Effects of elevated temperatures on residual properties of concrete reinforced with waste polypropylene carpet fibres

In this study, the effect of waste polypropylene carpet fibres and palm oil fuel ash (POFA) on the mechanical and microstructural properties of concrete exposed to elevated temperatures was investigated. Concrete samples were exposed to high temperatures up to 800∘C then cooled to ambient temperature before tests. Four mixes containing carpet fibres (0 and 0.5%) and POFA (0 and 20%) were prepared. Mass loss, residual ultrasonic pulse velocity, compressive strength, scanning electron microscopy, X-ray diffraction and differential thermal analysis were performed to investigate the effects of carpet fibres and POFA on the performance of the concrete at elevated temperatures. The results showed that both carpet fibres and POFA were associated with a significant enhancement in the fire resistance and residual compressive strength and also eliminating the explosive spalling behaviour of the concrete at elevated temperatures. Furthermore, the role of carpet fibres and POFA is discussed through the microstructural analysis and fibre–matrix interactions as function of heat treatment