Effect of sodium sulfate in a mortar incorporating metakaolin

Abstract: Metakaolin is a pozzolanic addition, it was developed as a partial substitution of cement to reduce cement consumption and improve the durability of concrete. However, the incorporation of metakaolin introduces, at early age, a lack of mechanical performance of concretes at room temperature.This work aims to chemically activate metakaolin in cement past in such a way that, the same early age performance can be achieved in concrete as achieved without metakaolin. The study was carried out at cement mortar to observe the influence of sodium sulfates on compressive strength. The increase in resistance at early age was observed with the activation of metakaolin. The metakaolin activation was confirmed in cement matrices by physio-chemical analyses. The increase in compressive strength at early age can be explained by a decrease of porosity and setting time, an increase in the amount of C-S-H and a decrease in the amount of CH .