Treating Concrete Cancer

Have you heard of concrete cancer repairs? Do you know what it is and why it deserves your attention?

In this article, we’ll answer everything you need to know about what concrete cancer is, why it’s a problem, how to recognise its signs and how to treat it as effectively as possible.

Concrete Cancer – what is it?

Concrete may be one of the more versatile and durable materials used in construction but that doesn’t mean it is completely impervious to damage. On the most common and concerning issues related to concrete is what is commonly dubbed “concrete cancer”. 

Essentially, concrete cancer – also called concrete spalling or decay – is the term used to describe reinforced concrete structures deteriorating due to the corrosion of the steel reinforcement bars embedded within the very concrete itself. When these steel bars corrode they begin to crack, flake and become weaker and weaker over time. 

Unfortunately concrete cancer repair could be required in just about any type of structure that uses concrete, including bridges, buildings, parking garages and more.

Why repairing concrete cancer is important


Structural integrity

When the steel bars within the concrete corrode and weaken they begin to expand. This expansion causes the concrete itself to begin to crack and spall. If this damage gets too extensive the structural integrity of the structure could be at risk.


Visible signs of concrete cancer can be unsightly to occupants and potential property owners. Even in instances where there are no concerns about the structural integrity of the building, it can cause undue worry amongst users and visitors.


Concrete cancer can severely impact and diminish the value of a property if you should try and re-sell it. The longer you leave the cancer, the worse the repairs and the more extensive (read: costly) the treatment.


On this note, maintenance costs for repairing concrete cancer can be extensive as is. The longer it is left untreated the more extensive the damage, the more likely additional accidents are going to take place, and the greater the risk.


Most importantly, not arranging concrete cancer repair can pose a risk to the people and property in, around and below it. Timely treatment and servicing is crucial to ensure that the building is up to safety code and expectations. 

How to recognise concrete cancer


1. Cracks

While cracks may not always be the result of concrete cancer, they can be a clear indicator. Especially when they appear with rust stains and/or exposed rebar.

2. Spalling

If you notice flaking or chipping on the surface of your concrete it could be caused by the steel bars corroding within.

3. Rust stains

Rust stains on the surface of the concrete and/or along the cracks are a telltale sign of rebar corrosion.

4. Damage

Other forms of damage, such as bulging or blistering, which can make the concrete itself seem like it’s swollen or reddening can indicate internal pressure from within that is consistent with corroding rebar.

5. Hollow sounds

If you tap the concrete with a hard object, such as a mallet, listen for dull or hollow sounds. This can indicate an internal void caused by deteriorating concrete.

How to repair concrete cancer


Step 1: Arrange an Inspection

Getting a professional opinion is important. The official assessment will include a comprehensive review of the extent of the damage through visual inspection, non-destructive testing and, if required, core sampling. 

Step 2: Identify Cause

Once the damage has been assessed, the surface will be prepared for a more indepth cause identification process. The cause of the corrosion, such as moisture exposure, or presence of other corrosive substances needs to be addressed for effective concrete cancer repair.

Step 3: Surface Preparation

The rebar itself needs to be exposed. Using hand tools or machinery the loose material and deteriorated concrete around the rebar will be removed.

Step 4: Rebar Repair

The internal steel beams will need to be cleaned and freed from rust using specialised wire brushes and similar tools. Ideally, a corrosion inhibitor will be applied to provide a protective coating that can prevent further or recurring corrosion.

Step 5: Patching

The motor needs to be reapplied, including the filling of voids and required attention to damaged areas, before the upper layers of concrete are patched over. A smooth and finished upper surface that matches the surrounding concrete is then applied.

Step 6: Protective Coating

To help prevent further concrete cancer, protective coatings and sealants are generally used. 

Ongoing Maintenance


As we have reiterated a few times, early detection and treatment of concrete cancer is the best way to minimise the likelihood of extensive and costly repairs.

Regular inspections, independently and by professionals, will help you catch and identify issues before they spiral out of hand.

Fortunately, addressing concrete cancer repair promptly can effectively curb the worse and more extensive of the potential damage. 

For concrete cancer repairs, call the concrete doctors at BIM Sydney

At BIM Sydney, our team are specialists in remedial building maintenance services, including concrete cancer and related damage. From spalling concrete to slab levelling, and from carbon fibre strengthening to external waterproofing, we can and have done it all!

Whether you’re not sure what sort of damage has occurred to your building’s concrete or you need a professional to apply some urgent concrete cancer repair work, give the BIM Sydney office a call today.

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