Our client came to us to ask for advice on repairs of concrete cancer after their building inspector had identified exposed, rusting rebar with some cracking on the overhang beam on the side of the cantilevered pool. The concrete scan that the building inspector carried out showed inadequate concrete coverage on one side of the pool beam. With the correct repair process carried out by our Singapore Waterproofing team, the concrete beam is now free of concrete cancer and we are happy to have helped prolong the service life of this concrete structure. (Please read about the concrete repair method further down on this page).
Several factors predetermine the risk of concrete cancer, including proximity to the coastline and a built-up environment; the degree of concrete cover to steel reinforcing; the presence of differential metals; the quality and density of coating systems; inadequate waterproofing; building defects cracking; joint and penetration detailing and the level of preventative maintenance.
One of the most common locations one can find corrosion of reinforcement steel are in columns and beams with the primary cause being lack of concrete cover to protect the steel and/or poor-quality concrete. Other common areas of water-driven concrete cancer are basements, underground car parks, flat concrete rooftops and balconies.
Corrosion of reinforcing steel or other embedded metals is by far the leading cause of premature ageing, deterioration and durability issues in concrete. Concrete cancer can happen in many areas of a concrete structure, so it is a good idea to regularly look out for tell-tale signs so that it can be remedied before it gets severe and becomes a serious problem and starts affecting the strength and structural integrity of the building.
To help prevent spalling from occurring, cracks and holes should be adequately sealed as soon as possible. Cracks can be repaired using a technique called crack injection where suitable epoxy or polyurethane resins are injected. A protective coating, a penetrative concrete sealer or a waterproof membrane will provide a barrier against moisture, salts and chemical attacks.
Unfortunately, the problem is likely to be much more extensive than symptoms on the concrete surface suggest. As steel rusts, it can expand up to eight times its original size, causing the surrounding concrete to break away. Once established, the rusting will spread along the reinforcing in each direction. It is impossible to know the full extent of the damage until the concrete is chiselled away.
Our extensive experience on major civil projects has afforded Singapore Waterproofing opportunities to design with industry-leading engineers and tackle some of the most complex concrete repair challenges imaginable in the built environment. Using this knowledge, we can provide you with a range of options to best meet your project criteria.
The typical method of concrete cancer repair follows a process of:
Once the concrete cancer has been repaired, it is important to take preventative steps to ward off a recurrence. We recommend implementing a maintenance program tailored for the environment the building is subjected to including dedicated inspections. Regular maintenance checks will help identify any problems in the early stages for repairs, which again will help enhance the service life and reduce the life cycle cost of concrete structures.
If you have cracked or damaged concrete and/or moisture/seepage problems in your building, we welcome you to arrange a booking with one of our experienced inspectors to carry out an onsite assessment and provide you with their recommendations and a quotation for remedial repairs. Contact us
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