Estudo experimental de concretos híbridos reforçados com fibra vidro e polipropileno armados com GFRP

Abstract

This study investigated the performance of concrete reinforced with hybrid alkali-resistant glass fibers (GF) and polypropylene (PP) in two experimental phases. In the first stage, the behavior of different CRF mixtures was evaluated in flexural and compressive tensile strength tests. The results demonstrated that traits T75-25 and T50-50 met all the normative requirements, with LOPs of 4.33 MPa and 4.05 MPa, respectively, and residual strengths higher than the minimum values required. The T75-25 mixture was selected for the second phase because it combined high LOP and good post-cracking performance, demonstrating the synergy between glass and polypropylene fibers. In the second phase, four-point bending tests were carried out on reinforced beams using the T75-25 mixture from the first phase. Three different compositions were compared: reference with steel reinforcement (V11-AR and V12-AR), super-reinforced with GFRP (V21-GS and V22-GS) and with altered moment of inertia (V31-GI and V32-GI). The beams super-reinforced with GFRP reached maximum rupture strengths up to 80% higher than the steel beams, but showed greater displacements. However, the beams with an altered moment of inertia had a behavior closer to the steel beams, with reduced displacements and a similar maximum rupture force. The presence of hybrid fibers was essential for controlling cracks, delaying their initial formation and preventing catastrophic ruin, especially in the GFRP beams. The results highlight the role of glass fibers in increasing initial crack resistance and the effect of polypropylene fibers on post-cracking structural integrity. The combined use of CRF and GFRP demonstrates potential for improving the performance of structural elements, combining strength and deformation control, especially in aggressive environments.