Fire-resistant performance of new sustainable waste-lightened composites with glass and basalt fibres reinforcement

In recent years, numerous studies have been conducted on the incorporation of plastic wastes into gypsum or plaster compounds with the aim of achieving more sustainable and environmentally friendly materials. Despite the vulnerability of plastic materials to high temperatures, it is not common to analyze the behavior of these new compounds in case of a fire. In this study, different lightweight plaster compounds have been developed, partially replacing the original raw materials with plastic waste in dissolution up to 23.5% and reinforced with glass and basalt fibers. After exposing the compounds to real direct fire, mechanical characterization (flexural strength, compressive strength, surface hardness tests) and physicochemical characterization (XRD, TGA) have been carried out, including the calculation of CO and CO2 emissions associated with the combustion of the compounds, as well as imaging by scanning electron microscopy. The results show that the reduction in the density (between 15%-24%) of the new compounds favored lower temperatures during exposure to flames, preventing material cracking. Likewise, the new composites experienced a loss in flexural strength between 44%- 51%, and a drop in compressive strength between 2%- 63%, being these losses in strength lower than those experienced by the reference composites. The addition of glass fibers demonstrated to confer better flexural behaviour to the compounds with added waste, while the basalt fibers were more efficient in compression. Furthermore, the estimated toxic emissions produced during the combustion of the designed compounds did not exceed the immediately dangerous to life or health (IDLH) values established by the Material Safety Data Sheet (MSDS), remaining below 2000 ppm/h for CO and 40,000 ppm for CO2. This study contributes to a better understanding of the behavior of plaster compounds with incorporation of plastic waste in case of fire, highlighting the developed materials as a viable alternative for the production of more environmentally friendly prefabricated products.