Probabilistic modeling of reinforced concrete bridge repair deterioration in marine environments

This paper presents the results of an extensive experimental study performed to identify the characteristics of deterioration of a repaired concrete bridge located in a Marine environment in the south east of Ireland. A probability based deterioration model is presented with the parameters of the model discussed. The model is calibrated using the results of accelerated chloride ion ingress tests carried out in a salt (fog) spray chamber at Trinity College Dublin. The testing involved exposing concrete samples, constructed using five different repair options, to cyclic salt spray mist and drying. After eight months of exposure the samples were analyzed to investigate the relative merits of the various repair materials in resisting chloride ion ingress. The repair alternatives investigated were; Ordinary Portland Cement (OPC), OPC with Ground Granulated Blastfurnace Slag (GGBS) as a partial cement replacement, OPC with Pulverized Fuel Ash (PFA) as a partial cement replacement, OPC with a silane treatment applied and OPC with increased cover. The paper presents the details and findings of the laboratory experiments. The probability based deterioration model is utilized to study the relative merits of the various repair materials in real terms, i.e. with respect to predicted time to initiation of corrosion. This allows the efficiencies of the repair materials in the initiation phase of corrosion to be considered in a robust stochastic manner.