| Name: | Description: | Size: | Format: | |
|---|---|---|---|---|
| 4.3 MB | Adobe PDF |
Abstract(s)
Esta dissertação de mestrado centra-se na importância crescente da adoção da cal como o
material ideal para a conservação de estruturas e edifícios históricos, substituindo o cimento
nessas intervenções. O estudo baseou-se no desenvolvimento de um sistema de quatro
argamassas que se complementam e têm como ligante a cal hidráulica natural (NHL5).
Numa fase inicial, o trabalho consistiu em estudar as características das argamassas existentes
no mercado, de modo a possibilitar a realização de produtos semelhantes. Adicionalmente,
realizou-se o estudo do efeito do tempo nas propriedades das argamassas de cal. As argamassas
foram caracterizadas em conformidade com a norma NP EN 998-1:2017, através da medição
de um conjunto de propriedades fundamentais, incluindo a separação granulométrica, medição
da consistência, ar incluído, densidade em pasta, ensaios de resistência mecânica e absorção
de água por capilaridade. Paralelamente, foram utilizadas técnicas de análise mineralógica
como a espectroscopia de infravermelho por transformada de Fourier (FTIR).
Relativamente aos ensaios exigidos pela norma, e considerando a resistência mecânica das
argamassas, constatou-se que tanto as argamassas comerciais como as formuladas (C1, R1,
AA1 e AF1), são classificadas como CS II. No que concerne ao ensaio de absorção de água
por capilaridade, verificou-se que apenas a formulação correspondente à argamassa de
consolidação (C1) apresentou um coeficiente de absorção de água de acordo com o objetivo.
Este fenómeno sugeriu a presença de aditivos hidrofugantes nas restantes argamassas
comerciais. Face aos resultados obtidos, realizou-se um estudo do tipo e a quantidade de aditivo
hidrofugante (estearato de cálcio (CaE), oleato de sódio (NaO), silano (Sil-A) e resina
hidrofugada (RH)) mais adequado para se obter as propriedades das argamassas desejadas.
Os resultados alcançados permitiram concluir que o silano se apresenta como a melhor
alternativa para garantir a impermeabilização a longo prazo das argamassas de cal, destacandose
pela sua ótima capacidade de redução da absorção de água em quantidades superiores a 0,20
%. Estes resultados foram confirmados pela análise FTIR, que demonstrou um padrão muito
semelhante entre as argamassas, o que, à partida, indica composições mineralógicas
semelhantes.
This master's thesis arises from the growing importance of adopting lime as the ideal material for the conservation of historic structures and buildings, replacing cement in these interventions. The study was based on the development of a system of four mortars that complement each other and have natural hydraulic lime (NHL5) as a binder. Initially, the work consisted in analysing the characteristics of the existing mortars on the market in order to make it possible to produce similar products. Additionally, the effect of time on the properties of lime mortars was studied. The mortars were characterised in accordance to the NP EN 998-1:2017 standard, by measuring a set of fundamental properties, including granulometric separation, consistency measurement, included air, paste density and mechanical strength and capillary water absorption tests. At the same time, mineralogical analysis techniques such as Fourier transform infrared spectroscopy (FTIR) were used. The mortars were characterised, by measuring a set of fundamental properties, including granulometric separation, consistency measurement, included air, paste density, mechanical strength tests and capillary water absorption. At the same time, mineralogical analysis techniques such as Fourier transform infrared spectroscopy (FTIR) were used. As for the tests required by the norms, and considering the mechanical resistance of the mortars, it was found that both the commercial mortars and those formulated (C1, R1, AA1 and AF1) are classified as CS II. Regarding the capillary water absorption test, it was found that only the formulation corresponding to the consolidation mortar (C1) showed a water absorption coefficient in line with the objective. This phenomenon suggested the presence of a water-repellent additive in the remaining mortars. Based on the obtained results, a study was conducted to determine the type and quantity of water-repellent (calcium stearate (CaE), sodium oleate (NaO), silane (Sil-A) and water-repellent resin (RH)) best suited to achieve the desired mortar properties. The results showed that silane is the best alternative for ensuring the long-term waterproofing of the lime mortars under study, with an excellent ability to reduce water absorption in amounts greater than 0.20 %. These results were confirmed by FTIR analysis, which showed that the pattern presented is very similar between the mortars, which, from the outset, suggests similar mineralogical compositions.
This master's thesis arises from the growing importance of adopting lime as the ideal material for the conservation of historic structures and buildings, replacing cement in these interventions. The study was based on the development of a system of four mortars that complement each other and have natural hydraulic lime (NHL5) as a binder. Initially, the work consisted in analysing the characteristics of the existing mortars on the market in order to make it possible to produce similar products. Additionally, the effect of time on the properties of lime mortars was studied. The mortars were characterised in accordance to the NP EN 998-1:2017 standard, by measuring a set of fundamental properties, including granulometric separation, consistency measurement, included air, paste density and mechanical strength and capillary water absorption tests. At the same time, mineralogical analysis techniques such as Fourier transform infrared spectroscopy (FTIR) were used. The mortars were characterised, by measuring a set of fundamental properties, including granulometric separation, consistency measurement, included air, paste density, mechanical strength tests and capillary water absorption. At the same time, mineralogical analysis techniques such as Fourier transform infrared spectroscopy (FTIR) were used. As for the tests required by the norms, and considering the mechanical resistance of the mortars, it was found that both the commercial mortars and those formulated (C1, R1, AA1 and AF1) are classified as CS II. Regarding the capillary water absorption test, it was found that only the formulation corresponding to the consolidation mortar (C1) showed a water absorption coefficient in line with the objective. This phenomenon suggested the presence of a water-repellent additive in the remaining mortars. Based on the obtained results, a study was conducted to determine the type and quantity of water-repellent (calcium stearate (CaE), sodium oleate (NaO), silane (Sil-A) and water-repellent resin (RH)) best suited to achieve the desired mortar properties. The results showed that silane is the best alternative for ensuring the long-term waterproofing of the lime mortars under study, with an excellent ability to reduce water absorption in amounts greater than 0.20 %. These results were confirmed by FTIR analysis, which showed that the pattern presented is very similar between the mortars, which, from the outset, suggests similar mineralogical compositions.
Description
Keywords
Mortar system Natural hidraulic lime Compressive strength Capillary water absorption Water-repellent additive Sistema de argamassas Cal hidráulica natural Resistência à compressão Absorção de água por capilaridade Aditivo hidrofugante