A carregar...
Publicação
Análise comparativa entre o envelhecimento acelerado e natural de argamassas de cimento visando a correlação entre métodos de avaliação de durabilidade
| Nome: | Descrição: | Tamanho: | Formato: | |
|---|---|---|---|---|
| 2.44 MB | Adobe PDF |
Autores
Orientador(es)
Resumo(s)
Esta dissertação apresenta uma análise comparativa do comportamento de argamassas cimentícias submetidas a dois regimes de envelhecimento: um acelerado, em câmara climática (CE), e um natural (AR), exposto às condições do clima de Bragança, Portugal. O estudo visa estabelecer uma correlação técnica entre os métodos de avaliação de durabilidade, investigando a evolução de propriedades físicas e mecânicas (variação de massa, resistência à flexão e à compressão) em amostras normalizadas.
O programa experimental baseou-se na produção de 99 corpos de prova seguindo o traço 1:3 e areia de referência CEN. O grupo CE foi submetido a 16 etapas semanais de ciclos higrotérmicos cíclicos (35°C/40% UR e -10°C/90% UR), enquanto o grupo AR permaneceu em exposição externa de fevereiro a junho de 2026. A metodologia de análise utiliza o modelo de Coffin-Manson para estimativa de dano por fadiga térmica, confrontando as respostas do material com as variações climáticas reais da região.
Os resultados demonstram que, enquanto o envelhecimento acelerado induz uma estabilização da massa e um processo progressivo de fadiga estrutural, evidenciado pela redução da resistência à flexão devido a microfissurações, o ambiente natural impõe uma dinâmica complexa. Observou-se que as amostras expostas ao ambiente externo apresentaram variações de massa erráticas, correlacionadas aos eventos de precipitação e dessecação sazonal, além de um ganho de resistência à compressão atribuído à cura contínua pelas condições ambientais. A análise comparativa confirma que não existe uma correlação linear universal, evidenciando que a agressividade dos choques térmicos controlados difere da degradação multifatorial observada na natureza. O trabalho conclui com recomendações técnicas para futuros protocolos de ensaio, ressaltando a importância do uso de modelos preditivos calibrados especificamente para as condições climáticas de exposição.
This dissertation presents a comparative analysis of the behavior of cementitious mortars subjected to two aging regimes: an accelerated one, in a climatic chamber (CE), and a natural one (AR), exposed to the conditions of the climate of Bragança, Portugal. The study aims to establish a technical correlation between durability assessment methods, investigating the evolution of physical and mechanical properties (mass variation, flexural strength, and compressive strength) in standardized samples. The experimental program was based on the production of 99 specimens following a 1:3 mix design and CEN reference sand. The CE group was subjected to 16 weekly stages of cyclic hygrothermal cycles (35°C/40% RH and -10°C/90% RH), while the AR group remained in external exposure from February to June 2026. The analysis methodology uses the Coffin-Manson model for thermal fatigue damage estimation, comparing the material's responses with the actual climatic variations of the region. The results demonstrate that, while accelerated aging induces mass stabilization and a progressive process of structural fatigue, evidenced by the reduction in flexural strength due to micro-cracking, the natural environment imposes a complex dynamic. It was observed that samples exposed to the external environment showed erratic mass variations, correlated to precipitation and seasonal drying events, as well as a gain in compressive strength attributed to continuous curing by environmental conditions. The comparative analysis confirms that there is no universal linear correlation, evidencing that the aggressiveness of controlled thermal shocks differs from the multifactorial degradation observed in nature. The work concludes with technical recommendations for future test protocols, highlighting the importance of using predictive models calibrated specifically for the climatic conditions of exposure.
This dissertation presents a comparative analysis of the behavior of cementitious mortars subjected to two aging regimes: an accelerated one, in a climatic chamber (CE), and a natural one (AR), exposed to the conditions of the climate of Bragança, Portugal. The study aims to establish a technical correlation between durability assessment methods, investigating the evolution of physical and mechanical properties (mass variation, flexural strength, and compressive strength) in standardized samples. The experimental program was based on the production of 99 specimens following a 1:3 mix design and CEN reference sand. The CE group was subjected to 16 weekly stages of cyclic hygrothermal cycles (35°C/40% RH and -10°C/90% RH), while the AR group remained in external exposure from February to June 2026. The analysis methodology uses the Coffin-Manson model for thermal fatigue damage estimation, comparing the material's responses with the actual climatic variations of the region. The results demonstrate that, while accelerated aging induces mass stabilization and a progressive process of structural fatigue, evidenced by the reduction in flexural strength due to micro-cracking, the natural environment imposes a complex dynamic. It was observed that samples exposed to the external environment showed erratic mass variations, correlated to precipitation and seasonal drying events, as well as a gain in compressive strength attributed to continuous curing by environmental conditions. The comparative analysis confirms that there is no universal linear correlation, evidencing that the aggressiveness of controlled thermal shocks differs from the multifactorial degradation observed in nature. The work concludes with technical recommendations for future test protocols, highlighting the importance of using predictive models calibrated specifically for the climatic conditions of exposure.
Descrição
Mestrado de dupla diplomação com a UTFPR - Universidade Tecnológica Federal do Paraná
Palavras-chave
Argamassas cimentícias Durabilidade Envelhecimento acelerado Envelhecimento natural Modelo de Coffin-Manson