The Uses of Finely Ground Materials to Mitigate the External Sulphate Attack (ESA) on Cementitious Materials

Abstract

External sulphate attack (ESA) is a term used to describe various chemical reactions between sulphate ions and hydrated cement compounds. Thus, the chemical composition of the binder is extremely important on the durability of concrete structures and structural members exposed to sulphate environments. This paper aims to evaluate physical (i.e. induced expansion and compressive strength) and mineralogical (i.e. X-ray diffraction) properties of eight mortar mixtures presenting distinct compositions (i.e. OPC, Quartz and Limestone Fillers, Red-Clay Waste, Fly Ash, Metakaolin, Silica Fume and Rice Husk Ash) and exposed to two different 0.7 M sulphate solutions (i.e. sodium and magnesium). The results show that the remaining portlandite in the system plays an important role on the sulphate attack deterioration process and seems to be dependent on the type of sulphate attack. Moreover, the overall ESA damage was found to increase with the use of binders containing aluminum-silicate compounds.