Mechanical Performance of Concrete Reinforced with Discrete Steel and AR-Glass Fibres: A Comparative Study at 0.5% and 1.5% Dosage in M30 and M40 Grades

Abstract

This study presents a comparative investigation of the mechanical performance of concrete reinforced with discrete steel and alkali-resistant (AR) glass fibres at dosages of 0.5% and 1.5% in M30 and M40 grade concrete. The experimental programme evaluated cube compressive strength, split tensile strength, beam flexural strength, and thin-panel flexural strength to assess the influence of fibre type, dosage, and concrete grade. Eight concrete series were prepared using the two fibre types and tested at specified curing ages, with compressive strength evaluated at 7 and 28 days and the remaining mechanical properties evaluated at 28 days. The results indicate that increasing fibre dosage from 0.5% to 1.5% generally improved the mechanical performance of both fibre-reinforced concrete systems, with a minor exception in the split tensile strength of M30 concrete containing steel fibre. Steel fibre exhibited superior performance to AR-glass fibre in almost all test configurations, particularly in tension- and flexure-dominated tests. The M40 concrete containing 1.5% steel fibre recorded the highest overall performance, achieving 49.78 MPa compressive strength, 5.35 MPa split tensile strength, 4.95 MPa beam flexural strength, and 4.81 MPa panel flexural strength. Steel fibre also demonstrated improved post-cracking behaviour, as the tested beams remained connected after cracking, whereas AR-glass fibre beams separated at failure. The findings demonstrate that discrete steel fibre is more effective for maximising mechanical strength, while AR-glass fibre remains a viable corrosion-resistant alternative. The study also highlights the importance of reinforcement geometry when interpreting the performance of AR-glass reinforcement and provides a basis for further investigation of fibre dosage and hybrid reinforcement systems.