INFLUENCE OF GLASS AND POLYPROPYLENE FIBERS ON THE RESIDUAL TENSILE STRENGTHS OF HYBRID FIBER REINFORCED CONCRETE

This study aims to investigates the post-cracking behaviour of glass fiber (GF) and polypropylene (PP) reinforced concrete and the effect of hybrid fibre combinations on the mechanical properties of the composite. The effect of these dosages on Limit of Proportionality (LOP) and Residual Strength (fr), which were determined through bending Tensile Tests, had been used to analytically study the data obtained from six different concrete mixtures with different contents of fiber. Scanning Electron Microscopy (SEM) analyses were conducted to understand the fiber-matrix interface and identify potential fiber detachment. The M25-75 hybrid mix (25% GF and 75% PP fibers) exhibited the best post-cracking performance, with an LOP of 3.87 MPa and a Residual Strength of 1.80 MPa at 4% strain (fr4). In contrast, the M75-25 mix (75% GF and 25% PP fibers) showed the best performance in the elastic phase, with an LOP of 4.33 MPa and a lower Residual Strength of 1.22 MPa at 4% strain. These results suggest that while GF fibers enhance the LOP, PP fibers improve Residual Strength. Their hybridization achieves an equilibrium between Initial Strength and Ductility, therefore, hybrid concrete appears to be a viable alternative in structural application.