Dynamic Tensile Properties of Steel Fiber Reinforced Concrete R. Chen 1* , Y Liu 2 , X. Guo 2 , K. Xia 3 , and F. Lu 1 1. College of Science, National University of Defense Technology, 410073 Changsha, P.R. China 2. National Key Laboratory of Explosion Science and Technology, Beijing Institute of Technology, 100081 Beijing, P.R. China 3. Department of Civil Engineering, University of Toronto, Toronto, Ontario, Canada M5S 1A4 ABSTRACT: This paper presents experimental results on three kinds of concretes, plain concrete (PC), 1.5% and 3% steel fiber reinforced concrete (SFRC), subjected to dynamic tensile loading. The cylinder splitting (Brazilian disc) specimens are loaded by a modified Split Hopkinson Pressure Bar (SHPB) with various loading rates (100~500 GPa/s). From the experiments it is found that there is a significant enhancement in tensile strength with increasing loading rates. Crack gauges mounted on the specimen showed that the average fracture velocity of 3% SFRC during the test is 730 m/s whereas that of PC is 790 m/s. Both the tensile stress history and the recovered specimen have demonstrated that SFRC has superior resistance to crack initiation and crack propagation as compared with PC. Keywords: Steel fiber reinforced concrete (SFRC); Brazilian Disc; SHPB; Fracture velocity INTRODUCTION Fiber reinforcement is one of the most important modification methods to alter the brittle nature of plain concrete (PC). The use of steel fiber reinforced concrete (SFRC) has been continuously increasing during the past decades because of its enhancement of material performance in toughness and crack control [1]. With the addition of steel fibers, SFRC shows an enormous increase in strength, toughness, and ductility from static mechanical tests [2]. As a result, SFRC has been widely used in many civil engineering structures. However due to its limitations in the flexibility and resistance to shrinkage cracking, it has been rarely used in bridge pavement. The success of SFRC in structural engineering has encouraged the development of newer high performance materials for critical infrastructures subjected to extreme loadings. Among these loading cases, intense dynamic loading is a unique one because of the worldwide increase of terrorist attacks against civilian targets. It is thus critical to better understand the impact resistance of SFRC and methods to enhance its performance under such loadings [3]. Over the past few years, significant progress has been made in the characterization of dynamic properties of SFRC [4-7]. However, the tensile strength has rarely been measured. It is thus the objective of this work to quantify the dynamics tensile behaviour of PC and SFRC. We use the Brazilian disc sample and apply the dynamic load with a modified split Hopkinson pressure bar (SHPB) system. The influence of the loading rate and fiber volume fraction on dynamic tensile strength is studied. To illustrate the tensile failure process, crack velocities are monitored. EXPERIMENT Sample preparation and geometry The concrete matrixes were designed for accommodating the volume fraction (V f ) of 0, 1.5% and 3% of steel fibers. The following materials were used in the fabrication of SFRC specimens: tap water, cement, steel fiber, standard sand, Silica fume, fly ash, water reducer and steel fiber. Tables 1 and 2 present the properties of raw material and the compositions of each component. * Corresponding author. Tel: +8673184573276; fax: +8673184573297. E-mail address:R_Chen@nudt.edu.cn T. Proulx (ed.), Dynamic Behavior of Materials, Volume 1, Conference Proceedings of the Society for Experimental Mechanics Series 99, 37 DOI 10.1007/978-1-4614-0216-9_5, © The Society for Experimental Mechanics, Inc. 2011