Utilização de fibras de polipropileno como fator de minimização da desagregação do concreto ocasionado pelas altas temperaturas

Abstract

Widely, concrete is the most applied building material in the world, due to several factors. Among its properties, it is possible to highlight its good performance at high temperatures, characterized by its low thermal diffusivity and non-combustibility. However, although concrete has good resistance and stability against fire, with increasing temperature its mechanical strength decreases over time. Therefore, this work aims to study the influence of high temperatures in conventional concrete, as well as the sudden cooling of the concrete, verifying the residual mechanical properties and the durability of the samples, with and without the addition of polypropylene fibers. For this, tests were performed on cylindrical specimens. Using a concrete with a characteristic strength of 30 MPa, varying the polypropylene fiber content, between 1, 2 and 3 kg/m³, using different gradients of temperature, environment, 250ºC, 500ºC and 750ºC. Afterwards, a sudden thermal shock was applied to the samples using the method of immersion of the specimens in water. Thus, throughout this research it was possible to verify that polypropylene fibers improve the properties of concrete at ambient temperatures and at 250°C. At higher temperatures, it gives approximate results with the reference trace. Therefore, in general, the ideal traits, in order to improve and minimize concrete degradation at high temperatures, were those without fiber and with 1 kg/m³ of polypropylene fiber, presenting more regular and satisfactory results, leaving it to the engineer civil choose or not to use polypropylene microfiber in his work, since in both cases the results were similar. [resumo fornecido pelo autor]