Concrete cancer in harbour infrastructure is one of the most common hidden issues we encounter at EP Marine & Rail.
Time and time again, we step onto structures that appear perfectly serviceable from the surface, only to discover a very different story once we begin assessing what is happening beneath and around the fixings, bolt systems and concrete foundations that hold critical marine assets together.
It is a powerful reminder that, in marine environments, what you can see is often only a small part of the picture.
What concrete cancer really is (and what it looks like on site)
Concrete cancer – formally known as spalling – is the deterioration of reinforced concrete caused by corrosion of internal steel reinforcement. We see it begin the same way almost every time.
Moisture finds its way into micro-cracks or porous concrete. Oxygen follows. Once both reach the steel reinforcement, corrosion begins. And then something quite dramatic happens inside the structure. The steel rusts and expands to several times its original size and that expansion creates internal pressure the concrete cannot resist.
So what we eventually see on the surface is:
- cracking
- flaking
- delamination
- sections of concrete breaking away entirely
But by the time this becomes visible, the internal damage is already well advanced.
Why we see this so often in marine environments
In marine infrastructure, concrete cancer is expected over time. The drivers we consistently see include:
Saltwater exposure
Chlorides penetrate concrete and accelerate corrosion once they reach reinforcement depth.
Poor or ageing concrete cover
In many older harbour structures, the steel reinforcement sits closer to the surface than it would in modern designs, which means saltwater and moisture can reach it sooner and accelerate corrosion.
Water ingress through joints and fixings
We often find failure starting around bolt groups, bollard bases, and interface points where water is repeatedly trapped.
Continuous wet–dry cycling
Unlike inland structures, marine assets rarely dry out fully, which keeps corrosion active once it begins.
What concrete cancer actually looks like in the field
On inspections, we often find early warning signs that are easy to dismiss if you are only doing a visual check:
- rust staining “bleeding” through concrete faces
- fine cracking radiating from bolt groups or bollard bases
- hollow-sounding concrete when tapped
- localised surface bulging or distortion
- coating failure caused by trapped moisture
Importantly, these signs are often concentrated around high-load transfer points, especially mooring bollards.
That is where the risk becomes critical.
Why bollards are one of the most vulnerable points
Rather than static structures, mooring bollards act as active load-transfer systems designed to manage immense maritime forces. When concrete cancer develops beneath these systems, the issue becomes structural.
We have seen cases where:
- internal reinforcement corrosion has reduced anchorage performance
- cracking has propagated beneath the visible surface with no external warning
- bolt groups have loosened due to hidden concrete degradation
- load distribution has shifted unevenly across the foundation
This is exactly why we focus heavily on advanced, NDT of bollard foundations, not just surface condition.
Real-world examples of this failure mechanism
This is not unique to one structure or region – concrete cancer is a well-documented global issue in marine infrastructure.
Marine bridge pier corrosion and spalling (China, 20+ year exposure)
A field study of a reinforced concrete bridge exposed to marine conditions found widespread cracking and spalling of pier structures after long-term chloride exposure, with reinforcement corrosion and loss of mechanical capacity.
Coastal quay wall corrosion and structural degradation (Polish ports)
Research on marine hydraulic structures identified advanced reinforcement corrosion in quay walls and breakwaters, particularly in splash and tidal zones, leading to significant concrete loss and structural weakening.
Mooring bollard failure due to corroded fixings (cargo barge incident)
A documented maritime safety incident showed a bollard toppling during loading operations due to severely corroded securing bolts, with failure only discovered under load conditions.
These examples all show the same underlying pattern:
The visible structure looked acceptable – until load or investigation revealed the true condition beneath.
Why visual inspection alone is not enough
We still carry out visual inspection as part of our process – but we never rely on it alone. The reason is simple:
Concrete cancer begins internally. And by the time it becomes visible, subsurface deterioration is already present. That is why marine structural integrity inspection must go far deeper than surface assessment.
At EP Marine & Rail, we use a combination of:
- ultrasonic bolt testing (to assess internal bolt condition and load path integrity)
- ground penetrating radar (to map subsurface voiding and reinforcement layout)
- eddy current testing (to detect surface-breaking and near-surface cracking in metallic components)
- specialist analysis software (to interpret structural response beneath fixings and load zones)
This allows us to see what is happening inside the structure and not just what appears on the outside of it.
What changes when you look below the surface
Once subsurface data is included, the picture changes quickly. We often find:
- deterioration beneath apparently “sound” concrete
- voiding around anchor zones
- corrosion initiating at reinforcement depth long before surface expression
- load transfer irregularities around bollard foundations
This is where marine structural integrity inspection becomes critical because it turns uncertainty into measurable condition data.
The real issue: delayed visibility, not sudden failure
Concrete cancer rarely fails suddenly. What actually happens is far more gradual:
- micro-cracking allows chloride ingress
- corrosion begins at reinforcement level
- expansion creates internal stress
- internal cracking spreads unseen
- surface spalling appears later
- structural capacity has already reduced
By step five, the structure is already compromised.
Final thought
At EP Marine & Rail, we’ve learned that the biggest risks in marine infrastructure are rarely the ones you can see. Every harbour, port and marine structure will age. The question is not whether deterioration exists, but whether it is being identified early enough to make informed decisions before safety, operations and budgets are affected.
That is why we use advanced, non-destructive testing methods to understand what is happening beneath the surface, around critical fixings and deep within the structures that keep ports and harbours operating safely every day.
Because when a vessel ties up alongside a berth, nobody is relying on what a bollard looks like. It is whether it is securely anchored, whether the surrounding concrete is still structurally sound, and whether hidden deterioration could cause it to loosen, fail, or be torn from its foundation under load.
While a bollard may look unchanged on the surface for many decades, once concrete cancer takes hold beneath it, the consequences can be sudden and severe.
These are the types of failures we help prevent.
And that is something surface inspections alone can never guarantee.