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Abstract The ultrasonic pulse velocity, obtained by ultrasonic non-destructive testing, has been applied to evaluate the concrete integrity. The attenuation parameters have shown more sensitivity to damage detection in the microstructure of concrete since they consider the entire ultrasonic waveform. However, it is still necessary to evaluate the sensitivity of those parameters to thermally damaged concrete. This work aims to assess the behavior and the sensitivity of the following ultrasonic parameters: pulse and group velocities, maximum amplitude, total energy, accumulated energy, and time instants corresponding to 25%, 50%, and 75% of the energy, in detecting changes due to thermal degradation of the concrete. A sample of 39 cylindrical concrete specimens with 100 mm in diameter and 300 mm in length and C25 strength class was used. The sample was distributed into 5 groups heated between 20 and 400 ºC until the internal temperature of the specimens became homogeneous. The groups were cooled inside a muffle furnace until reaching 150 ºC. Subsequently, they were exposed to the ambient temperature and humidity of the laboratory environment for, at least, 24 hours prior to the tests of mass loss, ultrasound, and compressive strength. The results show that the ultrasonic parameters are sensitive to the thermal degradation of the concrete. The pulse velocity, the accumulated energy, and the time instants corresponding to percentages of the energy decrease monotonically as the temperature increases. The group velocity shows significant dispersions, while the maximum amplitude and the total energy increase at 200 ºC. The results led to the conclusion that the pulse velocity is the least sensitive parameter, while the time instants corresponding to 25%, 50%, and 75% of the energy are the most sensitive parameters in detecting changes due to thermal degradation of the concrete.

Este artigo teve como objeto de pesquisa a avaliação de acervos digitais de museus de Moda baseados na web. Foi apresentada primeiramente uma contextualização dos museus no mundo virtual, identificando os tipos de sites museológicos existentes e os conceitos gerais de usabilidade. Em seguida, através de um estudo comparativo das heurísticas e recomendações de usabilidade de Nielsen, Bastien & Scapin, e Jordan, foram identificadas as mais adequadas para aplicação neste tipo de acervo, principalmente no que se refere à interação do usuário e ao estímulo de processos cognitivos para estabelecer estes espaços virtuais como locais de aprendizado, sem depender do espaço físico. Optou-se pelas heurísticas de Nielsen, que foram então aplicadas em uma avaliação da interface do site do Australian Dress Register, vinculado ao Powerhouse Museum Science + Design. Os resultados preliminares permitiram identificar as recomendações de usabilidade mais propícias para avaliar a estrutura e organização de sites de acervos digitais de museus de Moda.

Nine acetamidochalcones were synthesized and evaluated as antinociceptive agents using the mice writhing test. Given intraperitoneally all the compounds were more effective than the two reference analgesic drugs (acetylsalicylic acid and acetaminophen) used for comparison. N-{4-[(2E)-3-(4-nitrophenyl)prop-2-enoyl]phenyl}acetamide (6) was the most effective compound and was therefore selected for more detailed studies. It caused dose-related inhibition in the writhing test, being about 32 to 34-fold more potent than the standard drugs. It was also effective in the second phase of the formalin test and the capsaicin test. These acetamidochalcones, especially compound 6, might be further used as models to obtain new and more potent analgesic drugs.

The distance of concrete structures from the sea is an important aspect when studying the deleterious effect of airborne salinity in marine environment zone. It permits to know how the durability of structures is affected by increasing the distance from the sea. This paper presents results of an experimental work on assessing the effect of the distance from sea on chloride aggressiveness, considering both the airborne salinity and chloride content in concrete specimens located at different distances from sea. This study has been carried out at Joao Pessoa, capital of the State of Paraiba, located in the northeast part of Brazil. The results indicated a drastic reduction of chloride deposition from marine aerosol, especially along the first 200 meters from the sea. Similar behavior was observed in the concrete specimens, even though the reduction has been less pronounced. Although more research is necessary, the differences in the rates of chloride decrease may be explained by different reasons, including the different chloride concentration in air and on concrete surface, the phenomena related to the skin effect and surface washing by rain.

O método de velocidade de propagação de ondas ultra-sônicas é uma técnica que envolve a propagação de ondas através do material que se quer avaliar e é caracterizado por ser um método de ensaio não destrutivo, podendo ser utilizado para avaliar a qualidade do material concreto. Através do uso desse método, é possível, por exemplo, obter in situ a espessura de lajes de concreto e estimar a resistência à compressão do concreto. Este trabalho tem por objetivo apresentar resultados da aplicação do método de propagação de ondas ultra-sônicas na detecção das primeiras fissuras em vigas de concreto armado solicitadas à flexão simples. O método é também utilizado para avaliar a resistência à compressão do concreto. Os resultados comprovam que o método de propagação de ondas ultra-sônicas pode ser utilizado para estimar a resistência à compressão do concreto e, se corretamente utilizado, pode ser útil em ensaios de flexão de vigas de concreto armado para detecção do início de fissuração do concreto.

