Concreto de alto desempenho em ambientes com baixas temperaturas
Data
2017-11-15
Autores
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Biblioteca Digital de Teses e Dissertações da USP
Universidade de São Paulo
Escola de Engenharia de São Carlos
Universidade de São Paulo
Escola de Engenharia de São Carlos
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O objetivo de colaborar com o equacionamento da problemática do crescimento populacional por meio de uma proposta viável economicamente, e com vantagens tecnológicas com vistas à durabilidade para a armazenagem de gêneros alimentícios em baixas temperaturas motivou o desenvolvimento desta pesquisa, na qual se propõe o uso do concreto como material alternativo para a construção de sistemas de guarda e conservação de alimentos. A partir de um adequado método de dosagem e da tecnologia desenvolvida pelo grupo de pesquisadores do Laboratório de Materiais Avançados à Base de Cimento, foram elaborados dois concretos diferenciados pela incorporação ou não de ar. A durabilidade do concreto para ambientes com baixas temperaturas tem sido relacionada a um sistema de vazios de ar com volume de 6 '+ OU -' 1 % e adequado espaçamento entre as bolhas de ar. O desempenho desses concretos em ambientes com baixas temperaturas foi avaliado acondicionando-os em uma câmara fria com temperatura de - 35 ± 2 graus Celsius. A sanidade dos corpos-de-prova foi monitorada por meio de ensaios não destrutivos (i.e. determinação da freqüência natural). O período de exposição foi de trinta e cinco dias, sendo que após o sétimo dia ocorreu a estabilização dos valores da freqüência natural dos corpos-de-prova. Os dois tipos de concretos ensaiados - com ar incorporado e sem ar incorporado - mostraram-se resistentes nestas condições de ensaio. Os resultados obtidos demonstram que os concretos, de acordo com o método utilizado, atendem a todos os requisitos para os quais foram projetados
The aim to collaborate with the set out of the world population increase problem, using a feasible and economical proposal, with technology advantages, destined to store foodstuff in low temperatures, motivated the development of this research, that suggests concrete as an alternative material to storage and conservation foodstuff system construction. Starting from the concrete design with an adequate method, and based on the technology developed by worker group of Laboratory of Advanced Cement Based Materials, were designed two kinds of concrete: with and without incorporated air. The durability of concrete in low temperatures environment were related to air voids system with 6 '+ OU -' 1% of air content, and to adequate spacing between air voids. The concrete behaviour in low temperatures environment was evaluated placing the specimens in a cold chamber, whose temperatures were about -35 '+ OU -' 2 Celsius degrees. The integrity of the specimens was evaluated by non-destructive method (determination of natural frequency). The exposure period of the specimens was thirty five days, but at seventh day the natural frequencies values were stabilized. Both kind of concrete were resistant in this condition. The obtained results show that concretes, in conformity to the used methodology, performed all requirement for that were designed
The aim to collaborate with the set out of the world population increase problem, using a feasible and economical proposal, with technology advantages, destined to store foodstuff in low temperatures, motivated the development of this research, that suggests concrete as an alternative material to storage and conservation foodstuff system construction. Starting from the concrete design with an adequate method, and based on the technology developed by worker group of Laboratory of Advanced Cement Based Materials, were designed two kinds of concrete: with and without incorporated air. The durability of concrete in low temperatures environment were related to air voids system with 6 '+ OU -' 1% of air content, and to adequate spacing between air voids. The concrete behaviour in low temperatures environment was evaluated placing the specimens in a cold chamber, whose temperatures were about -35 '+ OU -' 2 Celsius degrees. The integrity of the specimens was evaluated by non-destructive method (determination of natural frequency). The exposure period of the specimens was thirty five days, but at seventh day the natural frequencies values were stabilized. Both kind of concrete were resistant in this condition. The obtained results show that concretes, in conformity to the used methodology, performed all requirement for that were designed
Palavras-chave
ar incorporado, freqüência natural, durabilidade, conservação de alimentos, congelamento, concreto de alto desempenho, baixas temperaturas, low temperatures, incorporated air, high performance concrete, frost, foodstuff conservation, durability, natural frequency