Reforço de compósitos cimentícios aditivados com fibras de eucalipto e de pinus, puras e com TEOS.

Abstract

The advancement of research on the properties of vegetable fibers expanded their applications and assisted in getting new products. The vegetable fibers are lowdensity compared to other fibers, non-abrasive, porous, viscoelastic, biodegradable, of easily surface treatment and renewable, started to be used as reinforcement in many kinds of composite materials. In the cement matrix composites its insertion favored the light weight and improved the mechanical properties of the products. The study aims to evaluate the reinforcement cementitious composites additiveswith fibers of eucalyptus and pine, pure and treated with TEOS (tetraethylorthosilicate - organically modified silica), from the knowledge of their physical, mechanical and microstructural properties. For the development of this work were obtained commercially fibers pine, eucalyptus and high early resistance cement (CPV). The fibers were characterized for their water absorption, pure and treated with TEOS and morphology (length and width) by optical microscopy. In order to obtain the composite, cement composites were prepared with addition of 2, 5 and 10% for fibers of eucalyptus and pine, humid, dry and with TEOS. The composites were characterized physically and mechanically by testing water absorption, porosity and bending resistance at three points. For the composites with best mechanical performance it was obtained images of the interface, from the electronic microscopy scanning technique and analyzed the chemical composition, employing the technique of energy dispersive spectroscopy (EDS). The use of TEOS provided to reduce the rate of water absorption of eucalyptus fibers and the reduction of the porosity in the composite. The preparation of the fibers influence the final reinforcement of the composite. The morphology of eucalyptus fiber and low porosity obtained on TEOS composites with fibers account for the higher mechanical resistance values obtained. Compared to a pure mass of cement, cement composites and eucalyptus fibers exhibit higher reinforcement to the cement matrix to the cement and fibers of pine. The composites with highest reinforcements were made with 2% fiber, pure and with TEOS. Regardless of the type of fiber, increasing the amount of fiber results in a loss of mechanical resistance of the composite. The composite with 2% eucalyptus fiber with TEOS was the one that got the biggest boost with gains of 30.96% on the value of bending resistance at three points. Microstructural analysis showed that there was interaction of the fibers of eucalyptus and pine with the cement paste.