Evaluation of the effective mechanical properties of concrete composites using industrial waste carpet fiber

Synthetic waste fibers are cheap and popular materials used in the concrete, and they may positively affect the properties of cementitious composites because of their superior properties. This research proposes the utilization of waste carpet fiber and palm oil fuel ash (POFA) to develop the physical, mechanical and microstructural properties of concrete. Carpet fiber of 20 mm length and six volume fractions of 0, 0.25, 0.5, 0.75, 1.0 and 1.25% were used with ordinary Portland cement (OPC). Another six mixes were made that replaced OPC with 20% POFA. The combination of carpet fiber and POFA decreased the slump values and increased the VeBe time of fresh concrete. Likewise, the addition of carpet fiber, either into OPC or POFA concrete, did not improve the compressive strength. However, the positive interaction between the carpet fiber and POFA lead to higher tensile and flexural strengths. Despite lower strength development, an increment in the post-failure compressive strength of concrete composite was observed in all mixes. A significant enhancement was also observed in impact resistance of the concrete composite containing carpet fiber, as compared to that of plain concrete. Microstructure of concrete was examined by using scanning electron microscope. It is revealed that carpet fibers act as bridges across the cracks, which improve the load-transfer capacity of the matrix. The study showed that the utilization of waste carpet fiber and POFA in the production of concrete is feasible from both technical and environmental points of view