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Caracterização experimental de betões pré-misturados a seco
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Abstract(s)
Devido à situação atual do setor da construção civil, existe a preocupação e necessidade de procurar soluções competitivas e eficientes para satisfazer exigências e problemas encontrados no dia-a-dia da construção. Portanto, o Laboratório Cimentos Madeira desenvolveu um novo produto, denominado por Betomix, com o objetivo de responder a exigências que se colocam pontualmente.
No trabalho aqui apresentado, pretendeu-se estudar as características mecânicas e o comportamento reológico do betão pré-misturado a seco Betomix. Esse material é especialmente adequado para facilitar a utilização de betão em obras de difícil acesso e em obras que têm como objetivo a execução ou a reparação de pequenos elementos de betão. Para além disso, este é um material de fácil preparação, dado que apenas necessita da adição em obra de uma determinada quantidade de água. Assim, para preparação deste tipo de betão, não é necessário conhecer a composição do mesmo, dado que as quantidades dos agregados, cimento, adjuvantes e eventuais adições são controladas em central, garantindo uma maior homogeneidade do produto aplicado.
Para avaliar as principais características do Betomix, neste trabalho, determinaram-se algumas das suas propriedades, tais como resistência à tração, resistência à compressão, módulo de elasticidade e retração. De referir ainda que os correspondentes ensaios foram também realizados com um betão pronto convencional, da mesma classe de resistência do betão prémisturado a seco, que serviu de referência, com o objetivo de comparar esses dois tipos de betão. De notar ainda que a composição dos dois tipos de betão estudados foi totalmente estabelecida pelo Laboratório Cimentos Madeira.
Nesta dissertação são apresentadas as características, as vantagens e desvantagens do betão pré-misturado a seco. Para além disso, são também explicados todos os ensaios realizados assim como os procedimentos e normas adotados. Os ensaios foram realizados no Laboratório Cimentos Madeira e no Laboratório Regional de Engenharia Civil da Região Autónoma da Madeira.
Os resultados obtidos mostram que o aumento do tempo entre a pré-mistura e a execução da amassadura de betão afeta significativamente várias propriedades do betão Betomix, entre elas a resistência à compressão, resistência à tração e módulo de elasticidade. Por outro lado, a retração do Betomix parece não ter sido influenciada de forma relevante pelo tempo após a pré-mistura. Verificou-se ainda que as equações preconizadas na NP EN 1992-1-1 (2010) para estimar a resistência à compressão, a resistência à tração e o módulo de elasticidade, como função da resistência à compressão, não se aplicam ao Betomix.
Due to the current situation of the construction industry, there is a concern and need to seek competitive and efficient solutions to meet the demands and problems encountered in the construction day-to-day. Therefore, Cimentos Madeira Laboratory has developed a new product, called Betomix, in order to respond to requirements that arise on time. In the work presented here, it was intended to study the mechanical characteristics and the rheological behavior of Betomix pre-mixed dry concrete. This material is especially suitable for facilitating the use of concrete in difficult-to-access works and in works whose purpose is the execution or repair of small concrete elements. In addition, this is an easy-to-prepare material, since it only requires the addition of a certain amount of water on the job site. Thus, for the preparation of this type of concrete, it is not necessary to know the composition of the concrete, since the quantities of aggregates, cement, additives and eventual additions are controlled in the plant, guaranteeing a greater homogeneity of the applied product. In order to evaluate the main characteristics of Betomix, some properties were determined in this work, such as tensile strength, compressive strength, modulus of elasticity and retraction. It should also be noted that the corresponding tests were also carried out with a conventional ready-mix concrete, of the same strength class as the pre-mixed dry concrete, which served as a reference, in order to compare these two types of concrete. It should also be noted that the composition of the two types of concrete studied was fully established by Cimentos Madeira Laboratory. In this dissertation the characteristics, advantages and disadvantages of pre-mixed concrete are presented. In addition, all tests performed as well as the procedures and standards adopted are also explained. The tests were carried out in the Cimentos Madeira Laboratory and in the Regional Laboratory of Civil Engineering of the Autonomous Region of Madeira. The results show that the increase in the time between the premix and the execution of concrete mixing significantly affects several properties of Betomix concrete, including compressive strength, tensile strength and modulus of elasticity. On the other hand, the Betomix retraction does not appear to have been significantly influenced by the time after premixing. It was also verified that the equations recommended in NP EN 1992-1-1 (2010) to estimate the compressive strength, tensile strength and modulus of elasticity as a function of the compressive strength do not apply to Betomix.
Due to the current situation of the construction industry, there is a concern and need to seek competitive and efficient solutions to meet the demands and problems encountered in the construction day-to-day. Therefore, Cimentos Madeira Laboratory has developed a new product, called Betomix, in order to respond to requirements that arise on time. In the work presented here, it was intended to study the mechanical characteristics and the rheological behavior of Betomix pre-mixed dry concrete. This material is especially suitable for facilitating the use of concrete in difficult-to-access works and in works whose purpose is the execution or repair of small concrete elements. In addition, this is an easy-to-prepare material, since it only requires the addition of a certain amount of water on the job site. Thus, for the preparation of this type of concrete, it is not necessary to know the composition of the concrete, since the quantities of aggregates, cement, additives and eventual additions are controlled in the plant, guaranteeing a greater homogeneity of the applied product. In order to evaluate the main characteristics of Betomix, some properties were determined in this work, such as tensile strength, compressive strength, modulus of elasticity and retraction. It should also be noted that the corresponding tests were also carried out with a conventional ready-mix concrete, of the same strength class as the pre-mixed dry concrete, which served as a reference, in order to compare these two types of concrete. It should also be noted that the composition of the two types of concrete studied was fully established by Cimentos Madeira Laboratory. In this dissertation the characteristics, advantages and disadvantages of pre-mixed concrete are presented. In addition, all tests performed as well as the procedures and standards adopted are also explained. The tests were carried out in the Cimentos Madeira Laboratory and in the Regional Laboratory of Civil Engineering of the Autonomous Region of Madeira. The results show that the increase in the time between the premix and the execution of concrete mixing significantly affects several properties of Betomix concrete, including compressive strength, tensile strength and modulus of elasticity. On the other hand, the Betomix retraction does not appear to have been significantly influenced by the time after premixing. It was also verified that the equations recommended in NP EN 1992-1-1 (2010) to estimate the compressive strength, tensile strength and modulus of elasticity as a function of the compressive strength do not apply to Betomix.
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Keywords
Betões pré-misturados a seco Betomix Engenharia Civil . Faculdade de Ciências Exatas e da Engenharia