Durability and Fire Performance of Gypsum Composites Reinforced with Recycled Polyethylene Fibers

Gypsum is a widely used building material because of its good non-structural performance and low cost. However, when exposed to moisture and other harsh environments, it may lose its strength. In this study, gypsum composites (GCs) reinforced with recycled polyethylene (PE) fibers from bird nets (BNs) were developed, exposed to wet–dry cycles and fire, and then mechanically tested to verify the influence of these exposures on their properties. The main highlights include: at 40% replacement of gypsum with BN fibers, surface hardness increased by 5%, and with a fiber content of 10%, the compressive strength showed a slight increase of 3%, and flexural strength decreased by only 9%. The 10 wet–dry cycles did not have much influence on the mechanical performance, unlike exposure to fire, which drastically reduced it. Moreover, open porosity was reduced by 19% and total water absorption by 17% with 40% BN fiber content, making them suitable as additives in GCs for application in humid environments.