Degradation Potential of Metakaolin-Based Geopolymer Composites Immersed in Real and Simulated Acidic Environments

This study investigates the degradation potential of metakaolin-based geopolymer (GP) composites when exposed to real and simulated acidic environments. Traditional OPC concrete, commonly used in wastewater treatment facilities, faces considerable deterioration due to the destructive chemical composition of municipal wastewater. This extensive investigation aims to assess the performance of GP composites as a sustainable alternative to such materials. The metakaolin-based GP mortar samples were prepared and subjected to immersion in a primary clarifier unit at a local wastewater treatment plant (real) and a laboratory-made acetic acid solution (simulation) for up to four weeks after curing. The analysis included measurements of % strength and % weight loss, as well as characterization techniques such as isothermal calorimetry, microstructure (SEM), and mercury porosimetry (MIP). The outcomes signified a cumulative heat generation of 534 J/g at three days, with an average compressive strength of 79.4 MPa past 28 days. Exposure to acetic acid led to a 13% decline in compressive strength and a 3.90% loss in sample weight, while exposure to real wastewater resulted in an 18% strength and a 5.60% weight loss. Observations from SEM revealed microstructural changes, including the formation of biofilms and air voids, indicating multifaceted interactions between the GP matrix and its surrounding environment. This research effectively highlights the potential of metakaolin-based geopolymer composites to improve durability against acidic conditions, suggesting future applications in the construction of infrastructure exposed to such harsh chemical environments.