The Impact of Molar Proportion of Sodium Hydroxide and Water Amount on the Compressive Strength of Slag/Metakaolin (Waste Materials) Geopolymer Mortar

Abstract

This investigation aimed to improve great early geopolymer mortar strengths under various parameters with various binder proportions to reduce the use of cement since the OPC production process leads to high emissions of CO2. Hence, to solve this problem, alternative materials were used. In this research, metakaolin (MK) and ground-granulated blast-furnace slag (GGBFS) waste materials were utilized and mixed together with the sodium hydroxide and alkaline activator sodium silicate (NaOH and Na2SiO3). The performance of the various mixtures was assessed via compressive strength testing based on British standards. The compressive strength was found to be highly affected by molar proportion and water amount. The optimum strength was 77.8 MPa for a mix design of 95% GGBFS +5% MK and a 2.5 mass proportion between Na2SiO3 and NaOH (12 Molar), together with a 0.2 water/binder proportion.