Punching shear resistance of UHPFRC

Ultra-High Performance Fibre Reinforced Concrete (UHPFRC) is a high performance cementitious material with enhanced strength in tension and compression and significantly high energy absorption in the post crack region. Its mix composition is not much dissimilar from that of normal strength concrete. The main difference is that only fine aggregates are used in order to enhance the homogeneity of the mix, while microsilica is used to improve the density of the mix thereby reducing voids and defects. A high percentage of steel fibres is used to increase the tensile strength and at the same time to provide ductility. UHPFRC has been recently introduced in applications such as bridge decks, thin slabs and for the strengthening of existing elements. Even if there are various published studies on the compressive, tensile and flexural characteristics of UHPFRC, the punching shear performance of UHPFRC without additional steel bars has not been sufficiently studied. In this paper an extensive experimental work has been conducted on UHPFRC tiles with various thicknesses and various percentages of steel fibres and tests have been conducted under a concentrated load. Using the experimental results, the punching shear characteristics of the various UHPFRC mixes have been evaluated and shear resistance values have been proposed.