Investigating the effect of pumice as a supplementary cementitious material on the durability of calcium aluminate cement composite

Calcium aluminate cement is one of the special cements that performs much better than Portland cement in severe environmental conditions. Engineers, on the other hand, have been critical of this unique cement due to the loss of long-term strength and durability caused by the conversion phenomena. The goal of this study is to improve the durability of calcium aluminate mortar by replacing the cement with pumice powder. In this study, pumice was used as cement substitutes in proportions of 0, 5,15,25, 40, and 60%, and a total of 6 mortar mixes were developed and it was examined in terms of durability properties. The results showed that the plain mixture reached a compressive strength of 33 MPa at the age of 1 day, and 44MPa at the age of 28 days but at 90 days, due to the conversion phenomenon, its strength had decreased by 45%. Pumice had a considerable effect on the strength and, more significantly, the durability properties of mixtures by influencing the conversion phenomena. At the age of 90days, Compressive strength, chloride ion migration coefficient, and electrical resistance, for example, have improved 47%, 78%, and 400% in the ideal mixture (P40) compared to the plain mix. According to the review of the literature, the effect of replacing pumice with CAC cement has not been considered significantly and the effect of pumice on the durability of this type of cement has not been investigated, which can be considered an innovation of this study.