Mechanical characterization of fibre reinforced concrete with steel and polyester fibre

A low volume of fibers, typically less than 2%, can be added to concrete to make Fiber Reinforced Concrete (FRC). The presence of fibers reduces the formation of cracks and their growth, thus improving the mechanical properties of the cement matrix and its structural durability. The ability of FRCs to absorb energy is one of the most important benefits of using fibers into the plain concrete. This is due to the pull-out mechanisms that should occur without fibre rupture. Many tests have been developed to characterize the energy absorption capacity of FRCs using simple loading configurations such as compression, tension and flexure. The bending test is the most widely used because it is simple to be performed and it represents a typical service condition for structural elements. This paper shows the results of an experimental study based on flexural tests of concrete reinforced with short steel and polyester fibres. Different volumes of fibers and water cement ratios were analysed in order to investigate their influence on the FRC’s toughness and workability. The experimental program involved compression tests and four point bending tests on notched specimens. Durability aspects concerning FRC structures will be also discussed. In particular, water permeability tests were performed in order to evaluate the influence of the fiber type and the fiber volume content on the permeability of the matrix.