%0 Journal Article
%T Approaches for Modelling the Residual Service Life of Marine Concrete Structures
%A Amir Rahimi
%A Christoph Gehlen
%A Thorsten Reschke
%A Andreas Westendarp
%J International Journal of Corrosion
%D 2014
%I Hindawi Publishing Corporation
%R 10.1155/2014/432472
%X This paper deals with the service life design of existing reinforced concrete structures in a marine environment. The general procedure of condition assessment for estimating the residual service life of structures before a repair measure is illustrated. For assessment of the residual service life of structures which have undergone a repair measure a simplified mathematical model of chloride diffusion in a 2-layer system is presented. Preliminary probabilistic calculations demonstrate the effect of various conditions on the residual service life. First studies of the chloride diffusion in a 2-layer system have been conducted using the finite element method. Results of a long-term exposure test are presented to illustrate the performance of two different repair materials. The distribution of residual chlorides after application of a repair material is being studied in laboratory investigations. The residual chlorides migrate from the concrete layer into the new layer immediately after the repair material has been applied to the concrete member. The content and gradient of residual chlorides, along with the thickness and the chloride ingress resistance of both the remaining and the new layer of cover, will determine the residual service life of the repaired structures. 1. Introduction Concrete structures in a marine environment such as locks, dams and bridges are affected by a wide range of degradation phenomena. Chloride-induced corrosion is the decisive aspect in the durability of such structures. Reinforcement corrosion is initiated when a critical chloride content is reached at the surface of the rebars. Chloride contents higher than the critical value can cause disruption of the protective passive layer, leading to corrosion of the rebars. The time required to initiate corrosion depends, apart from some environmental factors, on the properties of the concrete, in particular on its resistance to chloride diffusion. The following period, the propagation period, refers to the evolution of different forms of deterioration after corrosion has been initiated (cracking, spalling, loss of bond between rebars, and concrete and reduction in the rebar cross-section). Although the service life of structures is the sum of these two periods, in most cases the initiation period defines the service life because the propagation period may be very short. A traditional and feasible repair method consists of removing the chloride-contaminated concrete layer and replacing the removed volume by cement-based repair mortars or concretes. The aim of this measure is either to
%U http://www.hindawi.com/journals/ijc/2014/432472/