Estudo da aderência entre concreto e argamassas

Abstract

The current focus on sustainable development emphasizes the repair and reinforcement of concrete structures rather than new ones. At this point, concrete repairs need to be as long-lasting as possible. One of the critical issues of concrete repair durability is an effective and lasting bond between the repair material and the existing concrete substrate. This paper discourses an experimental program conducted to evaluate the bond strength between concrete and mortars. Eight types of mortars were tested, half comercial products specific for repairs, which two were cementitious mortars and two polymeric, one mortar produced in the laboratory and three kinds of fiber reinforced cementitious composites. The main tests carried out were the slant shear test, according to the current British standard and the pull off test, according to European and Brazilian standards. In the slant shear test, the prismatic specimens had dimensions of 100x100x400 mm and interface with an angle of 60º to the cross-sectional axis. To represent the bond, a conventional concrete was used as existing substrate. The only kind of roughness considered for interface surface was grooves, obtained by using a mechanical tool. The repair materials were applied in fresh condition to the hardened substrate without bonding agent. The test specimens were tested 28 days after pouring the mortars. The technical literature review has shown that the slant shear test is the most widely used to analyze the bond between concretes. With this study, it was possible to qualitatively evaluate the results and display that all ready to use mortars had better performance.