Probabilistic Modelling of Marine Bridge Deterioration

Chloride induced corrosion of steel reinforcement is the main cause of deterioration of reinforced concrete marine structures. This paper investigates the relative performance of alternative repair options with respect to the deterioration of reinforced concrete bridge elements in marine environments. Focus is placed on the initiation phase of reinforcement corrosion. A laboratory study is described which involved exposing concrete samples to accelerated chloride-ion ingress. The study examined the relative efficiencies of two repair methods, namely Ordinary Portland Cement (OPC) concrete and a concrete which utilised Ground Granulated Blastfurnace Cement (GGBS) as a partial cement replacement. The mix designs and materials utilised were identical to those implemented in the repair of a marine bridge on the South East coast of Ireland in 2007. The results of this testing regime serve to inform input variables employed in probabilistic modelling of deterioration for subsequent reliability based analysis to compare the relative performance of the studied repair options. Keywords—Deterioration, Marine Bridges, Reinforced Concrete, Reliability, Chloride-ion Ingress List of Abbreviations Ccrit Critical Chloride Content CoV Coefficient of Variation Dapp Apparent diffusion coefficient GGBS Ground Granulated Blastfurnace Slag OPC Ordinary Portland Cement PDF Probability Density Function RC Reinforced Concrete TCD Trinity College Dublin Ti Time to initiation of corrosion