Caraterização mecânica de alvenaria de blocos de terra comprimida (BTC)
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2018-07-11
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A construção em terra é uma técnica utilizada em todo o mundo e representa uma das formas mais antigas de construir. É uma solução que apresenta diversas vantagens quando comparadas com outras técnicas de construção, nomeadamente bom desempenho térmico e acústico, baixo valor de energia incorporada, elevada resistência ao fogo, permitindo ainda reduzir consideravelmente os custos da construção, uma vez que se trata de um recurso disponível no próprio local ou conseguido a baixos custos. É também um tipo de construção versátil pois permite a utilização de várias técnicas, entre elas a construção de alvenaria de blocos de terra comprimida (BTC). A produção de BTC consiste em compactar, através de meios mecânicos, uma mistura de solo e água num molde, diminuindo os vazios e a porosidade, aumentando assim a sua resistência mecânica. Quando as propriedades do solo não são adequadas ao fabrico dos blocos, recorre-se ao uso de estabilizantes para melhorar as propriedades dos BTC’s. Esta dissertação apresenta uma solução de estabilização química através da adição de cimento e cal hidráulica à mistura de solo e água. Depois de produzidos, os BTC foram avaliados quanto à regularidade dimensional apresentando coeficientes de variação muito baixos e consequentemente uma elevada regularidade dimensional. Foram também ensaiados quanto à sua resistência à compressão e à flexão, tendo sido efetuada a comparação entre BTC no estado saturado e no estado seco, o que permitiu avaliar a sensibilidade dos BTC à presença de água. Com estes ensaios foi possível concluir que os BTC cumprem os requisitos mínimos apresentados nas normas internacionais. Relativamente à influência da presença de água, observou-se também uma redução para quase metade no valor da resistência à compressão e à flexão resultante da saturação dos BTC. De seguida, foram construídos e ensaiados à compressão dois tipos de amostras aqui denominados por prismas e modelos de BTC. De modo a aferir sobre o contributo da argamassa para o comportamento da alvenaria foram efetuados ensaios com e sem argamassa. Relativamente aos ensaios realizados nos prismas e modelos de alvenaria, verificou-se uma redução significativa no valor da resistência à compressão da alvenaria quando comparado com o valor obtido para os BTC. Estes resultados demostraram ainda que a introdução de argamassa nas juntas das amostras melhora o seu comportamento à compressão.
Earth construction is a worldwide used technique, and it represents one of the most ancient construction methods. It consists in a solution which offers several advantages when comparing to other construction techniques, namely a good thermal and acoustic performance, a low builtin power, high fire resistance, and it allows a considerable reduction as well in the construction costs, since it is and available resource which can be found in the local, or that can be obtained at low price. Furthermore, it is also a very versatile construction method, since it allows the integration of several techniques, being among them the construction of CEBs (Compressed Earth Blocks). The CEB production consists in compressing, through mechanical means, a mixture of soil and water inside a mold, decreasing the gaps and the porosity, and increasing, therefore, he mechanical resistance. When the properties of the soil are not well-suited to the fabrication of the blocks, it is necessary to use stabilizers to improve the properties of the CEBs. This dissertation presents a solution for a chemical stabilization, by adding cement and hydraulic lime to the moisture of soil and water. After their production, the CEBs were evaluate regarding the dimensional regularity, presenting very low changing coefficients and, consequently, a high dimensional regularity. They were also assessed regarding their resistance to the compression and flection by doing the comparison between the CEBs in the dry and saturated state, allowing to evaluate the sensitivity of the CEBs in the presence of water. With those experiments, it was possible to conclude that CEBs follow the minimum requirements regarding the international norms. Considering the influence of the presence of water, it was observed a reduction by almost half of the resistance value under compression and under saturation of the CEBs. Afterwards, two types of samples were constructed and assessed under compression, being here denominated by prims and CEB models. To evaluate the contribution of grout in the masonry’s behavior, there were performed some tests which were done with and without grout. Regarding the experiments performed to the prisms and the masonry models, it was observed an important reduction in the masonry’s resistance to compression when comparing to the value obtained in CEB’s tests. These results show that the introduction of grout in the joints of the samples can improve their behavior under compression.
Earth construction is a worldwide used technique, and it represents one of the most ancient construction methods. It consists in a solution which offers several advantages when comparing to other construction techniques, namely a good thermal and acoustic performance, a low builtin power, high fire resistance, and it allows a considerable reduction as well in the construction costs, since it is and available resource which can be found in the local, or that can be obtained at low price. Furthermore, it is also a very versatile construction method, since it allows the integration of several techniques, being among them the construction of CEBs (Compressed Earth Blocks). The CEB production consists in compressing, through mechanical means, a mixture of soil and water inside a mold, decreasing the gaps and the porosity, and increasing, therefore, he mechanical resistance. When the properties of the soil are not well-suited to the fabrication of the blocks, it is necessary to use stabilizers to improve the properties of the CEBs. This dissertation presents a solution for a chemical stabilization, by adding cement and hydraulic lime to the moisture of soil and water. After their production, the CEBs were evaluate regarding the dimensional regularity, presenting very low changing coefficients and, consequently, a high dimensional regularity. They were also assessed regarding their resistance to the compression and flection by doing the comparison between the CEBs in the dry and saturated state, allowing to evaluate the sensitivity of the CEBs in the presence of water. With those experiments, it was possible to conclude that CEBs follow the minimum requirements regarding the international norms. Considering the influence of the presence of water, it was observed a reduction by almost half of the resistance value under compression and under saturation of the CEBs. Afterwards, two types of samples were constructed and assessed under compression, being here denominated by prims and CEB models. To evaluate the contribution of grout in the masonry’s behavior, there were performed some tests which were done with and without grout. Regarding the experiments performed to the prisms and the masonry models, it was observed an important reduction in the masonry’s resistance to compression when comparing to the value obtained in CEB’s tests. These results show that the introduction of grout in the joints of the samples can improve their behavior under compression.
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construção em terra , BTC (clocos de terra comprimida) , caracterização mecânica , compressão e flexão