Contribuição ao estudo da influência da área de contato na aderência da interface argamassa colante-cerâmica.

Abstract

The detachment of ceramic tiles in buildings is a problem that still persists in several modern buildings, despite the various advances achieved in the sector of façade technology and an increasingly demanding consumer public. Such detachments may occur by adhesive rupture at the interfaces of the system or by cohesive rupture within any of its layers. Studies have shown that most ceramic façades in facades occur in the interface mortar and ceramic plaque and this is because it is the region of the most requested coating system by shear stresses. In Brazil, the most used methodology to evaluate the adhesion of ceramic coatings is the adhesion strength test to direct traction, however, such evaluation may be insufficient to verify the adhesion quality of the coatings to the substrate, since the adherence of the system is resulting not only from the tensile strength, but also from the shear bond strength and the extent of adhesion of the mortar. This dissertation aims to contribute to the study and understanding of the influence of the contact area on the adhesion of the interface between adhesive mortar and ceramic plate by means of the evaluation of the adhesion resistance from the crack propagation test in mixed mode of stress (MMF - Mixed Mode Flexure) simulates tensile and shear forces simultaneously. The systems produced in the laboratory reproduce conditions where the failure in the extension of the mortar contributes to the decrease of the resistance of adhesion. Through a universal mechanical testing machine, a punctual progressive load was applied to the 120 specimens produced in order to promote internal tensile and shear forces. The variables incorporated into the experiment were the type of mortar used, the thickness of the mortar in the specimen and the size of the glue failure induced in the set. The experimental results show that the adhesion strength at the interface between the adhesive mortar and the ceramic plate decreases as the adhesion failure increases, with a loss of adhesion of up to 44.2% and 51.4% (AC II and AC III, respectively). The adhesion strength values found by the direct drive test were 60.8% (AC II) and 58.1% (AC III) higher than the results obtained by the mechanical test in mixed mode, indicating an oversized system result of the facade cladding when the direct tensile adhesion strength was verified alone.