Today’s commercial buildings are built with steel and concrete but the reinforcement of concrete with steel rods called rebars can generate a problem. Because concrete is a porous material, air, moisture, or water can slip in through the tiny cracks and corrode the steel rods within the structure.
The steel reinforcements begin to rust and expand, displacing the surrounding concrete and causing it to become brittle and crack. This is known as concrete cancer or, as it’s more technically known, spalling. And this exposure to foreign elements can cause a vicious cycle.
Once it starts, the level of corrosion can quickly accelerate, tragically compromising the structural integrity of the commercial property.
The moment a building structure displays signs of concrete cancer, repair and restoration must get underway. Using crane hire services and the right treatment option, builders can quickly perform concrete restoration before the issue becomes a costly problem.
Signs of concrete cancer
The extent of damage caused by concrete cancer can be determined by building management and structural engineers, who can quickly spot the signs. Recognizing the signs of concrete cancer will ensure immediate action can be taken to avoid further damage.
The common tell-tale signs that a building has concrete cancer are:
- The appearance of rust stains that seem to originate from within the concrete
- Cracking, crumbling, or flaking concrete
- Concrete render bubbling or plating
- Damp patches and leaks on the concrete roof or internal walls
Neglecting to address these signs can mean the concrete slabs become unsalvageable and a more expensive repair is required. These warning signs can also indicate that major building damage has occurred, meaning the structure has lost its value.
To properly address concrete, it pays to know how to diagnose and correct the problem. This means understanding the common causes of concrete cancer as well as what tools and equipment are needed.
Common causes of concrete cancer
There are several reasons why concrete cancer can occur. Below, we list five things that can compromise concrete’s structural soundness:
Failure to properly waterproof concrete is typically a result of poor workmanship and using the wrong waterproofing membrane. A lack of ongoing maintenance and remedial waterproofing can also contribute to water damage.
Moisture damage can affect more than just a building’s structural integrity. It can also result in the growth of mold and algae, lowered indoor temperatures (which can increase energy bills), and respiratory diseases such as asthma and bronchial infections.
Incorrect placement of steel
If steel rods are placed out of position in the concrete slab, the concrete is unable to properly carry a load. This can lead to the formation of cracks, and if these cracks are not addressed in time, spalling of the concrete can occur.
Building defects are the result of cost-cutting measures (which can vary from poor design or poor workmanship to the use of low-quality materials). Post-construction, these defects can have a severely negative impact on the performance and maintenance of a building.
Occurrences of defects are a serious safety issue, particularly during the occupancy stage. A deformity can influence serviceability and result in segments of the building experiencing concrete cancer.
Buildings situated in coastal areas around the globe are subject to extreme weather and other nature-related hazards, chief of which is saltwater intrusion.
The invasion of salt and moisture can quickly cause concrete to deteriorate, exposing its interior steel beams to salt and moisture and accelerating corrosion.
Poor quality materials
Concrete is made up of three basic components; cement, water, and aggregates such as sand, rock, or gravel. If any of these components (particularly aggregate) is made of poor quality materials, durability will be compromised.
This leads to reduced strength and an increase in concrete shrinkage or stress fractures.
Insufficient concrete cover
The depth and quality of your building’s concrete cover will be a strong indicator of how susceptible the reinforcing steel bars would be to corrosion. A lack of sufficient concrete cover will result in greater carbonation and chloride ingress.
Varying temperatures can also significantly impact concrete structural elements. Without enough concrete cover when extreme temperatures are prevalent, steel reinforcements can suffer progressive deterioration and serious damage.
These issues can all lead to concrete cancer and result in premature concrete deterioration.
Fixing the issue
If you suspect a building site has concrete cancer, it must be treated immediately.
To treat the cause of the problem, a qualified engineer will perform a diagnostic analysis of the spalling. A structural engineer will outline the materials and equipment necessary to correct the problem.
- One of the main solutions for concrete cancer is a simple replacement method. This is an excellent method of repair as construction site cranes can quickly remove the damaged concrete, allowing the rusted, exposed steel to be cleaned and treated with anti-corrosives before the cracks are filled in and a fresh render is applied.
The use of cranes, like a self-erecting crane, will allow the contractor to localize the repair area rather than replace the whole wall, saving time and money.
- Electrochemical treatment is another repair method that can be used to treat concrete cancer. This is particularly useful in buildings in coastal areas that have suffered from a case of chloride contamination. This treatment will use a special concrete repair solution like cathodic protection to protect the structure and metalwork from corrosion.
- If low concrete cover or concrete carbonation are the cause of spalling, a polymer-modified repair system might be used. In this situation, the damaged concrete is removed with the help of crane services so that the reinforcing steel bars can be cleaned.
Once the steel bars are cleaned, they are treated with a steel primer and a polymer-modified material is applied. New concrete is then placed and the repair area is treated with an anti-carbonation protective coating.
Concrete cancer isn’t just unsightly — it can indicate a more severe issue with a building’s structural integrity. Keep an eye on your commercial structures and deal with any minor cracks you see straight away.
When it comes to concrete damage, prevention is the best cure. Building managers must enforce a strong remedial maintenance program to ensure minor cracks and repairs don’t become more costly issues in the future.
Hermann Buchberger is the Founder and CEO of Active Crane Hire (ACH). He’s taken the company from start-up to Industry Leader offering the largest fleet of construction cranes in Australia. ACH launched a new type of crane previously unheard of in the Australian market: electric tower cranes. The company’s infrastructure and associated services now comprise a fleet of trucks and trailers, a crane-rigging team, mobile crane technicians, a fleet of service vehicles, and an extensive range of crane spare parts.