Effect of water‐to‐cement ratio on service life of reinforced concrete structures in chloride environment

Abstract

Abstract Cracking of concrete induced by rebar corrosion is a main cause for deterioration of reinforced concrete structures especially for those exposed to chloride environment. In all of the parameters influencing the service life of concrete structures, water‐to‐cement ratio is a very important one for it determines the resistance of concrete against chloride aggression and corrosion‐induced damage. In this paper, the parameters in corrosion process influenced by water‐to‐cement ratio of concrete ( w / c ) are screened all‐round which include concrete tensile strength f t , elastic modulus E c , porous zone thickness δ 0 , corrosion current density i corr , critical chloride content C cr , and chloride diffusion coefficient D cl . The influences of w / c on the chloride penetration stage and the corrosion damage stage are studied. The first stage is expressed by Fick's second law, and the second stage is calculated using a commonly used analytical model, i.e. the thick‐walled cylinder model. It is found that with the increase of w / c , the change of some parameters ( f t ↑, C cr ↑, D cl ↓, i corr ↓) will induce increase of the service life, while the change of the others ( E c ↑, δ 0 ↓) will induce decrease of the service life. The diffusion stage and damage stage both shorten with the increase of w / c , and thus the total service life decreases with the increase of w / c . These results show that the increase of w / c presents a negative effect on the service life of concrete structures in total. In addition, with the increase of w / c , the service life for various concrete cover thicknesses and rebar diameters decrease in a similar tendency. For probability analyses, it is found that the probability density curves under different w / c are almost symmetric but show a little left‐skewed, and the total service life for various w / c fluctuates about 0.6 to 1.0 year.

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