The present work is part of an innovation research project aiming to develop artificial stone from industrial wastes. In principle, the project goal is to fabricate artificial stones with improved characteristics to be used as plates for housing and road construction. In this work, the specific industrial residue was an electrostatically precipitated powder obtained from the initial sintering stage of an integrated steelmaking plant. Plates were produce by vacuum vibro-compression of epoxy resin mixed with 80 and 85 wt% of this specific residue. After curing, the plates were characterized for physical parameters and mechanical properties. The microstructural aspect of the finishing surface was analyzed for both novel artificial stones by scanning electron microscopy. The results indicated that the 80% residue incorporated artificial stone is superior to the 85% residue incorporated and markedly stronger than a commercial artificial stone, incorporated with granite residue, with comparable density and water absorption. These characteristics favor the technical substitution of the presently investigated artificial for the commercial stone. In particular, based on wear tests, the residue incorporated artificial stone would be restricted to application as pavement in medium traffic roads.

ResumoRealizou-se um estudo da variação com a temperatura dos parâmetros dinâmico-mecânicos de compósitos com matriz poliéster incorporada com fibras de coco. Diferentes percentagens em peso de fibras de coco, até 40%, foram misturadas com resina poliéster ortoftálica e, após prensagem, curada por 24 horas à temperatura ambiente. Ensaios dinâmico-mecânicos (DMA) foram realizados para se obter os módulos de armazenamento e perda, bem como a tangente delta para cada tipo de compósito com diferentes quantidades de fibra de coco. Os resultados desses parâmetros revelam que a incorporação de fibra de coco diminui a rigidez viscoelástica do compósito com matriz poliéster. Esta redução na rigidez está associada à baixa tensão interfacial, o que dificulta a transferência de esforços mecânicos da matriz para a fibra. Ocorrem também modificações na temperatura de transição vítrea e no pico α de relaxação com a incorporação de fibras de coco. Em particular, o amortecimento do compósito que está relacionado ao valor da tangente delta, diminui a quantidade de fibra incorporada pelo fato de somente parte da tensão aplicada deformar a interface fibra/matriz. Palavras-chave: Fibra vegetal; Compósitos; Matriz poliéster; Comportamento; Temperatura de transição. EFFECT OF COIR FIBER INCORPORATION IN DYNAMIC MECHANIC BEHAVIOR OF POLYESTER-MATRIX COMPOSITES AbstractA study on the temperature variation of the dynamic-mechanical parameters of polyester matrix composites incorporated with continuous coir fibers was carried out. Different weight percentages, up to 40 wt.% of coir fibers, were mixed with orthophtalic polyester resin and, after press-molding, cured for 24 hours at room temperature. Dynamicmechanical, DMA, tests were conducted to obtain the storage modulus and the loss modulus as well as the tangent delta for each type of composite with different amounts of coir fibers. The DMA results revealed that the incorporation of coir fiber decreases the viscoelastic stiffness of the composite with polyester matrix. This reduction in stiffness is associated with a low interfacial shear stress, which makes it difficult for the mechanical load transfer from the matrix to the fiber. Modifications in the glass transition temperature and in the α relaxation peak also occurred with the amount of incorporated coir fiber. In particular, the damping response of the composite, associated with the value of the tangent delta, decreases with the amount of incorporated fiber owing to the fact that only part of the applied stress was used to deform the fiber/matrix interface.