Análise de desempenho do concreto com adição de macrofibras sintéticas de polipropileno submetido a meio agressivo

Abstract

Numerous studies have approached the advantages of using composites in construction. Among these composites, concrete is embedded with fibers, having characteristics both changed in the fresh state and in the hardened state. The fibers in the cementitious matrix reduces crack propagation, and the most used are steel and synthetic fibers. The synthetic macrofibers have been increasingly used due to their low cost, light weight, and especially because they are inert. This work aimed to analyze performance concrete reinforced with 1% polypropylene synthetic macrofibers compared to the reference concrete subjected to the aggressive environment. From the dosage study was selected and produced with reference concrete 370 kg / m³ of cement, water / cement ratio 0.50 and plasticizer additive, which showed compression strength of 27.4 MPa, tensile strength of 7.5 MPa indirect and less than 10% absorption, which is characterized as a durable concrete may be subjected to aggression class II according to NBR 6118 (ABNT, 2014). The concrete reinforced with 1% fiber was produced with the same characteristics of the reference concrete and showed compression strength of 33.3 MPa and Traction Resistance indirect 10.8 MPa, which allows to check the effectiveness of the matrix as reinforcement macrofibers cement, crack propagation reducing and increasing the mechanical strength. The evaluation of durability was made by immersing concrete specimens with and without surface protection in a sulfuric acid solution, and parameters were analyzed: visual inspection, water absorption, weight loss and strength loss. The results showed that the concrete reinforced with polypropylene synthetic macrofibers showed better performance than the reference concrete. With regard to the two superficial protections analyzed, the polyurethane and epoxy, the epoxy protection presented better adhesion to the substrate and also more efficient by reducing the penetration of aggressive agent, thereby increasing the durability of fiber reinforced concrete.