Remedial Services
December 2nd, 2021

How to treat Concrete Cancer and Efflorescence

Concrete cancer can cause significant structural damage, while efflorescence can negatively impact your strata’s appearance. These can work to negatively impact the overall value of your site.

Which buildings are most at risk?

Unfortunately, not all buildings are considered equal, with some more at risk than others. Older buildings (built before 1997) are more likely to be affected by concrete cancer. Despite there being an increase in requirements and specification surrounding concrete strength and coverage, newer buildings are not exempt from this phenomenon.

Concrete cancer can be accelerated by salt spray and moisture. Given 85% of the Australian population live near the coast, there is a high likelihood of susceptibility for many properties.

Efflorescence, or mottling, can form in cement-based products like bricks, mortar and sometimes concrete. It appears as a powdery white, yellow or brown substance and occurs through excess water seeping through the exterior masonry walls. Failing to adequately prepare surfaces by removing all previous efflorescence causes insufficient surface preservation. Despite being harmless, efflorescence sends the message of poor maintenance and can reduce the overall value of your property.  

How can Concrete Cancer be treated?

Concrete cancer is a more severe phenomenon than mottling. If detected early, it is much easier to treat. As a result, an effective strata maintenance plan will incorporate the monitoring and treatment of concrete cancer.

Mottling can be caused by building defects, weather, insufficient waterproofing, inadequate concrete cover and quality, earth movement under the build, or saltwater chlorides. The method of treatment will depend on the cause of the problem.

If there is less severe damage, the concrete can be removed, exposed steel replaced and consequently refilled. For buildings with high salt exposure, electrochemical treatment such as cathodic protection will be a more suitable solution.

For buildings where there is low concrete cover, a polymer-modified repair system will be the recommended solution. This involves removing the damaged concrete around the steel and cleaning the reinforcing bars. A steel primer and polymer modified material will then be applied.

Prevention is the best medicine; therefore, once concrete cancer has been repaired, it will need to undergo additional treatment to reduce the risk of water damage and steel corrosion. Waterproofing concrete is essential in preventing concrete damage in the future.

How do you combat efflorescence?

Efflorescence can be removed by use of a pressure washer and wire brush. This needs to be followed by a calcium chloride solution for a final rinse off. The surface then needs to be left for two weeks to ensure the mottling is gone.

As with concrete cancer, prevention is paramount. It is crucial to eliminate sources of moisture to avoid the return of mottling. Some ways of doing this include repairing roofs and installing more effective ventilation systems in high water usage areas, such as bathrooms. Cleaning blocked pipes and gutters and using quality latex chalk to seal cracks in the masonry can also be crucial in prevention. 

Following this, the first coat of paint should be a premium masonry sealer, followed by two coats of premium acrylic paint. Elastomeric wall coating may be slightly more expensive but is extremely beneficial for outdoor areas in increasing tolerance to future outbreaks.

Both concrete cancer and efflorescence can reduce your building’s integrity, appearance and overall value. There is not one single solution for concrete cancer as it depends on the extent of damage and the materials used. It is crucial to get help from licenced professionals to determine an effective plan to enhance the durability of your property.

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