Análise de aderência de diferentes argamassas para revestimento através de métodos distintos de ensaio

Abstract

The first researches with paste-bearing mortars in Brazil date back to the 1960s, motivated by coverings detachments. The mortar detachment is directly attached to the adherence property of this material. The technological control of this property is performed by the tensile bond strength test, prescribed by NBR 13528 (ABNT, 2010). However, the equipment prescribed by the standard for this test has a high acquisition cost. In this work, we propose the performance analysis of a developed equipment of lower cost, and of simple operation and handling, for the qualitative control in current works and of smaller size. For this, a tensile bond strength test was carried out in a work located in the city of Toledo, in which four panels of mortar covering were produced, distinguished by the trace (cement or mixed) and by the number of layers (with or without roughcast). By way of comparison, the test was performed both with the equipment proposed by the standard and with the equipment developed. However, for the equipment prescribed by the standard, the pulling of the sample is obtained by axial tensile tension, for the developed equipment this pullout is performed by the lever principle. The results showed that mixed mortars had an average adherence resistance about 50% lower than cement based mortars. However, the mixed mortar panel presented higher adherence strength when accompanied by a layer of roughcast, thus showing the importance of this layer for the adherence of the covering to the substrate. Regarding the equipment developed, there was no direct correlation with the equipment proposed by the standard, possibly due to the difference in the method of pulling the samples. The resistance values determined with the developed equipment were, on average, lower than the equipment prescribed by the standard in all tests.