Behaviour of hybrid steel fibre reinforced self compacting concrete using innovative hooked-end steel fibres under tensile stress

Abstract

The use of steel fibre hybridisation with different aspect ratios have been seen to enhance the pre and post cracking response of concrete, however the invention of new innovative macro hooked ends steel fibres with multiple hooks and increase in its linear length have been recently investigated. The results show that the new innovative macro hooked ends steel fibre with multiple hooks performed better than single hooked ends steel fibre with respect to material properties when used in self-compacting concrete. Therefore, the need to further investigate the performance of this new innovative macro (MAC) hooked ends steel fibre when combined with straight micro (MIC) steel fibre of the same aspect ratio in self-compacting concrete would be useful in the study of the stress-strain curve relationship of this composite material.A laboratory investigation on two different conditions of steel fibre hybridisation using straight MIC steel fibre (Length 13 mm and diameter 0.2 mm) with two different types of hooked ends MAC steel fibres, Single (S1) and Double (M2) hook(s) at 0.75% and 1% fibre content respectively. These are optimised values from previous experiments (laboratory tests conducted using different macro steel fibres at 0.25%, 0.5%, 0.75% and 1% fibre content). The Uniaxial direct tension test method is used. The results show that steel fibre hybridisation decreased workability due to the influence of the micro steel fibre content irrespective of the hooked ends steel fibre type. The use of Single hook (S1) macro hooked end steel fibre in steel fibre hybridisation further improved the material properties (compressive strength, tensile strength and fracture energy) when compared to the use of only macro hooked end steel fibre. However a decrease in the fracture energy is observed when Double hooks M2 macro hooked end steel fibre is used. Although positive results are seen with respect to other properties.