Estudo da utilização de tratamento polimérico com sílica de casca de arroz no comportamento à tração direta e aderência da fibra de sisal em compósitos cimentícios

Abstract

Due to the evolution of cementitious materials, the incorporation of innovative technologies becomes of paramount importance when it comes to constructive processes. Considering that cement-based materials have many advantages, however, they have restrictions when they are requested by tensile stresses, exhibiting fragile behavior and low tenacity, the option to use vegetable fibers as reinforcement is considered beneficial, as they demand less energy for extraction and tend to improve the mechanical properties of the composite. However, to modify the characteristics of natural fibers through the application of some type of treatment can provide an increase in mechanical strength and increase the fiber-matrix anchoring capacity. In this way, seeking the incorporation of natural and renewable materials, in order to provide better mechanical properties to the cementitious composites, this work aims to perform the application of treatment using expanded polystyrene and Rice Husk Silica in sisal fibers in order to evaluate the absorption capacity and analysis of the surface microstructure of the sisal fiber, verifying the effectiveness of the treatment in the longitudinal uniformization of fibers. This study also analyzes the effect of the polymer treatment with Rice Husk Silica on the direct tensile strength of natural and treated sisal fibers with 50 mm fiber length, as well as their influence on the fiber-matrix adhesion capacity through pullout tests using length of embebiment of 50 mm fiber for the control ages of 7 and 28 days. In the analysis of the results it was observed that the proposed treatment reduced the water absorption index of the sisal fibers, causing greater homogeneity in the data obtained for tensile strength, but did not provide significant alterations to the strength of fiber rupture. For the analysis of microstructure it is observed that the sealing of the fiber occurred through the treatment, also occurring points of agglutination along the same. Regarding the adherence behavior, it was observed that the proposed treatment impaired the fiber-matrix interaction for both control ages analyzed.