A Novel Type of Alkaline Activator for Geopolymer Concrete Based on Metakaolin

In recent years, geopolymers, as a new class of green cement binders, have been considered as an environmental-friendly alternative to Ordinary Portland Cement (OPC), which can potentially reduce negative environmental impacts of OPC, including carbon footprint and energy consumption. In this experimental research, effects of different alkaline activator solutions on the compressive, indirect tensile, and flexural strengths, water absorption, and resistance to an acidic condition of metakaolin-based Geopolymer Concrete (GPC) were investigated. Furthermore, a novel type of alkaline activator for GPC was introduced. In this regard, GPC specimens based on metakaolin were manufactured and cured at 90 ˚C. The results showed that the addition of NaOH to the mix after 3 min of mixing KOH and Na2SiO3 with dry components (1/3 of the total mixing duration) resulted in the highest compressive, tensile, and flexural strengths as well as the lowest water absorption capacity and weight loss under acidic condition, amongst other cases