Diagnosing and understanding the properties of concrete structures allows its use in more effective ways that neither compromise application nor impose safety risks or waste materials. Several tests can be performed for this purpose, differing with regards to diagnostic precision, complexity of execution, costs, need of specific apparatus, and others. Specifications from standards must be followed to assure the durability of concrete structures, such as Eurocode 1 (EN 1992‐1) and EN 206 in Europe. This study determined the volume and the distribution of pores of four concrete compositions with distinct water/cement ratio, cement consumption, and compressive strength, through tests of mercury intrusion porosimetry (MIP) and 3D microtomography. Results showed high correlation coefficients between the tests for assessing voids and compressive strength. Comparatively, the 3D microtomography test presented linear relation to the specifications of mixtures, although MIP indicated discrepancies for mixture 2.
Masonry has been widely used as a construction method. However, there is a lack of information on its fire behavior due to the multitude of variables that could influence this method. This paper aimed to identify the influence of loading and mortar coating thickness on the fire behavior of masonry. Hence, six masonries made of clay tiles laid with mortar were evaluated. The mortar coating had a thickness of 25 mm on the face not exposed to high temperatures, while the fire-exposed face had thicknesses of 0, 15, and 25 mm. For each mortar coating thickness, two specimens were tested, with and without loading of 10 tf/m. The real-scale specimens were subjected to the standard ISO 834 fire curve for four hours, during which the properties of stability, airtightness, and thermal insulation were assessed. Results showed that loaded specimens yielded smaller deformations than unloaded ones. Samples that lacked mortar coating on the fire-exposed face underwent fire resistance decrease of 27.5%, while the ones with 15 mm decreased by 58.1%, and the ones with 25 mm decreased by 41.0%. As mortar coating thickness increased, the plane deformations decreased from 40 mm to 29 mm and the thermal insulation properties of the walls improved significantly. For specimens with mortar coating thickness of 25 mm, the load application resulted in a reduction of 23.8% of the thermal insulation, while the unloaded specimen showed a decrease of 43.3%, as well as a modification of its fire-resistance rating.
Resumo O copolímero etileno acetato de vinila (EVA) é largamente utilizado na indústria calçadista. Entretanto, a geração de resíduos no processo de fabricação é bastante significativa. Com a implementação da norma de desempenho, NBR 15575, os projetos de construções habitacionais devem atender aos níveis de desempenho exigidos. Dentre os requisitos prescritos pela norma está a isolação ao ruído de impacto entre pisos, a qual pode ser otimizada com a utilização de materiais de baixa massa específica. Nesse contexto, este artigo visa desenvolver uma argamassa leve, a partir da incorporação de EVA proveniente da indústria calçadista, a ser utilizada como contrapiso para isolamento acústico. Para tanto, fez-se um estudo por meio de ensaios de resistência à compressão e à tração, bem como nível de pressão sonora de impacto padronizado ponderado, realizado em câmara normatizada. Foram desenvolvidos cinco traços, com proporções de 20%, 40%, 60%, 80% e 100% de substituição da agregado miúdo por EVA, além do contrapiso convencional. Foram moldadas placas de 1 m2 de contrapiso leve, e uma amostra representativa do tamanho da laje com 16 m2, as quais diferiram em 2 dB para o isolamento acústico. O traço com melhor desempenho proporcionou uma redução de 9 dB em relação ao contrapiso convencional, mostrando ser eficaz para utilização como isolante acústico.
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