Propriedades hígricas de materiais e patologia de elementos construtivos

Existe cada vez mais nos tempos que correm uma preocupação com os recursos naturais existentes e com a forma de como estes são explorados. Desta forma todas as indústrias nas quais se insere a da construção civil, têm demonstrado uma mudança no que se refere ao uso de matérias-primas. Assim, o sector tem-se focado no uso de resíduos provenientes da construção e demolição para a criação de betões. Outra problemática existente refere-se à durabilidade das estruturas. Existindo inúmeros estudos onde se verifica que as estruturas apresentam precocemente altos níveis de degradação, o que implica um aumento de custos. Assim, a presente investigação debruçou-se sobre o tema da durabilidade do betão auto-compactável com o uso de agregados grossos reciclados. Para isso, foram produzidos quatro tipos de betão diferente, sendo um o betão de referência e os restantes com 20%, 40% e 100% de substituição de agregados. Para avaliar as propriedades relacionadas à durabilidade, realizaram-se os seguintes ensaios, permeabilidade ao oxigénio, permeabilidade à água, absorção capilar e profundidade de penetração de água. Desta forma e com os resultados obtidos, conclui-se que é viável tecnicamente, o uso de agregados reciclados no betão auto-compactável pra fins estruturais.Humidity, of all the pathological factors, is the one that affects constructions the most. So, because of that, having the knowledge of the hygric properties of the building materials gives us the possibility to choose them more coherently for a more efficient functioning of the construtive systems. Initially, a compilation of concepts and definitions of the main properties of mortar and concrete was made, as well as of the main hygric properties of the building materials. The mains forms of humidity manifestation were also mentioned, as well as some of the methods of how to diagnose them. Also some solutions to the referred forms of humidity manifestation were presented. The experimental section of this dissertation had as its objective ascertain the hygric properties of five series of mortar and concrete C25/30 factory made. One of these mortars is a commercial pré-dosed mortar and the rest have cement, hydraulic lime, metakaolin and a geopolymeric binder in their composition. Various experiments were made in order to determine the hygric properties of the mortars, such as, the determination of its humidity content, water absorption through capillarity, water absorption through immersion with vacuum, permability to oxygen and water. In order to complement these experiments it was also determined the resistance to compression of each one of the different mortars. For all of the experiments, the mortars before tested were subjected to a simplified process of the method of pré-conditioning of test-speciments RILEM TC 116-PCD. However, for the experiment with water absorption through capillarity the test-specimens were also subjected to a different environment beforehand, in which they went through a 24 hour drying at 110ºC. This way it was possible to compare the results of the experiment when the test-speciments were subjected to two different environments. From the final results of the experiments it was possible to determine which one of the mortars is more suitable to use in the reparation of anomalies caused by humidity