Experimental study on shear strength of composite slab with steel fibre reinforced concrete topping

Abstract

The conventional method of concrete composite slab construction uses steel fabric (SFA) as a secondary reinforcement in concrete topping. Nevertheless, there are various shortcomings of which most of industrial practitioners take it for granted. These include improper SFA installation that may cause a reduction to the concrete cover and longer time is needed to fix the adjacent meshes, as stronger connection is needed between the overlaps. In order to reduce problems associated with SFA, this study utilised steel fibre reinforced concrete (SFRC) in concrete topping to replace SFA as a secondary reinforcement. It is to be investigated about the shear strength of composite slab with a steel fibre of different proportion and length. Five concrete composite slabs were prepared, in which each varied in terms of steel fibre parameters, i.e. fibre aspect ratio (L/D = 80 and L/D = 60) and fibre volume fraction (Vf = 0.75% and Vf = 1.00%). The control specimen was also prepared for comparison purposes, where the concrete topping was reinforced with SFA. All composite slab specimens were tested for 28 days after casting and subjected to shear load. Each slab specimen undergone two different experimental setups by considering the left and right section. The test results have shown that SFRC composite slab can sustain a higher shear load as compared to the control. This improvement is in the range of 14% to 17% and 8% to 15% for SF33 and SF60, respectively. In addition, the study has also found that steel fibre with smaller aspect ratio in the concrete topping can sustain higher ultimate shear capacity as compared to the larger aspect ratio. To that, this research proved the benefits of SFRC in concrete topping in which it can reduce the problems associated with the use of SFA.