Influence of fibre orientation on the tensile behaviour of ultra-high performance fibre reinforced cementitious composites

The main objective of this study is to quantify the effect of fibre orientation on the tensile behaviour of Ultra-High Performance Fibre-Reinforced Cementitious Composites (UHPFRC). A strategy to align the steel fibres within the matrix based on the activation of an external magnetic field while casting is adopted to achieve a wide range of fibre orientation profiles. The uniaxial tensile test is used for determining the tensile stress-elongation curves of 22 specimens and the quantitative evaluation of the fibre density and orientation characteristics is performed resorting to an image analysis technique. Based on the obtained results it was possible to validate an analytical formulation for determining the tensile strength of UHPFRC and to quantify the involved parameters. It is also shown that length of the hardening branch of the tensile stress-elongation curve is also very well correlated with the same parameters used in the determination of the tensile strength.