RESUMOEste estudo trata da análise das propriedades mecânicas do concreto, elaborado a partir da substituição de parte do agregado miúdo por borracha de pneu triturado. Foram realizados testes experimentais em corpos de prova submetidos à compressão axial, flexão simples sob carga centrada e fadiga. As medições foram feitas em três traços de concreto: 1) concreto sem borracha (denominado na presente pesquisa por concreto de referência); 2) concreto com borracha e consumo de cimento igual ao de referência; e 3) concreto com borracha e acréscimo de cimento até a obtenção da resistência do concreto de referência. Os resultados obtidos mostram que a adição de borracha provoca redução na resistência mecânica do concreto, o que pode reduzir as aplicações deste novo material. A presença da borracha também conferiu um menor módulo de elasticidade ao concreto, o que pode ser desejável em situações envolvendo ações de impacto, forças dinâmicas e fadiga. Além dessa vantagem, a aplicação da borracha de pneu no concreto contribui na reciclagem de um material poluente e que normalmente é descartado no meio ambiente. Palavras-chave: concreto; borracha de pneu; propriedades mecânicas. ABSTRACTThis study discusses the mechanical properties of concrete, elaborated from the partial replacement of fine aggregate by crushed rubber. It was made experimental tests in specimens submitted to axial compression, Young's modulus (stiffness), three-point bending flexural and fatigue. The measurements were performed on three mixtures: 1) concrete without rubber (denominated as reference concrete), 2) concrete with rubber and the consumption of cement equal of reference and 3) concrete with rubber and the addition of cement on the mixture until it obtains the same strength of the reference concrete. The results have indicated that adding rubber in concrete decreases the strength, which could reduce the application of this new material. The rubber also decreased the elastic modulus; this could improve the behavior of materials in situations involving impact actions, dynamics loads and fatigue. Furthermore, this new composite contributes on rubber tire recycling processes.

Double-torsion tests were carried out on a commercial ceramic floor tile to verify whether this test is suitable for determining the R-curve of ceramics. The instantaneous crack length was obtained by means of compliance calibration, and it was found that the experimental compliance underestimates the real crack length. The load vs. displacement curves were also found to drop after maximum loading, causing the stress intensity factor to decline. The R-curves were calculated by two methods: linear elastic fracture mechanics and the energetic method. It was obtained that the average values of crack resistance, R, and the double of the work of fracture, 2 × gwof, did not depend on notch length, a0, which is a highly relevant finding, indicating that these parameters were less dependent on the test specimen's geometry. The proposal was to use small notches, which produce long stable crack propagation paths that in turn are particularly important in the case of coarse microstructures

This work presents a Modelica model for an ammonia stripper that is used to process waste (digestate) from a biogas production unit. The model includes the chemical balance equations between species in the liquid and gas, and includes the exchanges between both phases and the energy consumption of the unit. Results show the expected behaviour with an increasing pH with time, with further validation and calibration being necessary once experimental results are available. This is a novel use of Modelica designed to expand the library of processes that are simulated using this approach.

The introduction of biodiesel to commercial diesel is being increased every year. The need to check this addition to the engine and lubricant is important for automakers and internal combustion engine manufacturers. The oil analysis technique is a type of predictive maintenance, done by collecting oil from equipment and analyzing it later in the laboratory, or by analyzing it directly and continuously in on-line systems. In internal combustion engines, all parts have a pre-established service life, longer or shorter, according to the specific function assigned to it. By analyzing the oil, the condition of these parts can be monitored. The oils analysis reveals the first signs of wear of a component. The identification is made based on the study of the number of particles, size, shape and composition thereof, present in the lubricant samples, which provide accurate information about the conditions of the moving surfaces without the need to disassemble the assembly to which these parts belongs. In this work a lubricant contamination by biodiesels were made to simulate possible scenarios within an internal combustion engine.The lubricant recommended by an engine manufacturer was "contaminated" with commercial diesel and with different percentages and types of biodiesel. After this "contamination" they were placed in a pin on disk device under certain conditions.Through the analyzes of the lubricants extracted from the Pin on disk Equipment after the tests, some analysis were carried out in order to study the effects of using biodiesel in the internal combustion engine.These analyzes consisted of Flash point, analytical ferrography, monitoring of ferrous particles generated, viscosity, viscosity index, basicity index and X-ray spectrometry.Among the results obtained it is observed that for a 5% contamination of animal biodiesel there was an increase in the viscosity index. Conversely, the contamination of 5% of animal + vegetable biodiesel decreased the viscosity index in relation to Diesel B5. We also found that these biodiesel additions were not detrimental to the engine and lubricant at the mix ratios and test conditions used.