Study of concrete cracking during accelerated corrosion tests in reinforced concrete

摘要

Cracking of reinforced concrete can occur in certain environments due to rebar corrosion.udThe oxide layer growing around the bars introduces a pressure which may be enough to lead to theudfracture of concrete. To study such an effect, the results of accelerated corrosion tests and finite ele-udment simulations are combined in this work. In previous works, a numerical model for the expansiveudlayer, calledudexpansive joint elementud, was programmed by the authors to reproduce the effect of theudoxide over the concrete. In that model, the expansion of the oxide layer in stress free conditions isudsimulated as an uniform expansion perpendicular to the steel surface. The cracking of concrete isudsimulated by means of finite elements with an embedded adaptable cohesive crack that follow theudstandard cohesive model. In the present work, further accelerated tests with imposed constant cur-udrent have been carried out on the same type of specimens tested in previous works (with an embeddedudsteel tube), while measuring, among other things, the main-crack mouth opening. Then, the tests haveudbeen numerically simulated using the expansive joint element and the tube as the corroding electrodeud(rather than a bar). As a result of the comparison of numerical and experimental results, both forudthe crack mouth opening and the crack pattern, new insight is gained into the behavior of the oxideudlayer. In particular, quantitative assessment of the oxide expansion relation is deduced from the ex-udperiments, and a narrower interval for the shear stiffness of the oxide layer is obtained, which couldudnot be achieved using bars as the corroding element, because in that case the numerical results wereudinsensitive to the shear stiffness of the oxide layer within many orders of magnitude