Rejuvenating Aging Port Infrastructure

1. Rejuvenating Aging Port Infrastructure Australia’s port infrastructure facilitates $213 (billion) per annum in total trade. Port infrastructure is primarily constructed of reinforced concrete (RC) and is exposed to a corrosive marine environment. However, maritime infrastructure is vulnerable to deterioration due to the corrosive influence of salt-laden waves and sea air. Deterioration leads to loss of functionality, delays in shipping caused by maintenance and remediation works, and in the worst cases, loss of structural integrity (leading to risks of injury to workers, reduced operation of the facility and consequent asset replacement. Monash University has been actively contributing towards sustaining aging built port infrastructure by conducting research on predictive modelling of deterioration and methods of controlling corrosion. Expansive corrosion of embedded steel reinforcement has led to a major longitudinal crack along the soffit of a crosshead beam Corrosion damage beneath a major port structure, resulting in detachment of the surface concrete and losses of steel Swanson Dock, Australia’s Largest Container Terminal The splash zone exposure environment is a particularly corrosive microclimate underneath a port structure PROJECTS(supported by Australian Research Council (ARC) LP0883290 and LP0776702, and Monash internal research grants) Contact: Dr Frank Collins, Department of Civil Engineering Within most structures, concrete normally has a high pH (≈ 12.5) due to hydration of the cement constituents during concrete mixing. The high pH is conducive to the embedded steel forming a passive oxide film which minimizes corrosion. In a marine environment, chlorides from seawater and airborne spray accumulate on the concrete surface and, over time, diffuse into the concrete. When the concentration of chloride at the steel depth exceeds a threshold concentration, the passive oxide film converts into other oxides that occupy a significantly greater volume than the parent steel: the resulting expansion leads to tensile stresses within the outer cover zone of concrete, leading to crack and detachment of the concrete. In the worst cases, the detachment of concrete and losses of steel area caused by corrosion can reduce the structural capacity of the structural member. 3D MODELLING OF DAMAGE DUE TO STEEL REINFORCEMENT CORROSION ADVANCED PREDICTIVE MODELLING  PROACTIVE APPROACH TO ASSET MANAGEMENT Existing predictive models are based on 1D or 2D applications. However these models are limited due to non-consideration of 3 dimensional aspects, such as: materials, the geometry and location of embedded Reinforcing steel, and the aspect and location of the exposed concrete to the external environment. The key predictive modelling aspects include “Time to corrosion initiation” based on diffusion theory, followed by incorporation of the “Propagation Stage” and the “Time to damage” Including crack propagation, loss of steel to concrete bond, loss of steel section), and structural capacity. Cooperation with major Australian ports has lead to access of historical condition data for analysis. A user-friendly, real-time, 3D deterioration model is being developed that will enable an asset manager with appropriate knowledge and experience to use.A 3D visual aspect to the prediction tool will be a key model output. This will allow both technical and non-technical users to review and optimise the ongoing maintenance of the asset. Once the “base-line” geometry of a port structure geometry has been established, the 3D prediction tool will be utilised to forecast the growth of deterioration of the structure and developed into a prediction animation that graphically demonstrates the future condition over the remaining service life of the asset, allowing asset managers to review and optimise the ongoing maintenance. Thin passive iron oxide layer forms on the steel pH ≈ 12.5 Corrosion Damage 3D Damage Simulation by Finite Element Modelling