Madeira e seus derivados na construção – caso de estudo de proposta de um material alternativo
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2020-02-13
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Ao longo dos últimos anos, a indústria da construção tem contribuído de forma negativa nos impactos ambientais que o planeta tem sofrido através da elevada utilização de recursos naturais, do elevado consumo de energia e da consequente emissão de gases de efeito de estufa. Desta forma, a sustentabilidade é uma preocupação constante na atualidade, a níveis económico, social e ambiental. O recurso a soluções construtivas mais sustentáveis, nomeadamente através da reutilização e incorporação de materiais em elementos de construção pode contribuir para minimizar o impacto nefasto. Surge assim a possibilidade de reutilizar resíduos ou subprodutos, agrícolas ou silvícolas, incorporando-os em argamassas ou elementos de construção leve. A casca de pinheiro é um resíduo, de origem natural, bastante abundante na floresta portuguesa, geralmente aplicado em jardins, para decoração e para a produção de calor. Tendo em conta a leveza e as propriedades que a caracterizam, pretende-se com este trabalho de investigação analisar o potencial de aplicação em elementos de construção leve. De modo a estudar o potencial de incorporação da casca de pinheiro em elementos de construção, foi analisada inicialmente a granulometria da mesma, recorrendo a dois processos distintos. Verificou-se uma granulometria bastante heterogénea que favorecia a diminuição do volume de vazios, através da existência de partículas finas. Foram estudadas e otimizadas diferentes composições com a incorporação do resíduo em estudo em calda de cimento, produzindo os provetes necessários à realização dos ensaios para examinar as suas propriedades físicas e mecânicas. Os provetes apresentaram resultados promissores no comportamento ao corte, reação ao fogo, aderência a placas cerâmicas e colagem entre si. Relativamente à furação, os resultados foram satisfatórios. No ensaio do teor de absorção de água por capilaridade o resultado obtido não foi o mais desejado, apresentando um coeficiente de absorção de água bastante elevado. No entanto, tal observação não se considerou negativa uma vez que a utilização dos elementos em estudo passa por espaços interiores, não expostos a condições climatéricas adversas. Relativamente à resistência à compressão, os provetes apresentaram valores próximos de 1MPa. Observaram-se ainda modos de rotura semelhantes a um betão corrente. No que diz respeito ao comportamento térmico, os provetes ensaiados alcançaram resultados bastantes positivos, obtendo-se um valor de 0,09 W/mºC para o coeficiente de condutibilidade térmica, números bastantes próximos de isolantes térmicos correntes como a lã de vidro, lã de rocha ou XPS.
For long time that the building industry has been contributing negatively for the environmental impacts. The expressive amount of natural resources usage and energy consumption are the main causes. In addition, the emission of pollutant gases to atmosphere of this industry does not also helps the solution of this problem. Therefore, all sustainable actions are appreciated. Reusing or incorporating are two possible measures that can have a sustainable side. In particular, when we are dealing with waste or by-product. In this context, the possibility of using agricultural or forestry waste products in the manufacturing of mortar or lightweight concrete looks like promising. Pine bark is one example of these products. It has the particularity of being a waste product, natural, local and abundant in the Portuguese reality. As far as we realized there is no tradition of using this material. According to our literature review, pine bark has been using mainly in garden work, decorative purposes or biomass. Taking into account its physical properties the main goal of this research work is to study the potential of application of this by-product in the process of lightweight materials. At the first stage, the granulometry of the pine bark was a concerning. It was concluded that a heterogenic granulometry which includes a certain amount of thin particles is appropriate in order to reduce the level of empty spaces. Different mixtures of pine bark, cement and water were studied, and several samples were prepared in order to assess the physical and mechanical properties of the proposed material. The tested samples presented very good performance in terms of sawing, fire resistance, and adhesion. In terms of drilling the performance was good. In contrast, in terms of water absorption the material has shown some limitation taking into account that it tends to absorb water. It presented an approximate compressive strength of 1MPa and the respective failure modes are similar to concrete. At the same time, in terms of thermal insulation performance the tested samples had good achievement because a 0,09 W/mºC thermal conductivity coefficient was obtained which is quite similar to the common engineered thermal insulation products such as glass wool, rock wool or XPS.
For long time that the building industry has been contributing negatively for the environmental impacts. The expressive amount of natural resources usage and energy consumption are the main causes. In addition, the emission of pollutant gases to atmosphere of this industry does not also helps the solution of this problem. Therefore, all sustainable actions are appreciated. Reusing or incorporating are two possible measures that can have a sustainable side. In particular, when we are dealing with waste or by-product. In this context, the possibility of using agricultural or forestry waste products in the manufacturing of mortar or lightweight concrete looks like promising. Pine bark is one example of these products. It has the particularity of being a waste product, natural, local and abundant in the Portuguese reality. As far as we realized there is no tradition of using this material. According to our literature review, pine bark has been using mainly in garden work, decorative purposes or biomass. Taking into account its physical properties the main goal of this research work is to study the potential of application of this by-product in the process of lightweight materials. At the first stage, the granulometry of the pine bark was a concerning. It was concluded that a heterogenic granulometry which includes a certain amount of thin particles is appropriate in order to reduce the level of empty spaces. Different mixtures of pine bark, cement and water were studied, and several samples were prepared in order to assess the physical and mechanical properties of the proposed material. The tested samples presented very good performance in terms of sawing, fire resistance, and adhesion. In terms of drilling the performance was good. In contrast, in terms of water absorption the material has shown some limitation taking into account that it tends to absorb water. It presented an approximate compressive strength of 1MPa and the respective failure modes are similar to concrete. At the same time, in terms of thermal insulation performance the tested samples had good achievement because a 0,09 W/mºC thermal conductivity coefficient was obtained which is quite similar to the common engineered thermal insulation products such as glass wool, rock wool or XPS.
Descrição
Dissertação apresentada à Universidade de Trás-os-Montes e Alto Douro para cumprimento dos requisitos necessários à obtenção do grau de Mestre em Engenharia Civil
Palavras-chave
casca de pinheiro , sustentabilidade