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

Abstract

AbstractCracking 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 ft, elastic modulus Ec, porous zone thickness δ0, corrosion current density icorr, critical chloride content Ccr, and chloride diffusion coefficient Dcl. 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 (ft↑, Ccr↑, Dcl↓, icorr↓) will induce increase of the service life, while the change of the others (Ec↑, δ0↓) 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.