Engineering Properties of Concrete Panels Containing Nylon Waste Fibers and Recycled Coarse Aggregates

Abstract

As a construction material, concrete has two main drawbacks: low tensile strength and a significant carbon footprint. These challenges motivate the development of techniques to improve tensile behavior and reduce environmental impact simultaneously.  Among the techniques for enhancing the tensile behavior of concrete is the addition of discrete fibers, such as steel, polypropylene, or nylon fibers, which help bridge cracks and improve post-cracking performance. In the context of mitigating carbon dioxide emissions associated with concrete production, various strategies can be employed, including the utilization of recycled materials. This study aims to employ recycled materials, specifically nylon fiber and coarse aggregate, to manufacture concrete panels. Laboratory experiments were conducted to investigate the fresh, physical, and mechanical properties associated with the utilization of nylon waste and concrete waste, specifically on the investigation of the compressive, splitting tensile, and flexural strength of the concrete panels. Additionally, fresh concrete was investigated through slump tests, while physical properties such as water absorption and mass density were examined on the hardened concrete. Fiber content was varied at 0%, 0.5%, 1%, and 1.5%, while recycled coarse aggregate replaced natural coarse aggregate at 0% and 20%. The results imply that the incorporation of fiber into concrete has an insignificant effect on compressive strength but enhances the splitting tensile strength and flexural strength, with an optimal fiber content of 1%. Meanwhile, the utilization of 20% recycled coarse aggregate (RCA) for the natural coarse aggregate (NCA) replacement offers mechanical properties comparable to those observed in concrete without recycled coarse aggregate.