Influence of Critical Parameters of Mix Proportions on Properties of MK-Based Geopolymer Concrete

Conventional Portland cement concrete has been extensively used in the past century due to its superior performance compared to other building materials. Recognizing the environmental impact of cement composites and global pressure toward implementation of sustainable construction materials, geopolymer concrete has been introduced as a potential alternative to conventional cement concrete. This study investigates the properties of metakaolin-based geopolymer concrete by employing various mix design parameters based on locally sourced materials. The test results reported herein comprised 16 mixes divided into three groups to understand the influence of various parameters on the workability and compressive strength of the concrete and hence optimizing the mix proportions. The outcome of this research provided insights into the curing conditions, curing age, sodium hydroxide molarity, sodium silicate content, molar ratios of the mix, and aggregate water absorption effect on the geopolymer concrete behavior. A model is proposed for deciding the water to solids ratio based on the total aggregate percentage for workable geopolymer mixes. In order to produce MK-based geopolymer concrete for structural applications, thresholds are proposed for the three molar ratios, namely sodium oxide to silicon oxide, sodium oxide to aluminum oxide, and water to sodium oxide ratios.