Three-versus four-point bending tests: an experimental investigation on Steel Fiber-Reinforced Concrete

The identification of mechanical and fracture properties of Steel Fiber-Reinforced Concrete (SFRC) is necessary to investigate its influence on structural behavior. Of course, it is advisable to use standard specimens and to make reference to standard recommendations to measure and evaluate SFRC properties. In the past, different test procedures and parameters have been proposed to characterize the post-cracking behavior in tension and the toughness properties. As a result, some topics were highly debated and various proposals were made by a number of scientific and technical committees. Recently, RILEM has proposed a 3-point bending-test procedure, while the Italian Institute for Standards – UNI is suggesting a 4-point bending-test procedure. In this paper, the results obtained by means of 3-point bending tests (according to RILEM TC 162-TDF, 2002), and those obtained by means of 4-point bending tests (according to UNI 11039, 2003) are critically examined by testing notched SFRC prisms. The objectives of this project on SFRC are: (a) to analyse and compare the experimental results in terms of peak load, post-peak behavior and residual strength; and (b) to assess fiber contribution in Mode I - fracture with respect to plain concrete.