Avaliação do comportamento de aderência entre blocos cerâmicos e grautes

Abstract

The behavior of structural masonry elements is influenced by the properties of the constituent materials and also by their interactions in the contact regions. The bonding properties between ceramic blocks and grouts used in masonry constitute a gap in national and international design standards. The existing knowledge in the academic world is currently insufficient to adequately describe the behavior presented by the interface of blocks and grouts. It is still unclear whether the grout is capable of adequately transferring the stresses of the reinforcement inserted into the masonry blocks. Thus, it is clear the need to deepen the studies developed to evaluate the adhesion properties between blocks and grouts. In this sense, the present study is inserted, aiming to expand the existing knowledge about the bonding behavior between ceramic blocks and grouts. In this sense, the present study is inserted, aiming to expand the existing knowledge about the bonding behavior between ceramic blocks and grouts. This research aimed to evaluate and discuss the properties that affect the adherence between 5 types of ceramic blocks and two types of grouts. The push-out test was used to evaluate the bond strength mobilized by the combination of these different materials. In addition, the pull-out test was also employed for some block types, seeking a more realistic analysis of the bonding behavior on masonry elements. The results obtained in the push test prove that there is a wide variation in the results, depending on the type of block and grout employed. Some of the main characteristics that influenced these results were the shape of the block cells and the shrinkage of the grout. The blocks that presented cells with more grooved surface and with friezes, tended to present increase in the contact area between grout and block, providing increases in the bonding stress. In the case of grout, the use of grout with higher compression resistance was responsible for the reduction in the results of the push test, precisely due to the reduction in the contact area caused by the shrinkage of the filler material. A test procedure was developed to analyze the shrinkage of the grout inside the ceramic blocks. Based on the results of the push test, an analytical model was developed considering two factors k1 and k2, responsible for considering the geometric shape of the block cell and the shrinkage of the filler material. This model allowed to roughly estimate which maximum load was mobilized in the push test for each combination of block type and grout. Finally, a numerical modeling of the identified interface properties was developed for two block types that presented grout slip during the push test. The behavior obtained was similar to that presented in the force vs sliding curves of the grout, for the tested specimens.