Avaliação do ensaio Barcelona como controle tecnológico do concreto reforçado com fibras de aço

Abstract

Concrete structures require reliable, economic and, preferably, simple execution methods. In case of fiber-reinforced concretes (FRC), this control is based on tenacity and residual resistances, usually obtained from beam flexural tests, being the Japanese test JSCE-SF4 the most commonly used in Brazil due to the lack of a norm of technological control specific to this type of concrete in the country. These tests, however, require large specimens and specific equipment rarely found in conventional laboratories and have reliability problems due to the high coefficients of variation (on average 20%) commonly observed between trials. In this context, the Barcelona test emerges as a promising and reliable alternative in the evaluation of the main parameters of the CRF, as it uses cylindrical specimens and equipment that is easily accessible in most laboratories. In the present work, three grades of 80 form factor steel fibers (0,0%, 0,5% and 1,0%) were submitted to the Barcelona test in order to analyze the influence of the fibers on the toughness of the concrete and the accuracy of this test when compared to the flexural tests. It was also analyzed the influence that the addition of fibers to the concrete causes in the compressive and the tensile strengths. It was verified that, although they did not influence much in both the compressive and tensile strengths, the fibers proved to be very effective in increasing the concrete's toughness, provoking a post-rupture behavior, with the appearance of residual resistances that prevent abrupt rupture of the concrete even after reaching the peak load. The coefficients of variation obtained in the Barcelona test were between 7% and 13%, values well below those commonly observed in flexural tests, indicating a good reproducibility and precision of this test and proving its feasibility of execution as a technological control of the reinforced concrete with fibers of steel.