What is Concrete Spalling (Cancer) and What Causes It?

The concrete used in buildings is reinforced with steel and iron bars or mesh. When exposed to air and water (such as through leaks) a weak carbonic acid starts to form and the reinforcement begin to corrode. Concrete is a porous material and can easily absorb the elements around it – including this corroding acid. Once corrosion starts, the steel expands, causing the surrounding concrete to crack, known as spalling.

The term ‘cancer’ is used because of the 'vicious cycle' nature of the corrosion. The cracks further expose the steel to the elements, which speeds up the level of corrosion, advancing the problem further and faster.

The impact on the building leads to a tragic compromise of structural integrity.

Six common causes of concrete cancer include:

1. Poor Waterproofing - Buildings that have not been waterproofed, or have been poorly waterproofed, are likely to suffer from concrete cancer as they do not have the sufficient protection in place.
2. Salt-water chlorides for buildings near the sea - For buildings near the ocean, chlorides from salt water can enter the concrete, even after it is built, and corrode the steel.
3. Building defects - Corrosion occurs when a building has defects which leave the concrete and the supporting steel vulnerable.
4. Weather - Concrete in colder climates is especially vulnerable, as the freeze-thawing of water can enlarge concrete pores much quicker, allowing the water to easily enter the concrete.
5. Poor quality concrete and insufficient concrete cover - Defects such as cracking, poor quality concrete or depth of concrete all increase the ability for water and air to corrode the reinforcement 
6. Movement of the earth under the build leading to cracks - The natural movement of the earth underneath the building can cause natural cracks which exposes the steel to the elements, and can also allow water to enter the building from the ground.

How to Spot Concrete Spalling (Cancer):

If you suspect your building has been affected by concrete cancer, make sure you get it checked by a professional (such as an engineer, remedial builder or waterproofing contractor) so you know what type of repair work has to be done. The earlier you catch it and have it fixed, the more likely you can avoid paying more for repairs than you have to.

Most structural engineers will be able to spot concrete cancer before you can. However, they’re not always on hand, so it pays to know the tell-tale signs that it may be time to get in the experts:

• Cracking or crumbling concrete
• Rust stains that seem to come out from the concrete
• The concrete render starts to bubble
• Roof leaks or any that appear in internal walls

While people often mistake these signs as general wear and tear, they can be signs of something much more sinister.

What can be done about it and how can such problems be prevented in the first place?

Waterproofing is perhaps the best way to prevent concrete cancer so invest in good quality waterproofing membranes to help minimise the chances of water leakage. Keeping an eye on your structures is also wise so that you can spot standing water issues immediately and have them fixed before they become problematic. Do the same for internal leaks as well.

If you see a crack anywhere, deal with it straightaway. You should also have the concrete sealed on a regular basis to protect against water damage and wear and tear. Painting your concrete can also help to protect it over time.

When it comes to concrete repairs, make sure you seek out a professional opinion from a reputable company. It could be very costly to do otherwise and you may not end up with a long-term solution to your problem. If you’d like to find out more, contact us today.