STUDY ON THE FLEXURAL BEHAVIOUR OF REINFORCED FIBROUS CONCRETE BEAMS

In this study, behaviour of composite concrete with conventional reinforcement (i.e., steel bars) and randomly distributed metallic fiber reinforcement, and subjected to flexural loading has been examined. The objective was to investigate the effect of adding fiber in mono and hybrid form on the flexural properties of reinforced concrete. Two types of metallic fibers were used: amorphous metallic fibers (type I fibers) characterised as high performance non-slipping fibers with large specific surface area, and carbon steel hooked-end fibers (type II fibers) characterised as slipping fibers. Four types of reinforced concretes were prepared: one control (without fibers) and three fibrous. Out of three reinforced fibrous concretes, two contained single fiber and one contained fibers in hybrid form. The total volume fraction of fibers was 0.25% (20 kg/m(3)) and 0.5% (40 kg/m(3)) for single fiber and hybrid fiber concrete respectively. Three point bending test were performed according to European standards "NF EN 14651" on beam specimens of 150 x 150 mm cross section and length of 550 mm. The experimental results showed that the presence of metallic fibers appreciably reduces the crack opening and deflection and improves moment capacity of the reinforced concrete section. Moreover, as a result of positive synergetic interaction between fibers, reinforced fibrous concrete containing fibers in hybrid form exhibited more improved response at all loading stages in comparison of reinforced fibrous concrete containing fibers of one type only. Cracking and ultimate moment capacities of the beams were also determined analytically. Analytical results were found to be in good agreement with experimental results.