Concreto reforçado com macrofibras sintéticas de polipropileno para pisos industriais aplicados na região metropolitana de Belém-PA

Abstract

The present study focuses on developing Portland cement concrete for industrial floors with a hybrid addition of polypropylene synthetic macrofibers (Duristeel FF54 and BarChip MQ58), added at 0.5% and 1.0% by concrete volume. In the 0.5% dosage, 0.25% of each type of fiber was used, while in the 1.0% dosage, 0.5% of each fiber was added. The research involves conducting experimental dosing using the IPT/EPUSP method to obtain the reference mix of concrete (without fibers) with a compressive strength of 40 MPa; and the characterization of the physical and mechanical properties of the concrete with and without fiber addition, through tests such as slump, axial compressive strength, flexural tensile strength, modulus of elasticity, specific gravity, water absorption, void ratio, and morphological analysis of the fracture surface. The experimental dosage of concrete using the IPT/EPUSP Method generated a customized diagram for the Metropolitan Region of Belém-PA, optimizing performance and quality. The results of concrete in the fresh state indicated that the addition of fibers reduces slump as its content increases, making it necessary to use a water-reducing additive to maintain this parameter. In the hardened state, the incorporation of 0.5% fibers increased the axial compressive strength at 28 days, while 1.0% resulted in a reduction compared to the reference concrete. The increase in fiber content also improved the modulus of elasticity and reduced the void ratio, water absorption and specific gravity. In the flexural tensile tests, the polymeric macrofibers did not change the maximum strength, but improved the post-peak behavior, providing greater ductility and residual strength, with better performance at 1.0% of fibers. Microstructural analysis revealed good adhesion between the fiber and the matrix, with interception of cracks by the fibers. The addition of fibers changed the failure mode of the concrete, from predominantly longitudinal cracks to inclined and more evenly distributed cracks, promoting a better redistribution of internal stresses and reducing the severity of cracks. The results confirmed that concrete reinforced with polypropylene fibers is effective for industrial floors, especially due to the improvement in post-cracking resistance, which is crucial for environments with high mechanical demands.