Influence of local fiber distribution on tensile behavior of strain hardening UHPFRC using NDT and DIC

This paper introduces the uniformity factor mu(2) for considering the local fiber distribution within elements made with Ultra-High Performance Fiber Reinforced Cementitious Composites (UHPFRC). The influence of mu(2) on the strain-hardening response of UHPFRC under uniaxial tension is investigated quantitatively by means of experimental campaign and mechanical analysis. The uniaxial direct tensile test (DTT) was carried out on dumbbell specimens, extracted from a slab, to characterize the tensile behavior of UHPFRC using digital image correlation (DIC) system. Before DTT, actual fiber distribution of each specimen was measured by non-destructive test (NDT) method. Based on the present results and available literature, it is concluded that mu(2) plays a significant role in tensile strain-hardening response, especially hardening strain epsilon(Utu) and matrix discontinuities energy g(Uf), of UHPFRC. The average mu(2) value for a given UHPFRC structural element is proposed to be applied for scaling the representative tensile response to intended applications.