Fibre distribution and tensile response anisotropy in sprayed fibre reinforced concrete

Sprayed, steel fibre reinforced concrete (SSFRC) is a material that tends to present anisotropy. The shearing conditions of the spraying process induce preferential fibre orientation. Despite the extensive use of the material, no study has been found about the assessment of fibre distribution and its influence on the residual tensile strength of SSFRC. The objective of this work is to address such issue from a quantitative standpoint. An experimental program was performed with specimens extracted from different directions within a SSFRC panel. The fibre content and 3D orientation were quantified for each specimen using the inductive method. Then, the tensile behaviour was indirectly assessed for the same specimen through the Barcelona test. Results confirm the high level of anisotropy of SSFRC. The fibre orientation number parallel to the spraying direction is 3 times bigger than that found in the perpendicular direction. Similar differences were observed between the residual tensile response measured in those directions. Comparison of test results suggest that the preferential fibre orientation creates weaker planes that favours the increase of crack opening at lower load levels.