Microstructure of red brick dust and ground basaltic pumice blended cement mortars exposed to magnesium sulphate solutions

This paper presents a laboratory study on the deterioration of blended cement combinations of plain Portland cement (PPC) with red brick dust (RBD) and ground basaltic pumice (GBP). The compressive strength and the magnesium sulphate resistance of cements have been experimentally determined. The development of the microstructure and the secondary minerals in the plain and blended cements were studied via scanning electron microscope (SEM) analysis. A series of mechanical tests of cement mortars were undertaken on all specimens. A large quantity of sheet-like C-S-H was found in the mortars that have developed by the addition of RBD and GBP. The results indicated that the increase in the additive content caused a significant increase in the sulphate resistance of the mortars. Hence, the studied RBD and GBP can be recommended for use as admixtures in cement production