The durability of cement-based materials is always known as one of the main constituents of the sustainability of infrastrustures and urban structures because of its copious application. One of the ways to enhance concrete’s durability, especially in corrosive environments, is to use natural pozzolans. On the other hand, nowadays, investigating the effect of carbonation on the durability of concrete has gained much importance due to the increase in the carbon dioxide emission in cities. In this paper, the effect of carbonation on the durability properties of natural pozzolan containing mortars has been investigated. In order to prepare the mixtures, two natural pozzolans, Jajrood Trass and Khash Pumice, have been used as the supplementary cementitious materials with substitution amount of 20 percentage of the cement’s weight and also three water to binder ratios of 0.485, 0.44, and 0.4 have been utilized. The compressive strength test has been operated to investigate both the mechanical properties and the hydration development of the mortars in disparate ages. In order to investigate the durability properties of the mortars, carbonation depth, sorptivity, and electrical resistivity have been measured.
The results relates that the addition of natural pozzolans has reduced the compressive strength of mortars, however, it has augmented the carbonation depth of the specimens, while, the electrical resistivity has been increased. The sorptivity test outcomes show that in some specimens, carbonation has decreased the absorbtion coefficient but in some other specimens, it has increased it. Finally, it can be concluded that Trass containing mortars have better performance in early ages compared to Pumice containing mortars, whereas, when the specimens’ age increase, the Pumice containing mortars evince a better performance and it is expected from them to outperform Trass containing mortars in later ages.