Análise da integridade de adesão de argamassas colantes em placas cerâmicas sob carregamento estático e dinâmico

Abstract

Despite the various technological advances achieved in the facade technology sector and the updating of normative documents that specify criteria for the use of cladding materials, it is still possible to see that a serious problem persists in modern constructions: ceramic detachment. The majority of these detachments occur at the interface between the adhesive mortar and the ceramic tile, as this is the region most stressed by simultaneous tensile and shearing efforts when considering the thermo-hygroscopic effects of the materials. Sudden temperature variations generate stresses that act on the adhesive mortar, leading to the appearance of damage through the action of thermomechanical fatigue. Despite this, in Brazil, the methodology adopted to evaluate adhesion in coatings consists of a test that only evaluates direct tensile strength. In this sense, this research aims to investigate the adhesion of mortar joints using destructive and non-destructive crack propagation tests, subjecting the samples to the combined action of tensile and shearing efforts. For this, sandwich-type samples were molded made up of two ceramic plates joined by adhesive mortar. The presence of cracks, in different sizes, was simulated at the mortar/ceramic interface. Two types of adhesive mortar were also used, differentiated by their adhesion capacity. The test results were analyzed according to load and energy parameters. The mixed-mode flexure test confirmed the importance of interface contact conditions on the fracture resistance of the material, pointing to an increase in the crack propagation speed the smaller the contact area of the materials. The use of the resonance technique proved to be efficient in identifying the presence of damage in samples, and guidelines for identifying damage based on the material's resonance response were established. The analysis of the resonance spectra made it possible to determine which were the regions of influence of the component materials and the representative peak of the effect of the crack on the mortar-ceramic interface. When comparing the two test methods, a good agreement between their results was observed and the critical energy required for crack propagation was established within the average of 0.056J±0.036J.