Navegando por Autor "PINTO, Renata Godinho"
Agora exibindo 1 - 2 de 2
- Resultados por página
- Opções de Ordenação
Item Acesso aberto (Open Access) Compósitos cimentícios reforçados com fibras de curauá (Ananas erectifolius) impregnadas com sílica ativa(Universidade Federal do Pará, 2019-02-01) PINTO, Renata Godinho; PICANÇO, Marcelo de Souza; http://lattes.cnpq.br/4535052395600357Vegetal fibers are an alternative for reinforcement in cementitious mortars, unlike the synthetic fibers, they are renewable, biodegradable and low cost. The great limitation of these composites concerns the low durability of the fibers inserted in the cementitious matrix. Therefore, the present research aim to analyze the properties of reinforced mortars with curaua fibers previously impregnated with silica fume. The mix design ratio of the composites was determined with a pilot study. The composites were prepared with mix design ratio 1:3:0.61 and with addition of 2% fibers with 25 mm length. Six families were molded using CP-IV cement and CP-II E. The properties of the composites were verified at 28 days and after natural aging at 180 and 270 days. The characteristics of the curaua fiber used were: density of 1.33 g/cm³, tensile strength of 422.89 MPa and modulus of elasticity of 28.83 GPa. For compressive strength, the composites fibers previous treatment provided a better result than that obtained for mortars with natural fibers. For the tensile strength, inclusion of fibers provided the desired reinforcement improving this property in 45 %. The modulus of elasticity indicated that the addition of the fibers reduced the stiffness of the material. For flexural strength the composite AFCS:IV showed a 57.95 % increase compared to the reference, but it was identified with the natural aging the decrease of the resistance for composites with untreated fibers. The proposed treatment was effective to preserve the toughness of the composites after natural aging. Due to the composites X-ray diffraction, it was verified that the previous treatment of the fibers was effective in limiting the formation of the portlandite in the matrix. This corroborates with micrographs of the mortars, where degradation signals were identified in composites with untreated fibers, while the previously treated fibers remained intact even after natural aging. Thus, it can be considered that the impregnation of the fibers with silica fume improved the properties of the composites and increased the durability of the curaua fibers.Item Acesso aberto (Open Access) Corrosão em estacas metálicas de torres de energia elétrica(Rede Latino-Americana de Materiais, 2019-05) VILHENA, Alexandre Evangelista Rodrigues; PINTO, Renata Godinho; COSTA, Rafaela Reis da; PICANÇO, Marcelo de Souza; MACÊDO, Alcebíades NegrãoIn order to maintain the quality and continuity of the power supply it is essential to monitor the integrity of the structure of the transmission towers usually executed in steel. This study evaluated soil corrosivity in the Amazon region in the Vila do Conde-Tucuruí stretch, state of Pará. The resistivity, potential soil structure, redox potential, pH, chloride, sulphate and sulfate concentration, besides the Steinrath index and the quantification of the soil corrosivity through the installation of test specimens in the studied soil. The data were collected in the dry and rainy period while the specimens were removed after 12 months of exposure. The soils of the region presented resistivity higher than 20 kΩ.cm, characterizing as few corrosives; the redox potential of 100 to 300 mV indicated mild to moderately corrosive soils; the potential soil structure remained in the range of -0.4 to -0.7 V/ECS being within the range considered normal; the Steinrath index classified the soils into little corrosive to non-corrosive and the corrosion rates of the test specimens indicated high corrosion at 3 meters depth. Based on the results of each evaluation method used it can be verified that the soil corrosivity increases with the depth, besides being favorable to the attack of microbiological corrosion.