Methodology for evaluation of the influence of roughness and capillary absorption of ceramic blocks on the render’s tensile bond strength

Abstract The literature indicates that it is difficult or even impossible to associate with strong statistical confidence the bond strength of a mortar coating with the properties of the ceramic block, such as roughness and water absorption. In this work, it is assumed that the variability in capillary water absorption and roughness, and the use of methods that provide differences in sampling area are key factors that make it difficult to model and obtain a proper correlation between these properties and the tensile bond strength of the render. Blocks with different porosities and roughness were used in the experimental program, and an original methodology was defined. Substrate properties showed high variability between blocks in the same batch, and in different regions of the same block. The proposed methodology allowed to obtain a significant correlation between substrate properties and the render’s tensile bond strength.