INTERACTION OF COMMERCIAL SUPERPLASTIFICANT ADDITIVES WITH POZOLANIC CEMENTS CONTAINING CALCINED CLAY

The utilization of polycarboxylate-based superplasticizer additives (PCE) in the concrete industry is widespread, and therefore, the dispersion mechanisms of these additives in cements containing supplementary cementitious materials (SCMs) present significant opportunities for investigation. This article aims to characterize the interaction between three commercial PCEs and three types of cement (pure Portland cement CPV-ARI and cement formulations containing 20 wt% and 28 wt% calcined clay content). The cement and calcined clay underwent physical-chemical characterization, whereas the PCEs were characterized through solid content determination and FTIR analysis. The interaction between cement, SCMs and additive was assessed by determining the optimal additive dosage using the mini-slump test, which was employed to evaluate its influence on kinetic mechanisms and hydration using a semi-adiabatic calorimeter, as well as mechanical strength. The PCEs exhibited high sensitivity to calcined clay, requiring higher dosages of PCEs to achieve the same fluidity compared to the system without clay.