the CO2 footprint of cement, especially when combined with limestone in limestone calcined clay cement (LC3). However, it is widely recognized that the use of calcined clays leads to increased water and admixture demand, posing challenges in terms of slump-retention and rheology when using conventional admixtures developed for OPC. Superplasticizer demand is commonly correlated with the kaolin content of the raw clays. In this paper, we investigate and demonstrate the strong influence of the specific surface area of calcined clays on superplasticizers dosage by studying four different LC3 compositions ranging from 65% to 35% clinker content, using five calcined clays and two superplasticizers.