A Review on Fly Ash and Coconut Shell Based Steel Fiber Reinforced Concrete for Sustainable Construction

The construction industry is under increasing pressure to reduce its environmental footprint while maintaining structural performance and durability. One promising approach is the development of sustainable concrete through the partial replacement of cement and natural aggregates with industrial and agricultural by-products, coupled with fiber reinforcement. This review paper critically examines existing research on the use of fly ash as a partial replacement of cement and coconut shell as a partial replacement of coarse aggregate in Steel Fiber Reinforced Concrete (SFRC). The paper synthesizes findings related to fresh properties, mechanical performance, durability characteristics, and sustainability benefits of fly ash–coconut shell–SFRC systems. Particular attention is given to the role of steel fibers in mitigating strength loss, enhancing ductility, and improving crack resistance. The review identifies optimal replacement ranges, discusses key challenges such as workability and water absorption, and highlights research gaps for future investigation. The study concludes that fly ash–coconut shell–SFRC represents a viable and eco-friendly alternative to conventional concrete, with strong potential for structural and non-structural applications.