Influência da Diatomita nas propriedades de argamassa à base de cal para restauro

Abstract

In recent years, the demand for conservation and rehabilitation services in historic buildings has increased. This is necessary, as preserving historic buildings is an important step in safeguarding a people's culture, identity and memories as a alive document. These interventions are often carried out with changes to materials and construction processes that have not always contributed to improving the state of conservation of historic buildings. With the main objective of evaluating the influence of diatomite on the physical, chemical and mechanical properties of lime-based mortars for the restoration of historic buildings, 4 (four) lime and sand-based mortar mixes (1:2, 1:4, 1:6 and 1:8) were selected, which are the most commonly found in historic buildings around the world. Diatomite was then incorporated, replacing hydrated lime in mass percentages of 10% and 20% in each of these four reference mixtures. The physical-mechanical characterization of the restoration mortar specimens was carried out at 28 and 90 days of age The results of the tests performed show an increase in the mechanical performance of the mortars with the incorporation of diatomite, reaching an average increase of 2.2 times in the axial compression resistance when 20% of diatomite was incorporated. Tests were also carried out with phenolphthalein at 150 days of age, revealing total carbonation of the samples in the reference traces Ref. - 1:8 and T20% - 1:8. Finishing the tests with durability assessment in 2 (two) scenarios, the first scenario being the test specimens exposed to 10 (ten) wetting/drying cycles with a saline solution (water + NaCl) and another with only drinking water (free of salts). The results of the analysis of the test specimens in saline solution showed surface wear from the mixtures with a binder-aggregate ratio of 1:6 onwards, both in the mortar samples without diatomite and in the samples with diatomite. Being the mix with the greatest surface damage and mass loss, the reference mix 1:8 followed by the mix 1:8 with 20% diatomite. In the scenario of immersion cycles in saltfree water, there was no aesthetic damage to the samples, nor was there any wear causing significant mass loss. Therefore, it can be concluded that the incorporation of diatomite brought gains in mechanical performance, but did not influence the increase in durability.