Avaliação do desempenho de selantes corta fogo para compartimentação de shafts hidráulicos e elétricos

A segurança contra incêndio das edificações é uma necessidade de projeto. As edificações avançam em altura e área, contando com grandes demandas de instalações, obrigando a indústria da construção civil a desenvolver sistemas de vedação capazes de impedir a propagação do fogo através das aberturas e juntas, garantindo a segurança dos usuários e satisfazendo os requisitos de segurança das normas vigentes. Este estudo analisou o desempenho de cinco sistemas de selagem corta-fogo, aplicados em passagens de tubulações hidráulicas e elétricas para compartimentação horizontal, ensaiados em escala real, em situação de incêndio, conforme a curva ISO 834, verificando o tempo de resistência ao fogo (TRF), a estanqueidade e os custos envolvidos. Através do estudo, verificou-se que os sistemas que atingiram TRF acima de 180 minutos foram os que possuem argamassa cimentícia em sua composição, superando o TRF daqueles compostos por placa de lã de rocha com revestimento ablativo, indicando que os sistemas mais econômicos mostraram o melhor desempenho. Todos os selos corta-fogo atingiram TRF igual ou superior a 120 minutos, satisfazendo o TRRF estabelecido pela NBR 14.321.Palavras-chave: Selagem corta fogo; Proteção passiva; Segurança contra incêndio; Compartimentação de edificações.

Análisis experimental de resistencia al fuego de revestimientos de mortero en muros de mampostería estructural

The discussion on fire safety is necessary in Brazilian buildings. Current legislation requires construction with compartmentalized areas separated by walls with structural ceramic blocks capable of resisting fire for an amount of time pre-determined in norm NBR 14432 (ABNT, 2001). However, a lack of building standards requires experimental tests according to NBR 5628 (ABNT, 2001) to determine the necessary configuration to achieve fire resistance. For this purpose, this study analyzed the effect of fire on structural walls covered with a mortar coating. Experiments were conducted in real scale in a standardized vertical oven and the fire growth curve of ISO 834 (ISO, 1999). Three types of walls were tested, each with a different mortar coating: (a) lime; (b) 0.6 kg/m3 polypropylene fiber and 1.2 kg/m3 polypropylene fiber. The mortar coatings were 1.5 cm thick on the side facing the fire and 2.5 cm thick in the outside. The wall was composed of structural blocks measuring 14 cm x 19 cm x 29 cm. Fire experiments evaluated the structure stability, impermeability to hot gases and smoke and thermal insulation of each sample. Results showed that the structural system with 1.2 kg/m3 polypropylene fiber mortar coating obtained the best thermal insulation effect with the longest fire resistance time of 176 min.La discusión sobre seguridad contra incendios es necesaria en los edificios brasileños. La legislación actual exige la construcción con áreas compartimentadas separadas por muros con bloques cerámicos estructurales capaces de resistir el fuego por un tiempo predeterminado en la norma NBR 14432 (ABNT, 2001). Sin embargo, la falta de estándares de construcción requiere pruebas experimentales según NBR 5628 (ABNT, 2001) para determinar la configuración necesaria para lograr la resistencia al fuego. Para ello, este estudio analizó el efecto del fuego en los muros estructurales revestidos con un revestimiento de mortero. Los experimentos se realizaron a escala real en un horno vertical estandarizado y la curva de crecimiento del fuego de ISO 834 (ISO, 1999). Se ensayaron tres tipos de muros, cada uno con un revestimiento de mortero diferente: (a) cal; b) 0,6 kg / m3 de fibra de polipropileno y 1,2 kg / m3 de fibra de polipropileno. Los revestimientos de mortero tenían 1,5 cm de espesor en el lado de cara al fuego y 2,5 cm de espesor en el exterior. El muro estaba compuesto por bloques estructurales de 14 cm x 19 cm x 29 cm. Los experimentos de fuego evaluaron la estabilidad de la estructura, la impermeabilidad a los gases calientes y el humo y el aislamiento térmico de cada muestra. Los resultados mostraron que el sistema estructural con revestimiento de mortero de fibra de polipropileno de 1,2 kg / m3 obtuvo el mejor efecto de aislamiento térmico con el tiempo de resistencia al fuego más largo de 176 min

Evaluation of Ultra-High-Performance Concrete Columns at High Temperatures after 180 Days of Curing

Ultra-high-performance concrete (UHPC) is a material that has high compactness, low porosity, and high mechanical strength, with especially high tensile strength. Due to these characteristics, the behavior of the material when exposed to high temperatures is debatable. The high amount of fibers in the mixture, which makes UHPC present a high tensile strength, is seen as one of the arguments for the good performance of the material when exposed to high temperatures. The objective of this study was to evaluate the behaviors of ultra-high-performance concrete columns with hybrid steel and polypropylene fibers and no loose reinforcements when subjected to elevated temperatures after 180 days of curing. The exposure of concrete with a low age, less than 90 days, to high temperatures results in greater damage to the concrete due to spalling, and because of this, this study sought to evaluate the UHPC with a higher age. Two columns were manufactured with a cross-section of 250 mm × 250 mm and a height of 2800 mm. A heating regime followed the heating curve of standard ISO 834-1. The physical characteristics of the samples were evaluated during and after exposure to high temperatures with measurements of the decreases in the cross-section and surface aspect. Effects on the compressive strength, modulus of elasticity, and apparent density were evaluated with cylindrical test bodies of 100 mm in diameter and 200 mm in height. These samples were cured for 180 days, subjected to the same heating regime, and evaluated after cooling. The results showed an increase in the compressive strength with an increasing temperature up to a factor of 30% at a temperature of 400 °C. The modulus of elasticity and apparent density decreased gradually as the temperature increased, with maximum decreases of 29% and 6%, respectively. Throughout heating, audible cracks were heard from the columns because of spalling. The spalling frequency peaked at an oven temperature of 600 °C, and testing was suspended at 78 min after the complete rupture of a column section. On average, 46.5% of the column cross-sections suffered from spalling