Study Durability of Mortars with Natural Pozzolans under Carbonation

Durability of cement based material due to its uses in the building industry, always has been recognized as one of the main components of sustainable development of infrastructure and urban buildings. One way to improve the durability of concrete, especially in corrosive environments is to use natural pozzolans. On the other hand, with increasing carbon dioxide gas production in cities, the effects of carbonation phenomenon on the durability properties of concrete have increased. In this research, the effect of carbonation phenomenon on the durability properties of mortars containing natural pozzolans is investigated. In sample making two natural pozzolans including Khash pumice and Jajroud trass as substitute for cement by 20% and three water/cement ratios of 0.485, 0.44 and 0.4 were used. In this study, compressive strength test was used as an indicator of mechanical properties as well as an indicator of hydration degree in specimens. In order to study of durability properties of mortars carbonation depth, water absorb capillary and electrical resistance of specimens were measured. According to results, use of natural pozzolans reduces the compressive strength of specimens and increase depth of carbonation in them. Also, electrical resistance increases in samples. The results of capillary absorb water test show that carbonation phenomenon decreases capillary absorption coefficient in some samples. Finally, it can be concluded that the trass samples showed better performance than the pumice at an early age, while the pumice improved with increasing age. It is expected that the pumice performance was better than the pumice with give over time