The effect of fibre orientation on the uniaxial tensile response of UHPFRC: Experimental evaluation and analytical modelling

Abstract

The tensile strength of Ultra-High Performance Fibre-Reinforced cementitious Composites (UHPFRC) depends primarily on the properties of the matrix and fibre's length and geometry, but can also vary significantly according to the fibre orientation. In this study an experimental campaign is developed involving 22 uniaxial tensile tests on UHPFRC specimens with varying fibre content (1.5% and 3% in volume) and fibre orientation profiles (well oriented, randomly oriented and poorly oriented). The different fibre orientation profiles were obtained using a magnetic setup for orienting the fibres along a pre-defined direction during casting. The fibre orientation profiles were quantitatively analysed using image analysis algorithms, allowing the determination of fibre orientation angle distributions and other scalar fibre orientation indicators. The results of the uniaxial tensile tests clearly evidence the effect of fibre orientation and fibre content not only on the tensile strength, but also on the development of the hardening branch that is typical of this type of cementitious composites. A methodology is proposed for estimating the parameters of a simple analytical model providing the tensile strength of the composite. It is shown that the full tensile response can also be reasonably predicted using a meso-mechanical model of the composite. (c) Springer International Publishing AG 2018.