Self-compacting concrete with blended short and long fibres: experimental investigation on the role of fibre blend proportion

Abstract

In this paper, micro and macro steel fibres were used to understand the influences of blended fibre addition on the fresh and hardened properties of self-compacting concrete (SCC). Five mixtures containing micro and macro steel fibres were prepared in different combinations and in each mixture, the sum of the steel fibre content was kept constant as 1%. To measure the workability of fibre-reinforced self-compacting concrete (FR-SCC), slump-flow diameter, t 500 and J-ring tests were conducted. The results indicated that when the micro steel fibre ratio became more than 0.25%, the fresh properties of SCC were affected negatively. To determine the hardened properties of FR-SCC mixtures, compressive, splitting tensile and flexural tensile strength tests were performed and also ultrasonic pulse velocity (UPV) of the specimens was measured. The micro steel fibre inclusion had positive effect on compressive strength while it caused a reduction in splitting tensile and flexural tensile strength. With regard to the crack formation, in the mixtures having higher content of macro steel fibre, multiple crack behaviour was observed. Moreover, it was revealed from the results that the mixtures exhibited deflection-hardening response in the case of inclusion higher amount of macro steel fibre.