14 - Sulfoaluminate cement-based concrete

Abstract

Sulfoaluminate cement (SAC) has been known as a low carbon and energy cementitious material as it can be produced at lower temperature, lower lime content, and improved grindability compared to ordinary Portland cement (OPC). The benefits are not limited to energy savings and low carbon emissions. In fact, SAC has promising properties that can overcome certain limitations of OPC. For example, shrinkage leading to cracks can be overcome using calcium sulfoaluminate (4CaO·3Al2O3·SO3). A ternary system of SAC with other cement phases such as dicalcium silicate and calcium aluminoferrite is more practical. Fast setting and early strength development can be accomplished rapidly due to ettringite (6CaO·Al2O3·3SO3·32H2O) formation. Such quick setting is one of the important properties for repair works. However, the cost of SAC is still unattractive for the construction industry due to the unavailability of raw materials. Understanding its behavior when applied to reinforced concrete is also a big issue, due to its low alkalinity that favors corrosion of steel. The replacement of OPC by SAC is, therefore, hindered in some circumstances. In order to approach sustainability for the future of the construction industry, this chapter discusses the synthesis of SAC using primary and alternative raw materials, its hydration reaction with the presences of admixtures and OPC, its durability, and its usages for concrete repair.