Characterisation proposal of direct shear strength of steel fibre-reinforced concrete

This study proposes the direct pure shear characterisation of steel fibre-reinforced concrete specimens with two grooved shear planes. Initially, the crimped fibre type was used with a rate varying between (0.0 %, 0.5 %, 1.0 %, and 1.5%), a concrete compressive strength of 35 MPa, a maximum aggregate size of 9.5 mm, and eight specimens subjected to the direct shear test. The results showed a significant gain in shear strength with increased fibre consumption, 90% at a rate of 1.5%. Based on these observations, three analytical expressions were formulated to compute the shear stress. The validation of the models was applied to a group of fifteen blocks of the same smaller size geometry and had as additional variables the hooked-end fibre, the concrete compressive strength of 25 MPa, the type and the maximum size of the coarse aggregate (19 mm and 25 mm). Crimped fibre confirmed good performance compared to the hooked-end, with a strength gain of around 100% at a rate of 1.5% with the maximum coarse aggregate particle size of 25 mm, showing variability between 2 and 7% in the proposed analytical models.