Influence of Waste Glass Particle Size on the Physico-Mechanical Properties and Porosity of Foamed Geopolymer Composites Based on Coal Fly Ash

In order to protect the environment and counteract climate change, it is necessary to take any actions that enable a reduction in CO(2) emissions. One of the key areas is research focused on developing alternative sustainable materials for construction to reduce the global demand for cement. This work presents the properties of foamed geopolymers with the addition of waste glass as well as determined the optimal size and amount of waste glass for improving the mechanical and physical features of the produced composites. Several geopolymer mixtures were fabricated by replacing coal fly ash with 0%, 10%, 20%, and 30% of waste glass by weight. Moreover, the effect of using different particle size ranges of the addition (0.1–1200 µm; 200–1200 µm; 100–250 µm; 63–120 µm; 40–63 µm; 0.1–40 µm) in the geopolymer matrix was examined. Based on the results, it was found that the application of 20–30% of waste glass with a particle size range of 0.1–1200 µm and a mean diameter of 550 µm resulted in approximately 80% higher compressive strength in comparison to unmodified material. Moreover, the samples produced using the smallest fraction (0.1–40 µm) of waste glass in the amount of 30% reached the highest specific surface area (43.711 m(2)/g), maximum porosity (69%), and density of 0.6 g/cm(3).