UTILIZAÇÃO DE FIBRA DE BORRACHA DE PNEU COMO AGREGADO NA COMPOSIÇÃO DE CONCRETO

Resumo A indústria do processo de recauchutagem de pneus gera resíduos que em sua maioria têm sido descartados sem nenhum controle. Este fato contribui para aumentar a poluição ambiental e favorecer a proliferação de vetores nocivos à saúde. Visando encontrar uma aplicação para esse tipo de resíduo, neste trabalho são apresentados resultados experimentais de amostras que tiveram o intuito de avaliar o comportamento e a viabilidade do uso de fibra de borracha proveniente de pneu, adicionada em forma de agregado no concreto, com o objetivo de obter um possível material alternativo para a indústria da construção civil, contribuindo para a proteção ambiental. Prepararam-se uma dosagem de concreto sem resíduos de borracha, para servir de referência, e três diferentes dosagens contendo resíduos de borracha, com substituição do volume do agregado em 5%, 10% e 15%. Aos sete e vinte e oito dias as amostras produzidas, no total de 80 corpos de prova cilíndricos de 15 x 30 cm2, foram submetidas ao ensaio de resistência mecânica à compressão simples. Conclui-se que com a utilização das fibras de pneu, o concreto sofre uma perca de resistência em todos os casos, contudo, os traços com as porcentagens de 5% e 10%, além de um custo menor, atingiram resistência para serem utilizados em elementos não estruturais, como calçadas. Palavras-chave: Pneus inservíveis. Fibra de borracha. Agregado. Concreto. Reciclagem.   Abstract The tire retreading industry generates waste residues that has mostly been disposed of without any control. This contributes to increasing environmental pollution and promoting the proliferation of vectors that are harmful to people’s health. With the aim to find an application for this type of residue, experimental results of samples with the intention of evaluating the behavior and the feasibility of the use of rubber fiber from tires were presented throughout this article. Such samples were added as an aggregate in the concrete, with the objective of obtaining a possible alternative material for the construction industry that would contribute to environmental protection. A dosage of rubber-free concrete to serve as reference was prepared, and three different dosages containing rubber residues were prepared with 5%, 10% and 15% volume substitution of the aggregate. After the seventh and the twenty-eighth day, the samples produced, in the total of 80 cylindrical specimens of 15x30 cm², were submitted to the mechanical test of simple compression. We came to conclusion that, with the use of the tire fibers, the concrete undergoes a loss of resistance in all cases. However, the traces with the percentages of 5% and 10%, in addition to a lower cost, reached resistance that allowed it to be used in non-structural elements such as sidewalks. Keywords: Wasted tires. Rubber fiber. Aggregate. Concrete. Recycling

The Essential Oil of Eucalyptus tereticornis and its Constituents, alpha- and beta-Pinene, Show Accelerative Properties on Rat Gastrointestinal Transit

The essential oil of Eucalyptus tereticornis (EOET) has pharmacological activities but their effects on the gastrointestinal tract are yet unknown. It possesses alpha- and beta-pinene as minor constituents, isomers largely used as food or drink additives. In this work, we studied their actions on gut motility. After feeding with a liquid test meal, conscious rats received perorally EOET, alpha-, or beta-pinene, and the fractional dye retention was determined. EOET and its constituents decreased the gastric retention. In anesthetized rats, pinenes increased gastric tonus, while enhancing the meal progression in the small intestine of conscious rats. Both alpha- and beta-pinene contracted gastric strips in vitro but relaxed the duodenum. Conversely, EOET relaxed both the gastric and duodenal strips. In conclusion, EOET accelerates the gastric emptying of liquid, and part of its action is attributed to the contrasting effects induced by alpha- and beta-pinene on the gut.Instituto Nacional de Biomedicina do Semi-Arido Brasileiro (INCT-IBISAB-CNPq