The Mechanical, Physical, and Durability Properties of Low Alkali Solution Alkali-Activated Metakaolin: Assessing its Viability for Use with Steel Reinforcement

Abstract

Ordinary Portland Cement (OPC), the world’s most widely utilized construction material, contributes roughly 8% to global CO2 emissions during its production. This environmental strain and escalating global demand emphasize the urgency to explore alternative cementitious materials. Given its high strength and relatively minimal CO2 emissions, alkaliactivated metakaolin (AAMK) is a promising substitute for OPC. AAMK has the potential to impact the carbon emissions of the cement industry substantially. This thesis focuses on improving the physical, mechanical, and durability properties of AAMK. In pursuit of this goal, eight different mix designs were formulated. This involves introducing magnesium oxide and calcium hydroxide into the mix design, along with adjustments to the activator’s molarity. The values for Young’s modulus, compressive strength, porosity, and chloride penetration are compared to OPC to determine if AAMK is a viable material for steel reinforced structures. The results revealed a correlation between the molarity of activating solution and mechanical properties. Despite exhibiting lower carbon emissions, the 6M mix designs consistently fell short compared to their 8M counterparts. However, the incorporation of 5% magnesium oxide resulted in an enhancement of these properties, bringing them closer to those of the 8M mix designs. An analysis comparing the different data on each sample type was conducted to identify the optimal AAMK mix design. While 6M 5% MgO and 8M 0% MgO were found to be optimal, all 8 mix designs chosen were within an adequate range of OPC while still maintaining a reduced emissions cost.