Análise quantitativa da influência da rugosidade e da área de interface entre substratos cerâmicos e revestimento cimentício na resistência de aderência à tração

Abstract

The sealing system adopted in Brazil, traditionally, consists of ceramic blocks and mortar renderings. The property that relates the junction between the substrate and the mortar is adhesion. Ceramic blocks are characterized according to their porosity, surface roughness and capillary suction, depending on the composition of the raw material, the process and the sintering temperature used in their production. Mortars are multiphase materials, composed of particles with different granulometric distributions, homogenized in the fresh state and which in the hardened state will result in volumetric changes, including the cement hydration products. In this sense, the main objective is the quantitative analysis of the influence of roughness and interface area between ceramic substrates and cementitious coating on the tensile bond strength. Thus, it was proposed to work with a single cement paste, apply it on five ceramic blocks with different roughness and thus quantify the adhesion of the paste in different topographies of substrates and correlate the interface area between the substrates and the Portland cement paste. . The ceramic blocks were characterized for roughness using 3D methods by laser profilometry and photogrammetry. In this research, roughness parameters that showed a significant interference in the adhesion between the ceramic block and the cement matrix were quantified. The heterogeneity of the ceramic substrate implies that when the tensile strength between a cementitious matrix and the substrate is determined in a smaller area, less variability and greater strength is obtained than when it is determined in a larger area. Roughness has a great influence on the tensile bond strength, which is also influenced by other factors that overlap. A multiple linear regression, determined from different ceramic substrates, when used for the individual analysis of each substrate, cannot estimate adhesion results with a significant coefficient of determination. However, it is possible to relate a roughness matrix, correlating the average height of the valleys (Rvm) and the average roughness (Ra), with the respective average areas of the valleys (Amv) of the substrate and with the average tensile bond strengths.