Characterization of eco-friendly steel fiber-reinforced concrete containing waste coconut shell as coarse aggregates and fly ash as partial cement replacement

This study investigates the effect of steel fiber addition into eco-concrete made with fly ash, an industrial by product, as partial cement replacement material, and coconut shell, an agricultural waste, as coarse aggregates, on the mechanical properties. Two different mixes were developed, one with coconut shell only as coarse aggregates, and the other with both conventional aggregates and coconut shell as coarse aggregates. The cement content was replaced with class F fly ash at 10% by weight. Steel fibers of 0.25, 0.5, 0.75, and 1.0% by volume of concrete were used. The properties investigated were slump, density, ultrasonic pulse velocity, compressive strength, split tensile strength, flexural strength, and modulus of elasticity (MOE). The findings indicated that the addition of steel fibers resulted in a reduced slump and slightly increased density in the fresh concrete mixes. Meanwhile, enhancements of up to 39% compressive strength and 17% MOE were also obtained. A substantial improvement in split tensile strength and flexural strength were also observed. Steel fiber addition also significantly reduced the brittleness of concrete containing coconut shell. The outcomes of the experiment revealed that steel fiber addition yielded a positive result on the mechanical properties of coconut shell concrete.