Chloride Diffusion-Convection into Unsaturated RC Hollow Cylinder Piles in Marine Tidal Zones

Abstract

Chloride penetration into reinforced concrete (RC) hollow cylinder piles has been identified as one of major factors to cause corrosion of reinforcing steel and to affect the performance and serviceability of piles. Chloride penetration into unsaturated RC hollow cylinder piles in marine tidal zones involves the coupling of diffusion and convection mechanisms. The goal of this study is to investigate the chloride diffusion-convection behavior into unsaturated RC hollow cylinder piles in marine tidal zones through numerical modeling. The governing equation to model the chloride diffusion-convection mechanism was derived and solved numerically using the finite difference method. An illustrative example was demonstrated to predict the chloride concentration distributions in unsaturated RC hollow cylinder piles in the marine tidal zones. Parametric analysis was performed to examine the influence of the main parameters on the chloride concentration distributions in unsaturated RC hollow cylinder piles. The analysis results indicated that the convection action had an obvious effect on the chloride penetration in the convection zone. Chloride diffusion-convection resulted in an increase in the chloride concentration, and the increase in the convection zone was more significant compared to that in the steady diffusion zone at a fixed exposure depth. The influence of the convection zone depth on the chloride concentration distributions was not as significant as the effects of chloride diffusion coefficient and convection velocity in unsaturated RC hollow cylinder piles.