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

Calcium aluminate cement is a special type of cement that does not have some of the mostimportant disadvantages of Portland cement. Calcium aluminate cement has some uniqueadvantages including high early strength, high resistance in acidic and chloride environments andhigh heat resistance. However, due to its long-term strength loss calcium aluminate cement is notwidely used in construction sector. The strength loss occurs due to the conversion phenomenon,which is thermodynamically unavoidable in calcium aluminate cement.This study aims at investigating the effect of pumice as a supplementary cementitious material onthe durability characteristics of calcium aluminate cement mortar. Despite many studies on binaryand ternary Portland cement, binary and ternary calcium aluminate cement has rarely been studied.In particular, the effect of pumice on the durability of this type of cement has not been studied,which can be considered an innovation of this study and even its results can be effective indeveloping standards for calcium-aluminate cement.In this study, pumice was used in substitution level of 5%, 15%, 25%, 40% and 60% of calciumaluminate cement and its effect on the durability of mixtures was investigated. The results showthat the plain mixture has high compressive strength (33 MPa) at one day; nonetheless byincreasing the ages up to 90 days it shows a decreasing trend due to the occurrence of theconversion phenomenon. The Analyses indicate that Pumice has a very significant effect on thestrength by controlling the conversion phenomenon, and, more importantly, improves thedurability properties of the mixtures. For instance, in the optimal pumice replacement level(40%), the chloride and electrical resistance improves 360% and 400% respectively in compare to plain mixture.

کلیدواژه ها:

Calcium Aluminate Cement ، Pumice ، Durability ، Supplementary cementitious material ، Conversion