Avaliação do comportamento de revestimento de argamassa submetido a envelhecimento acelerado e à carbonatação

Abstract

The continuous wetting and drying cycles to which mortar coatings are subjected throughout their life, associated with the effect of carbonation and the impacts arising from use, cause traction and shear stresses to the coating that, throughout its useful life, may cause microcracks in the structure of the coating and, therefore, influence the way the material ruptures. Consequently, it is recommended to give mortars a low modulus of elasticity, which is responsible for their ability to deform without cracking when subjected to stress. However, this property is affected by the aging process and carbonation, which can make the mortar more rigid or more elastic. The objective of this research is to evaluate the effect of carbonation and accelerated aging on the behavior of the mortar when subjected to tensile stress, when applied on different substrates, as well as to estimate the modulus of elasticity by digital image correlation (CID). Two ceramic substrates with different capillary absorption and roughness values were used. Mortars were molded in the proportion 1:1:4 (cement:lime:sand), CP II-F 40 and lime CH-I, a/gl ratio 0.80. Samples were cured for 56 days in a controlled environment. The voids index, water absorption by capillarity and tensile strength were determined before and after the aging and carbonation processes. The stress and deformation analysis was carried out applying the CID methodology and later calculating the modulus of elasticity with the aid of specific software. It was concluded that accelerated aging increases capillary water absorption and reduces bond strength and that carbonation is influenced by the type of substrate to which the mortar is applied. The modulus of elasticity calculated from the CID were coherent with the values found in the literature and indicated that there are modulus differences along the thickness of the coating.