Ways to fix concrete cancer

23 May 2022
By Jeff Anderson

With all the rain in the last few months across the east coast of Australia (and by sad coincidence, the coast we offer our services too) there is a growing number of buildings with waterproofing issues and/or concrete cancer issues. Sometimes these issues are easy to spot with tell-tale signs instantly visible, but at other times, they are hidden away and only noticed through routine inspection, or luck.

But here’s the key thing to remember; once you find evidence of concrete spalling or concrete cancer, you need to act. This is because issues arising from concrete cancer have a tendency to affect the facade of a building aesthetically but in more serious cases, even affect the structural elements of the building itself. In other words, once you know it is an issue, it is important you fix concrete cancer immediately.

What to do once you notice Concrete Cancer

In the first instance you are going to need to engage an engineer to assess your building to ascertain not only where, but why and to what extent concrete cancer has affected the building. Hopefully, the damage is minimal, but often concrete cancer and spalling will affect multiple parts of a building at the same time due to the ingress of water and its tendency to track along elements to other areas.

With the problem ascertained, your engineer will deliver you a report that outlines the extent of the damage, the likely cause of the concrete cancer, and most importantly, a repair methodology that outlines what needs to be done and where on the building it needs to happen. This gives you a blueprint to come to a specialist repairs company like Remedial. Using a specialist is vital however, as a tradesperson will lack a number of key skills that you need (More on this below).

Typically, a remedial engineer will follow a standard procedure when providing you with a report:

  • Conduct a site visit to see the issues first-hand.
  • As necessary, tests to ascertain where the issues stem from.
  • Determine what is causing your concrete cancer and how many locations it is prevalent.
  • Evaluate how severe concrete cancer and/or spalling is within your building.
  • Develop a process to repair and/or rebuild the concrete structure to fix concrete cancer.
  • Make recommendations to the products or materials to use.

In many instances, once they have tabled this report to you, the Engineer may stay on as a consultant to you and organise to obtain quotes or tender submissions from capable remedial contractors.

Why you should use a qualified remedial contractor

I referenced above that you should be using a qualified remediation specialist for your rectification works. There are a number of reasons actually.

Type of Professional



Building/Construction Companies Access to Licenced Contractors
Knowledge of BCA, NCC AND Australian Standards
Can be Expensive
Lacking in Remedial Knowledge / Expertise
Not always interested in remediation
Project scale issues
Rarely have in-house engineering capability
Remedial Building Specialists Access to Licenced Contractors
Knowledge of BCA, NCC AND Australian Standards
HWI approval and coverage
Provision of PI Insurance
Knowledge of BCA, NCC AND Australian Standards
Engineering capabilities
Sometimes mistakenly perceived as expensive
Not always geared for small projects
Trades people Appears Cost Effective
Good at their field of expertise
Lack the depth of knowledge to apply meaningful remediation
Do not have HWI
Do not have PI insurance
Often apply solutions to cover the visible signs only, not the cause
Do not have HWI


The rationale for using a remedial contractor for building rectification work is based on the fact that remedial contractors are specialists in this type of work. Furthermore, a remedial specialist will:

  • Remove all evidence of affected concrete cancer.
  • Adhere to the scope of work provided by the engineer.
  • Expose all affected reinforcement and ensure its integrity.
  • Prepare and treat the existing steel reinforcement and concrete, or replace any steel that is too affected by rust and corrosion.
  • Implement solutions that prevent the recurrence of the issue.
    • Installation of drains, new slabs or more robust flashings as an example.
    • Apply waterproofing membranes or coatings to prevent water ingress.
    • Installation of suitable and approved concrete repair products.
    • Allow for proper curing of the repairs.
  • Maintain a methodical summary of all works undertaken for provision to the engineer.
  • Make-good: Returning the building to an as new (or better than new) standard.
    • This could be an upgrade to the facade through new textures, paints or protective coatings; or
    • Maybe a return of the facade to its pre-work appearance.
  • Document the location and details of the repaired areas.

In all cases of concrete cancer, steel corrosion is caused by water ingress into the concrete which reacts with the steel. As such, effective waterproofing is essential in preventing it from happening again. If you are after more information on the rectification of waterproofing issues our site is full of information.

Methodologies to fix Concrete Cancer

Once the damage caused by concrete cancer is accurately assessed, any one of the following processes may be used to fix concrete cancer:

Simple replacement.

If you catch the damage early enough, not only will you reduce your maintenance and rectification costs, but the work involved will be much less involved as well. It may be as simple as removing the affected concrete from the observed area, cleaning or replacing the affected steel elements, and replacing cracked and displaced concrete with a new mortar.

Electrochemical treatment.

If the engineer’s report identifies that chloride contamination is an area of concern (more likely for buildings near saltwater), then your remediation processes will likely include cathodic protection, a form of electrochemical treatment.

Polymer-modified, cement-based repair system.

Where concrete carbonation or poor construction methods (such as low concrete cover) have been identified as the issue, your engineers report may recommend the use of a polymer-modified repair system.

A polymer-modified solution requires the removal of affected concrete around the reinforcing bars and removal of all rust from the steel. A steel primer and a polymer-modified material are then applied to prevent further rusting from occuring. An anti-carbonation protective coating may also be applied to the exposed concrete surface.

Where the damage has been extensive, your engineer may recommend the installation of additional reinforcing steel anodes before new concrete is applied, or in extreme cases, the replacement of the structural steel entirely.

Specialist coatings and waterproofing.

Once the steel underneath is rectified can you start to work on prevention mechanisms. Whilst there may be many elements that caused the water to get in (from faulty windows to poorly installed flashings, to the degradation of existing solutions) a core consideration is the application of waterproofing coatings and membranes. These act to drain water to where it should go, prevent it getting to the slab and thus protect the structure from further damage.

With this done, you can then concentrate on the application of renders, paints, protective coatings, balustrades, tiles and so forth.


The one thing we want you to take away from this, is that you need to work to fix concrete caner. You cannot assume that treating the visible signs alone will be enough; in fact doing this is a recipe for disaster. We have seen too many examples of buildings that have had coats of paint and render repair applied without fixing root cause. If you would like to discuss the issues plaguing your building – whether you have an engineers report yet or not – then let’s have a chat.