Combined influence of waste steel fibre and fly ash on rheological and mechanical performance of fibre-reinforced concrete

ABSTRACT This study aims to investigate the combined influence of varying concentration of waste steel fibre and fly ash on rheological and mechanical performance of fibre-reinforced concrete (FRC). Cement was substituted partially by fly ash at concentration of 5%, 10% and 20% by weight basis and waste steel fibre was incorporated as 1.5% and 3% in volume basis of concrete. Rheological tests of concrete, including slump, density, compacting factor, K-slump, and Kelly ball penetration were evaluated for the fresh state. Mechanical performances of concrete, including compressive, splitting tensile and flexural strength were determined at 7 and 28 days. Test results exhibited that fly ash enhanced the workability of all rheological tests; however, waste steel fibre reduced the workability and increased the density of fresh concrete. Substantial enhancement in compressive, splitting tensile and flexural strength was found for fly ash and waste steel FRC mixes than the control one. The optimum results of mechanical performance were achieved for mixture with concentration of 10% fly ash and 3% waste steel fibre among all mixes. Adding waste steel fibre with fly ash in concrete provided more pronounced mechanical performance at higher fibre concentration along with the minimisation of disposal problems and environmental damages.