Effect of recycled waste nylon granules and treated sisal fiber on the physical, mechanical, and durability properties of sustainable concrete

Waste nylon is a highly polluting synthetic material and a group of polymers. Previous studies have investigated recycled nylon granules and sisal fibre separately, while others explored the combined use of waste water bottle as a fibre and treated sisal fibre in concrete. However, it is novel to use recycled nylon granules as fine aggregate with and without treated sisal fibre in concrete mixture. A comprehensive laboratory program was conducted, including workability, density, compressive strength, splitting tensile strength, water absorption, crack width, elevated temperature tests up to 400°C, and microstructural characterization using scanning electron microscopy for concrete containing different recycled nylon granule doses and treated sisal fibers. The results show that the use of recycled nylon granules and treated sisal fibers increased the workability, compressive and splitting tensile strength, and significantly reduced the fresh and dry density, crack width, and water absorption of concrete. The use of recycled nylon granules and treated sisal fibers at GF5 increased the compressive strength by 25.62% and 6.61%, respectively, at 28 and 56 days, and 26.67% splitting tensile strength at 28 days compared to the control mixture. However, the mass of concrete sample G5 lost at 400 ° C was 64.23% lower than that of the concrete sample with recycled nylon granules at an elevated temperature of 150°C. In general, the combined use of recycled nylon granules and treated sisal fibers shows an effective approach to enhance the physical, mechanical, durability, and microstructural properties of concrete, even when exposed to elevated temperatures of 200°C. Moreover, this practice contributes to reducing environmental pollution caused by plastic waste and promotes the use of biodegradable materials for sustainable concrete production.