Publicação
A multi scale approach to the study of lime-cement mortars in masonry
| Resumo: | In masonry constructions, the choice of mortar composition is usually guided by requirements of the final application, which could range from new constructions to conservation projects. Often, lime and cement are combined, to overcome their shortcomings and consequently serve as a suitable binder in masonry mortars. Depending on their proportion in the mixture, it may be possible to obtain the desired range of characteristics in different mechanical properties like strength, stiffness, shrinkage, porosity, and so on. And even though the practice of combining lime and cement in masonry mortars has been around for many years, its benefits have not yet been addressed in a systematic, quantitative manner. Often, seemingly significant differences in the mechanical behavior of mortars do not reflect proportionally in changes in mechanical properties at the masonry level. Thus, the aim of this experimental research is focused on investigating the quantitative benefits of substituting cement with lime in masonry mortars, at the mortar as well as masonry level. Performance indicators have been determined from a structured experimental campaign of mechanical behavior of blended mortars, characterizing several properties for multiple lime-cement mix proportions: workability, compressive and flexural strength, stiffness, drying shrinkage, and open porosity, among others. The factor of aging has also been accounted for, with selected tests being performed up to 365 days, to account for the carbonation of lime in the mortars. Based on the breadth of experimental results that were obtained, patterns were analyzed through regression analyses, to estimate mechanical properties of mix proportions that were not physically tested in the laboratory. From the results obtained, the most suitable proportions were identified and consequently subjected to further experimentation at the masonry level. The response of brick masonry constructed with two different lime-cement mortars was compared with that of cement mortar in masonry, specifically focusing on differences in strength, stiffness, and ductility. In parallel, the influence of lime-cement mortars on the flexural strength of masonry, parallel, and perpendicular to the bed joints was also assessed. The final stage of this research involved quasi-static cyclic loading, to study the in-plane shear response of masonry wall panels, supplemented by experimental information on the shear bond strength of masonry, all focused on assessing the influence of lime-cement mortars compared to a cement mortar. |
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| Autores principais: | Ramesh, Meera |
| Assunto: | Cyclic loads E-modulus Lime-cement mortars Mechanical behavior Unreinforced brick masonry Alvenaria de tijolo não armada Argamassas Argamassas mistas de cal e cimento Carregamento cíclico Comportamento mecânico Módulo de Elasticidade Engenharia e Tecnologia::Engenharia Civil |
| Ano: | 2021 |
| País: | Portugal |
| Tipo de documento: | tese de doutoramento |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade do Minho |
| Idioma: | inglês |
| Origem: | RepositóriUM - Universidade do Minho |
| Resumo: | In masonry constructions, the choice of mortar composition is usually guided by requirements of the final application, which could range from new constructions to conservation projects. Often, lime and cement are combined, to overcome their shortcomings and consequently serve as a suitable binder in masonry mortars. Depending on their proportion in the mixture, it may be possible to obtain the desired range of characteristics in different mechanical properties like strength, stiffness, shrinkage, porosity, and so on. And even though the practice of combining lime and cement in masonry mortars has been around for many years, its benefits have not yet been addressed in a systematic, quantitative manner. Often, seemingly significant differences in the mechanical behavior of mortars do not reflect proportionally in changes in mechanical properties at the masonry level. Thus, the aim of this experimental research is focused on investigating the quantitative benefits of substituting cement with lime in masonry mortars, at the mortar as well as masonry level. Performance indicators have been determined from a structured experimental campaign of mechanical behavior of blended mortars, characterizing several properties for multiple lime-cement mix proportions: workability, compressive and flexural strength, stiffness, drying shrinkage, and open porosity, among others. The factor of aging has also been accounted for, with selected tests being performed up to 365 days, to account for the carbonation of lime in the mortars. Based on the breadth of experimental results that were obtained, patterns were analyzed through regression analyses, to estimate mechanical properties of mix proportions that were not physically tested in the laboratory. From the results obtained, the most suitable proportions were identified and consequently subjected to further experimentation at the masonry level. The response of brick masonry constructed with two different lime-cement mortars was compared with that of cement mortar in masonry, specifically focusing on differences in strength, stiffness, and ductility. In parallel, the influence of lime-cement mortars on the flexural strength of masonry, parallel, and perpendicular to the bed joints was also assessed. The final stage of this research involved quasi-static cyclic loading, to study the in-plane shear response of masonry wall panels, supplemented by experimental information on the shear bond strength of masonry, all focused on assessing the influence of lime-cement mortars compared to a cement mortar. |
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