Loading...
Publication
Betão autocompactável de elevado efeito estético
| Name: | Description: | Size: | Format: | |
|---|---|---|---|---|
| 4.7 MB | Adobe PDF |
Authors
Abstract(s)
As tendências arquitectónicas exigem uma evolução cada vez mais intensa dos materiais de construção. Notoriamente, os edifícios de betão mais emblemáticos expõem cada vez mais a sua estrutura, ao que se chama de ‘betão aparente’. O betão colorido, desenvolvido no último século, é uma solução corrente de ‘betão aparente’. Em edifícios com vida útil longa o betão colorido dispensa uma manutenção tão intensiva quanto os acabamentos superficiais correntes, tornando-se mais económico.
Neste trabalho produziu-se betão colorido através da incorporação de pigmentos na sua composição. Para tal, efectuou-se primeiramente um estudo intensivo em pastas e argamassas igualmente coloridas. Uma vez que o ‘betão aparente’ exige um bom acabamento superficial, considerou-se neste estudo o uso de Betão Autocompactável. Atendendo à disponibilidade de materiais na Região Autónoma da Madeira foram utilizados cimentos cinzentos, cinzas volantes e agregados vulcânicos britados. Analisou-se a incorporação de pigmentos líquidos de cor: amarelo, laranja, vermelho, castanho, preto e verde. Investigou-se e quantificou-se a influência dos diversos pigmentos nas propriedades do estado fresco e na resistência à compressão em argamassas e em betões. Codificaram-se as cores das pastas, argamassas e betões em diferentes idades através do ‘software’ Just Color Picker, utilizando a escala HSV em valores de matiz, saturação e luminosidade e a escala RGB (quantificando a percentagem de vermelho, verde e azul presente na cor).
Os resultados demonstraram que a incorporação de cinzas volantes, a passagem do tempo e exposição ambiental e o tipo de cimento são os parâmetros mais relevantes na alteração da cor. A adição de pigmentos tem grande influência na deformabilidade quer de pastas, quer de argamassas e betões, no entanto a nível da resistência a influência é reduzida.
A parte experimental deste trabalho foi concluída com a execução de uma pequena parede que foi betonada usando betões de várias cores. No que concerne à ‘interface’ entre os diversos betões, verificou-se que o tempo entre betonagens é crucial para a aderência entre betões de cores diferentes, observando-se que a fraca aderência entre betões provocou uma fragilidade na zona de ‘interface’ entre eles.
The architectural trends require an increase in the evolution of construction materials. Notoriously the most emblematic concrete buildings expose more and more their structure, the so-called 'exposed concrete'. The colored concrete, developed in the last century, is a solution of 'exposed concrete'. In buildings with long life cycle colored concrete does not require an intensive maintenance as current surface finishing, making it more economical. In this work colored concrete was produced by incorporating pigments into its composition. To this end, firstly colored pastes and mortars were studied. Since the 'exposed concrete' requires a good surface finishing, it was considered in this study the use of Self Compacting Concrete. Being aware about the availability of materials in Madeira Island gray cement, fly ash and volcanic crushed aggregates were used. The incorporation of liquid pigments of color (yellow, orange, red, brown, black and green) was analysed. The effect of various pigments on the properties of the fresh state and the compressive strength in mortar and concrete were investigated and quantified. The colors of the pastes, mortars and concretes were coded at different ages through the 'software' Just Color Picker, using the scale HSV on values of hue, saturation and brightness and RGB scale (quantifying the percentage of red, green and blue into the color). The results showed that incorporation of fly ash, the passage of time and environmental exposure and the kind of cement are the most relevant parameters in the color change. The addition of pigments has markedly influence on deformability of pastes, mortars and concretes, however the influence in the concrete strength is almost neglected. The experimental part of this work was ended with the construction of a small wall using different colored concretes. In regarding to the concrete interfaces, it was observed that the time between the castings is crucial for the connection of different colored concretes. Therefore, it was observed that the weak connection between different colored concretes reduced notably the concrete strength in the interface zone.
The architectural trends require an increase in the evolution of construction materials. Notoriously the most emblematic concrete buildings expose more and more their structure, the so-called 'exposed concrete'. The colored concrete, developed in the last century, is a solution of 'exposed concrete'. In buildings with long life cycle colored concrete does not require an intensive maintenance as current surface finishing, making it more economical. In this work colored concrete was produced by incorporating pigments into its composition. To this end, firstly colored pastes and mortars were studied. Since the 'exposed concrete' requires a good surface finishing, it was considered in this study the use of Self Compacting Concrete. Being aware about the availability of materials in Madeira Island gray cement, fly ash and volcanic crushed aggregates were used. The incorporation of liquid pigments of color (yellow, orange, red, brown, black and green) was analysed. The effect of various pigments on the properties of the fresh state and the compressive strength in mortar and concrete were investigated and quantified. The colors of the pastes, mortars and concretes were coded at different ages through the 'software' Just Color Picker, using the scale HSV on values of hue, saturation and brightness and RGB scale (quantifying the percentage of red, green and blue into the color). The results showed that incorporation of fly ash, the passage of time and environmental exposure and the kind of cement are the most relevant parameters in the color change. The addition of pigments has markedly influence on deformability of pastes, mortars and concretes, however the influence in the concrete strength is almost neglected. The experimental part of this work was ended with the construction of a small wall using different colored concretes. In regarding to the concrete interfaces, it was observed that the time between the castings is crucial for the connection of different colored concretes. Therefore, it was observed that the weak connection between different colored concretes reduced notably the concrete strength in the interface zone.
Description
Keywords
Betão colorido Pigmentos Cor Betão autocompactável Resistência Engenharia Civil . Faculdade de Ciências Exatas e da Engenharia