Mitigating high-temperature vulnerabilities in concrete: utilizing waste plastic fibers for enhanced mechanical resilience and environmental sustainability

The susceptibility of concrete to elevated temperatures is a paramount concern in civil engineering, especially in fire-related scenarios. This material often suffers mechanical weaknesses such as fracturing and reduced durability under high temperatures. Despite its ubiquitous use, concrete’s vulnerability to thermal stress presents significant challenges for maintaining structural integrity and safety. The novelty of this work lies in its innovative approach to addressing these challenges by proposing the utilization of waste plastic fibers, which are readily available due to the extensive use of various plastic products. This approach not only enhances the mechanical resilience of concrete but also contributes to mitigating environmental and health impacts associated with plastic waste. The research focuses on the effects of high temperatures on the mechanical properties of sand concrete reinforced with fibrous materials. Concrete specimens were prepared with different lengths (1 cm and 2 cm) of packing tape fibers at concentrations of 1% and 2%. These specimens underwent controlled thermal treatments ranging from 100 °C to 700 °C with a heating rate of 1 °C/min, following a 90-day water immersion curing period. The evaluation encompassed various tests including visual inspection, residual weight measurement, residual compressive and tensile strength assessments, and ultrasonic pulse velocity (UPV) testing. The analysis revealed a notable improvement in mechanical strength for concrete reinforced with 1% fibers at 300 °C. However, exposure to higher temperatures (500 °C and 700 °C) led to a significant decline in strength across all samples due to the evaporation of fibers, resulting in the formation of voids and conduits within the concrete’s structure. While previous research has extensively investigated the effectiveness of polypropylene fibers in crack mitigation during fire incidents, limited attention has been given to the potential of plastic waste as a reinforcement material. Thus, this study’s novelty contributes to expanding the scientific understanding of using waste plastic fibers to enhance concrete’s resilience to high temperatures, thereby filling a crucial gap in existing literature.