Mechanical Performance of Sustainable Geopolymer Lightweight Concrete Exposed to Fire

The need for sustainability and reduced CO2 emissions is leading to increased use of industrial waste and byproducts from the building industry. Geopolymer concrete, is an environmentally sustainable alternative to conventional Portland cement binders and preserves the natural resources. This study presents the mechanical properties of specimens subjected to fire, with the samples being exposed to fire at temperatures of 400 °C, 600 °C, and 800 °C for 1 h in a period of 56 days. The results reveal a drop in the mechanical properties as the temperature increases, with the most significant deterioration taking place at 800 °C. The greatest reduction in compressive, splitting tensile, and flexural strength was observed in the unreinforced control mix at higher temperatures, while the specimens reinforced with 1% basalt fiber showed minimal strength degradation, indicating enhanced fire resistance and structural integrity under thermal conditions.