Effect of hybrid fibres on the static load performance of concrete beams

Fibre-reinforced concrete (FRC) has been increasingly used in construction for several decades to reduce crack growth by incorporating one or two types of fibre in reinforced concrete elements under the static load. This paper intends to investigate experimentally how hybrid fibre systems (micro and macro polypropylene fibres and steel fibres) can enhance the performance of RC beams subjected to static loading by restricting the development of micro-cracks and macro-cracks. The test programme consisted of testing six full-scale simply supported beams. The main parameters were fibres’ addition (i.e. steel and polypropylene fibres) and volume fraction (i.e. 1 and 1.5% for steel and hybrid fibre system (1% steel, 0.1% micro, and 0.4% macro polypropylene fibres)). From the test data analysis, it was found that the hybrid fibre system decreased the deflection, reduced the strain in the steel reinforcement bars, and reduced the crack width. The splitting tensile strength and compressive strength of the hybrid fibre-reinforced concrete was greater than that of the single fibre-reinforced concrete. The addition of more than two types of fibres illustrates a pronounced beneficial hybrid effect.