Concrete cancer is a serious issue that, if left undiagnosed and untreated, can affect the structural integrity of the building.

What triggers concrete cancer?

Concrete buildings are reinforced with bars or mesh made of steel during the construction process. Any exposure to air and water will lead to the formation of a weak carbonic acid, causing the steel to corrode. Being a porous material, concrete can easily absorb the elements around it including this acid. The corrosion forces the steel to expand, leading to cracks in the surrounding concrete. This condition, known as spalling, affects the strength of the building. The term ‘concrete cancer’ is used because the cracks further expose the steel to the elements, speeding up the level of corrosion, and the deterioration of the building. The vicious cycle of spalling impacts the building to such an extent that its structural integrity is seriously compromised.

Flat concrete roofs are particularly vulnerable to leaks and water-driven concrete cancer if they’re not adequately waterproofed.

Six common causes of concrete cancer include poor waterproofing, saltwater chlorides forming in buildings near the sea, building defects, weather, poor quality concrete and insufficient concrete cover, and ground movement under the build leading to cracks.

How to fix concrete cancer

If you have spotted signs of concrete cancer in your building, consult with a professional and get advice on the type of repair work required to be done. Early diagnosis and treatment will arrest further deterioration of the structure and save you money, which you may otherwise have to spend for ongoing repair work.

How to spot the signs

Concrete cancer can occur anytime so it’s a good idea to look out for tell-tale signs that your building may be affected. You can always call in a structural engineer to diagnose concrete cancer accurately.

Cracking or crumbling concrete or rust stains emerging from the concrete/ cement render are common signs. Also look out for bubbling concrete render and roof leaks, leaks in internal walls or concrete expanding outwards.

Diagnostic analysis of concrete cancer

Call in a professional for a detailed diagnosis of the problem. Have a qualified structural engineer conduct a diagnostic analysis – this is important because a repair contractor or repair materials supplier might not be adequately qualified or equipped to complete the job effectively. The engineer can identify the cause of the problem and prescribe the correct course of treatment.

Correct the problem

Depending on the cause of concrete cancer, your structural engineer might recommend different solutions.

1. Polymer modified repair system

Where concrete carbonation and low concrete cover have been identified as the issue, the engineer might recommend using a polymer modified repair system. This solution involves removing the concrete around the reinforcing bars and cleaning the steel, before applying both the steel primer and a polymer modified material. An anti-carbonation protective coating may also be applied to the whole concrete surface. Sometimes the experts might recommend using additional reinforcing steel anodes before new concrete is applied, or the steel might be replaced in severe cases.

2. Electrochemical treatment

If chloride contamination is the problem in buildings near the ocean, you might need to have specialist repair work done to treat the concrete cancer. This can include electrochemical treatment, such as cathodic protection.

3. Simple replacement

If the damage from concrete cancer is moderate, you might be able to remove the damaged concrete, clean and replace the rusted, exposed steel, and fill in the cracks.

Don’t miss the last step

Once the underlying steel and concrete have been repaired, you’ll need to cure it properly using specialist coatings. This is followed by the application of finishings, paints, and protective coatings as well as waterproofing.

Waterproofing as a preventative to concrete cancer

Once you’ve fixed the concrete cancer, take preventative steps to prevent a recurrence. Waterproofing the concrete is essential for preventing water or moisture from corroding the steel beams. Consider high quality options such as Wolfin or Cosmofin waterproofing membranes to seal the new horizontal concrete surfaces. This minimises the risk of future water damage, and prevents harsh chemicals contaminating the concrete from entering through pores. This is an important preventative because poor waterproofing, or worse, no waterproofing, could undo all the repair work on your building.

We want your concrete to be cancer-free

When it comes to concrete cancer, there’s no one-size-fits-all solution. The best repair option depends on your building materials and the extent of damage. Regardless of whether the damage is severe or moderate, waterproofing and comprehensive sealing after the repair is important to minimise the risk of concrete cancer in the building.

Projex Group has been a leading supplier of high quality engineering and waterproofing products for over 25 years.

Architecture & Design Team

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