O desprendimento dos laminados de plásticos reforçados com fibras da face inferior tracionada das vigas reforçadas à flexão é um problema complexo e indesejável, pois ocorre sem aviso, antecipando a ruína da viga reforçada e impossibilitando o total aproveitamento das propriedades resistentes à tração do reforço. Neste trabalho estudou-se o comportamento de vigas de concreto armado, reforçadas à flexão com manta de fibra de carbono, e avaliou-se a incorporação de mecanismos de incremento de ancoragem para evitar o desprendimento prematuro da manta com conseqüente aumento da capacidade resistente à flexão da viga. Nove vigas foram divididas em cinco grupos em conformidade com mecanismo de incremento de ancoragem adotado. Um dos mecanismos, além de evitar o desprendimento prematuro do reforço, também proporcionou incremento na resistência à flexão mais de 95%, em relação à viga sem reforço, e incrementos em torno de 20%, em relação às vigas sem incremento de ancoragem.

A chuva dirigida, chuva carregada pelo vento que possui uma componente horizontal dada pela velocidade do vento, é a maior fonte de umidade que afeta a durabilidade e o desempenho higrotérmico das fachadas das edificações. Este trabalho apresenta uma avaliação do nível de exposição das edificações à chuva dirigida em Florianópolis-SC com o auxílio de índices de chuva dirigida e de índices de chuva dirigida em parede vertical. Para a obtenção desses parâmetros aplicaram-se fórmulas empíricas já existentes na literatura internacional e utilizaram-se dados de velocidade e direção do vento e de precipitação de estações meteorológicas localizadas na Ilha de Santa Catarina e na cidade vizinha de São José. Foram feitas análises para três períodos distintos: (a) 1961-1970, (b) 1991/1993-1996 e (c) setembro de 2005 a agosto de 2006. De acordo com os resultados, a exposição da área de estudo variou de local protegido a exposição alta, sendo as direções sudeste, sul e sudoeste as mais críticas quanto à exposição das fachadas à chuva dirigida. O trabalho traz informações úteis para os projetistas, no intuito de criar projetos mais adequados à proteção das fachadas das edificações na área de estudo, além de trazer contribuições para as áreas de estudo de durabilidade e conforto térmico das edificações.

ABSTRACT Although the ultrasonic pulse velocity (UPV) method has been extensively used to estimate concrete compressive strength, the relationship between UPV and concrete strength is mixture dependent. As a result, the applicability of this method to estimate strength is well known to be limited. Aggregate type, cement type, mixture proportions, and water-cement ratio influence such a relationship. Nevertheless, UPV and strength are both governed by cement hydration, and thus, a relationship between UPV in the cement paste phase and concrete compressive strength would be expected to exist. By not taking into account the type and volume content of aggregates, this relationship could be the same for concrete mixtures with same type of cement and water-cement ratio, regardless the aggregate type used. This study investigates the existence of such a relationship. Concrete mixtures with water-cement ratios of 0.48, 0.55 and 0.64, with different paste volumes were prepared in the laboratory. For each mixture, compressive strength and ultrasonic pulse velocity were evaluated at various ages. The UPV of each concrete phase: paste, fine aggregate, and coarse aggregate, was obtained through paste and mortar specimens. This study indicated that it is possible to establish a unique relationship between the UPV in cement paste phase and the concrete compressive strength. This unique relationship could be applied to several concrete mixtures, greatly expanding the use of the UPV method to estimate compressive strength.

This paper demonstrates the application of the active infrared thermography to detect damage in bonding between concrete and glass fiber reinforced polymer (GFRP). Specimens of concrete and mortar with GFRP externally bonded were prepared and at their interfaces were inserted polystyrene discs to simulate damages. The samples were divided into two groups. In group 1, one sample was correctly bonded by a GFRP plate to the concrete, but in the other three were inserted polystyrene discs which had different diameters to simulate damages in bonding. In group 2, all of the samples contained identical polystyrene discs at their interfaces, but the total thickness of each specimen was different, because the objective was to evaluate the ability of the camera to capture the simulated damage in depth. The experimental procedure was divided into two stages. In the first stage, four types of heating were used to heat samples of group 1: incandescent lamp, kiln, blended lamp and fan heater. Thus, it was possible to detect the damage and to observe its format and length. It was noticed that the infrared images are different depending on the heat source incident on the specimen. Therefore, group 2 was tested only for the more efficient heating (incandescent lamp). In the second stage, the infrared equipment was tested. Some of the parameters that must be inserted in the camera were varied in order to understand their influence on image formation. The results show the effectiveness of infrared thermography to assess adherence in GFRP/concrete interface. In the present work, the best results were obtained when the image is captured towards GFRP/concrete and using incandescent lamp. It was observed that the image and measured temperature suffer significant distortion when a false value was inserted for the parameter emissivity.