Phase Analysis and Microstructural Characterization of High Flexural Strength Eco-Friendly Geo Polymer Construction Block Made from Local Waste Material

This research aims to improve the production of geopolymer composites with high tensile strength by utilising local waste resources in Pakistan. Pakistan produces over 49.6 million tonnes of solid waste annually. In this study, we look into the possibility of using local waste streams as raw materials for synthesising geopolymer composites. The investigation thoroughly addresses the formulation of geopolymer matrices, including the precise selection of precursors, activators, and curing conditions according to the region's distinct waste sources. The study's findings encourage a circular economy and sustainable development by demonstrating how locally generated waste resources may be converted into useful building materials. After increasing polyvinyl alcohol content from 0% to 1% in 17 mol/dm3 concentration of NaOH, the material's flexural strength was 4 to 6 MPa. In 17 mol/dm3 concentration of NaOH, the material's compressive strength rises from 30 to 45 MPa upon increasing the PVA fiber content from 0% to 1%. Maximum mechanical strength is achieved at a concentration of 17 mol/dm3 of NaOH. The mechanical strength decreases as the concentration of NaOH rises. Although, geopolymer matrix is mostly amorphous, some crystalline phases may be present, including calcite, quartz, and gehlenite. The findings of these experiments indicate that PVA fibres have little effect on the phase composition of the geopolymer matrix. They improve the composites' mechanical properties by bridging the cracks and preventing their spread. As the SEM data shows, by bridging cracks and stopping their propagation, PVA fibres helped the composite's enhanced toughness. The flexural strength of 4.5 MPa (15% reduction) was found after performing a freeze-thaw cycle. The compressive strength reduces from 35 to 32 MPa with an average mass loss of 3% after performing a salt spray test. The blocks were immersed in water for 24 hours. The water absorption of 8% was measured, indicating effective moisture resistance.