A multi-criteria evaluation and optimization of sustainable fiber-reinforced concrete developed with nylon waste fibers and micro-silica

<title>Abstract</title> Nylon waste fibers (NWF) similar to new nylon fibers possess high tensile strength and toughness, hence, they can be used as an eco-friendly discrete reinforcement in high-strength concrete (HSC). This study aimed to analyze the mechanical and permeability characteristics and life cycle impact of HSC with varying amounts of NWF and micro-silica (MS). The results proved that NWF was highly beneficial to the tensile and flexural strength of HSC. At the combined addition of 0.5% NWF and 7.5% MS, splitting-tensile and flexural strength of HSC experienced net improvements of 49% and 55%, respectively. Lower doses of NWF were beneficial to the durability of HSC. However, 1% NWF was harmful to the durability of concrete. For the optimum mechanical performance of HSC, 0.5% NWF can be used with 7.5% MS. The use of MS also nullified the negative effect of the high volume of NWF on the penetration resistance of HSC.