Effect of geopolymer alkaline activators on mechanical properties and durability of pozzolanic concretes

Simultaneous use of pozzolans and geopolymers to improve the properties of concrete is one of the relatively new areas of concrete technology. In this study, slag and zeolite pozzolans were used as a substitute for different percentages of cement weight in concrete. Alkaline activator was also used to reduce the negative effects of high percentages of pozzolan replacement and to investigate their interactions. Based on the results of the defined tests, it was found that the addition of activator to the concrete containing pozzolan had a significant role in recovering part of the loss of properties due to high consumption of pozzolan. By adding activator to the design containing 60% slag, an increase of 52.1% in compressive strength and 44.7% in electrical resistivity for 28 days was observed. Also, the mix design containing 60% zeolite, which had the highest decrease in compressive strength by 59.3%, led to the improvement of thermal insulation properties of concrete up to 14.3% compared to the control mix design.