Influence of Supersulfated Cement Composition on Hydration Process

Abstract

In recent years, considerable attention has been given to the development of special cements capable of reducing CO2 emissions as well as energy and limestone consumption. One option is the use of supersulfated cements (SSCs). SSCs are primarily comprised of blast-furnace slag (80%–85%), calcium sulfate (10%–15%), and an alkaline activator, which is often portland cement, though in a relatively small quantity (around 5%). In this paper, the effects of the proportions of SSC (slag, calcium sulfate, and alkali activator contents) were studied for two slags with different chemical compositions, mainly the Al2O3 content. The results showed the slag characteristics and the alkaline activator content played a very important role in the process of hydration. The SSC made using high-alumina slag exhibited higher compressive strength (55 MPa at 28 days with 88% slag) and the use of higher activator contents decreased the compressive strength, heat release, ettringite formation, and degree of hydration.