Investigation on the effect of high level of usage of supplementary cementitious materials on the acid resistance, chloride ion permeability and microstructure of calcium aluminate cement-based mortars

Calcium aluminate cement (CAC) is considered as a specific cement due to its special properties and maybe have improved performances compared to the Portland cement under some severe conditions. Although alumina cement has many advantages, it is not widely used in the construction industry because it obtains reduced strength in the long term and has not been adequately investigated. In this study, an attempt is made to improve the durability and mechanical properties of mortars with this type of cement using supplementary cementitious materials (SCMs) such as pumice, zeolite and limestone powder in high cement replacement levels. In this study, porosity, rapid chloride migration and acid resistance tests were employed to investigate the durability properties. In addition, the microstructure of the mixtures was investigated using scanning electron microscopy (SEM). The SCMs were used as cement substitution in proportions of 25, 40, and 60 % and a total of 10 mortar mixes were investigated. The results indicated that the pumice and zeolite significantly improved the mechanical strength and durability properties of the mixes. The microstructural studies revealed one of the most important reasons for the reduction of the compressive strength of the plain mixture. The results of this study show that the use of pumice and zeolite mitigates the conversion process, resulting in better performance of the mixes compared to the plain mixture.