Estudo da influência de diferentes tratamentos (fibra/matriz) nas propriedades mecânicas de compósitos cimentícios reforçados com fibra de malva

Abstract

Since ancient times it has been known the use range of natural fibers and other organic and inorganic materials such as reinforcing agent in matrix to improve their mechanical properties. The vegetable fibers have numerous advantages for use in composites such as low cost, low density and abrasion, are nontoxic, biodegradable, abundant in nature and other factors. From this, it was decided to use the mauve fiber (Urena lobata Linn), widespread in the Amazon region and sold in the local market, as a reinforcing agent in cement composites. This study aimed to develop laminar cement composites with long alignments of mauve fibers, consisting of 6% by volume of fibers dispersed in 5 longitudinal layers, to obtain a laminar plate. It was proposed two kinds of treatment to the composite: impregnating the fibers by immersion coating based on acrylic copolymer emulsion in order to decrease hydrophilicity and matrix treating with comminuted ceramic waste in 50% partial replacement of the Portland cement to provide calcium hydroxide decrease and improving the mechanical strength of the composite protecting the vegetable filler. The composites were characterized by direct tensile, 4 points bending, optical microstructural analysis and scanning electron. The fibers were characterized by thermogravimetry and morphological analysis using optical and scanning microscopy in order to evaluate varnish treatment. The results of electron microscopy showed no improvement interfacial between fiber and matrix after treatment. Moreover, the mechanical tests showed that the composite with the partial substitution of ceramic waste have presented the same or superior results when compared to the Portland cement matrix, both for the reinforcement with the treated fibers and the untreated, leading to consider the mauve fiber relevance as a promising reinforcement agent for high strength composites.