Estudo de tirantes produzidos com concreto autoadensável moldado na vertical e horizontal

Abstract

This research had the objective to analyze the stress transfer mechanism in specimens under tension, through the self-compacting concrete cracking process, casted on normal and perpendicular directions to the rebar. In order to attain the objectives, cylindrical specimens were casted with the aim to assess the behavior under axial compression stress and the prismatic specimens were submitted to tests in order to evaluate behavior under tensile stress. The specimens have dimensions of 15x15x75cm and were casted on the vertical and horizontal positions using 20 and 25mm rebar, passing through the center of the square section (15x15cm). The assessment of the process was done through the use of image correlation. Computerized tomography was used to evaluate the void dispersion in the specimens casted in different directions. For the casting of specimens, a self-compacting 65MPa strength concrete was utilized. For the characterization of flow, plastic viscosity and flowability in the fresh state, rheological tests were made using Abrams cone with and without the “J” ring, “V” funnel and “L” box. The results found were convenient for the characteristics of the used concrete. It was observed that the specimen’s results presented differences in their fracture mechanism. The specimens casted on the horizontal direction due to failure in adherence yielded asynchronous cracking on their faces, meaning the cracking did not pass through the cross section. However, for specimens casted on the vertical the cracking appeared simultaneously, that is, they pass through the cross section.