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No presente trabalho estuda-se a fenomenologia que explica as anomalias nas argamassas de revestimento, em construções antigas, afetadas por umidade de ascensão e por sais solúveis. Este estudo tem por base os casos diagnosticados nos edifícios históricos (século XIX até meados do século XX) da zona central da Cidade de Pelotas. A revisão realizada permitiu conhecer, de forma mais aprofundada, a fenomenologia do transporte de umidade e sais em meio poroso, bem como, os vários modelos representativos existentes (Glaser, Freitas, Abrantes e Crausse, Hall-Hoff, Scherer, Christopher Hall e L. Pel e K. Kopinga). Devido ao grau de complexidade desses modelos na aplicação como ferramenta de escolha de materiais de revestimento à base de argamassa, desenvolveu-se um modelo matemático simplificado para a avaliação da ascensão de umidades em paredes de alvenaria. Teoricamente foram identificadas,para modelação, as características físicas das argamassas definidas pela sua composição. Variáveis comoa proporção de agregados/aglomerantes, que definem o esqueleto sólido, bem comoo tipo de aglomerante que definea porosidade finadas argamassas foram estabelecidas para o estudo experimental. Para este estudo foram propostas argamassas de reabilitação à partir das caracteristicas dos materiais identificadas em amostras de revestimento extraídos das paredes de um edifício selecionado entre seis edifícios da Cidade de Pelotas que apresentavam anomalias de umidades e sais solúveis. Os ensaios realizados nas argamassas de reabilitação propostas, de acordo com as normas vigentes, compreenderam as determinações de massa volúmica, índice de vazios, absorção de água por capilaridade, secagem da água absorvida, resistência mecânica e teor de sais solúveis. Foram determinados, também, a resistência de aderência ao suporte, a permeabilidade à água e o teor de sais em argamassas aplicadas em painéis de alvenaria. Por fim observou-se, em painéis de alvenaria revestidos com as argamassas de reabilitação, a evolução da ascensão capilar de umidade ao longo do tempo. Os resultados obtidos nos ensaios das argamassas permitiram colocar em relevância os aspectos comportamentais das argamassas propostas em relação à estrutura do esqueleto, determinando maior ou menor porosidade e, consequentemente, o transporte da água absorvida por ascensão; a umedecida. A observação da evolução da umidade ascensional nos painéis confirma o modelo teórico proposto e traduz a variação da água ascensional em ambiente com taxa de evaporação constante, pela área molhada da parede compreendida pela altura do perfil hidráulico medido num tempo t. Como o perfil hidráulico, sob efeito da evaporação, também sofre uma atenuação no tempo devido a ação da gravidade, determinando, neste caso, que o modelo teórico–experimental pode ser melhor representado por uma função logarítmica.
The present work studies the phenomenology that explains coating mortar anomalies in old buildings affected by rising damp and soluble salts. This study is based on diagnosed cases in historic buildings (XIX century to mid XX century) in the central zone of the City of Pelotas. The review permitted a more accurate understanding of the phenomenology of moisture and salt transport in porous media, as well as the various existing representative models (Glaser, Freitas, Abrantes and Crausse, Hall-Hoff, Scherer, Christopher Hall and L. Pel and K. Kopinga). Due to the complexity of these models in their application and the choice of mortar coating materials, a simplified mathematical model for the evaluation of humidity rise in masonry walls was developed. Theoretically, the physical characteristics of mortars were defined by their compositions and identified for modelling purposes. Variables were established for this experimental study such as the binder/aggregate ratio, which defines the solid skeleton, and the type of binder that identifies the fine porosity in mortars. For the following study, rehabilitation mortars were proposed, based on the identified characteristics of materials in wall coating samples. These samples were taken from a building with moisture and soluble salt anomalies selected from among six others in the City of Pelotas. The tests conducted on the proposed rehabilitation mortars, according to current regulations, comprehend density determinations, void ratio, capillary water absorption, drying of the absorbed water, mechanical strength and soluble salt content. It was also determined the support adhesion strength, the water permeability and the salt content in mortars applied to masonry panels. Finally, it was observedthe evolution of moisture capillary rise in masonry panels coated with rehabilitation mortar over time. The obtained results of the mortar tests added relevance to the behavioral aspects of the proposed mortars, in relation to the skeletal structure, determining greater or lesser porosity and, consequently, the transport of water absorbed by the rise; which is directly related to the capillary porosity and time of wetting of the moistened area. The observation of the evolution of ascending moisture in the panels confirms the proposed theoretical model and translates the variation of the upward water in an environment with constant evaporation rate, with the wall wet area understood by the height of the hydraulic profile measured at a time t. The hydraulic profile, under the effect of evaporation, is alsoreduced due to gravity and determines, in this case, that the theoretical model can be better represented by a logarithmic function.
The present work studies the phenomenology that explains coating mortar anomalies in old buildings affected by rising damp and soluble salts. This study is based on diagnosed cases in historic buildings (XIX century to mid XX century) in the central zone of the City of Pelotas. The review permitted a more accurate understanding of the phenomenology of moisture and salt transport in porous media, as well as the various existing representative models (Glaser, Freitas, Abrantes and Crausse, Hall-Hoff, Scherer, Christopher Hall and L. Pel and K. Kopinga). Due to the complexity of these models in their application and the choice of mortar coating materials, a simplified mathematical model for the evaluation of humidity rise in masonry walls was developed. Theoretically, the physical characteristics of mortars were defined by their compositions and identified for modelling purposes. Variables were established for this experimental study such as the binder/aggregate ratio, which defines the solid skeleton, and the type of binder that identifies the fine porosity in mortars. For the following study, rehabilitation mortars were proposed, based on the identified characteristics of materials in wall coating samples. These samples were taken from a building with moisture and soluble salt anomalies selected from among six others in the City of Pelotas. The tests conducted on the proposed rehabilitation mortars, according to current regulations, comprehend density determinations, void ratio, capillary water absorption, drying of the absorbed water, mechanical strength and soluble salt content. It was also determined the support adhesion strength, the water permeability and the salt content in mortars applied to masonry panels. Finally, it was observedthe evolution of moisture capillary rise in masonry panels coated with rehabilitation mortar over time. The obtained results of the mortar tests added relevance to the behavioral aspects of the proposed mortars, in relation to the skeletal structure, determining greater or lesser porosity and, consequently, the transport of water absorbed by the rise; which is directly related to the capillary porosity and time of wetting of the moistened area. The observation of the evolution of ascending moisture in the panels confirms the proposed theoretical model and translates the variation of the upward water in an environment with constant evaporation rate, with the wall wet area understood by the height of the hydraulic profile measured at a time t. The hydraulic profile, under the effect of evaporation, is alsoreduced due to gravity and determines, in this case, that the theoretical model can be better represented by a logarithmic function.
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Palavras-chave
Argamassa de reabilitação Eflorescências Umidade ascensional Porosidade Transporte