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.
Swanson Dock, Australia’s Largest Container Terminal
The splash zone exposure environment is a
particularly corrosive microclimate underneath
a port structure
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
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
Existing predictive models are based on 1D or 2D applications. Howe
ver these models are limited due to non-consideration of 3 dimension
al
aspects, such as: materials, the geometry and location of embedded
Reinforcing steel, and the aspect and location of the exposed concret
e
to the external environment. The key predictive modelling aspects
include “Time to corrosion initiation” based on diffusion theory, followe
d by incorporation of the “Propagation Stage” and the “Time to dama
ge”
Including crack propagation, loss of steel to concrete bond, loss of st
eel section), and structural capacity.
Thin passive iron
oxide layer forms
on the steel
pH ≈ 12.5
Corrosion Damage
3D Damage Simulation
by
Finite
Element
Modelling
ADVANCED PREDICTIVE MODELLING
 PROACTIVE APPROACH TO ASSET MANAGEMENT
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 “baseline” 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.