Concrete cancer Incidence

Concrete cancer is increasingly common in structures which have not been sufficiently waterproofed.

As builders cut costs on waterproofing membranes, the problems are increasing. The incidence of concrete is particularly high in countries such as Australia where liquid applied membranes are still commonly used.

Liquid membranes are often used inappropriately, and lead to water penetrating into the concrete.

If early symptoms including the presence of calcium stalactites beneath the slab and visible rust from the slab are apparent, a stop leak specialist should be called immediately to assess the potential for damage.

An example of concrete cancer

Concrete Repair FAQs

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Concrete Cancer is a form of concrete failure and can occur in several forms:

• Water penetration causes the concrete reinforcement to rust and vibrate.
  The presence of Chloride compounds, {together|jointly} with a reduction in alkalinity can cause corrosion of the reinforcing steel bars, which in turn creates stresses on the concrete which can then spall (break away).
• Alternatively, if the cement is too alkaline, it reacts with carbon dioxide in the atmosphere and the structure will begin to deteriorate as star-shaped cracks appear. This in turn allows the entry of rainwater which escalte the deteriotationparticualty if climate the local creates freeze-thawing of water in the cracks, ccelertaing the the spaling.

The initial cause of concrete cancer is usually water penetration.
When calcium oxide reacts with water that penetrates the concrete it forms a solution of calcium hydroxide whihc over time will reach the edge of the concrete slab. When this happens the solution reacts with carbon dioxide in the air and transforms into calcium carbonate. On the top of the slab, calcium carbonate causes cracks above the slab (allowing more water penetration, and below the slab stalactites form.

Treatment

Concrete cancer can be treated in some structures.
In order to effect repairs, the spalled concrete must be removed and any exposed steel must either be replaced or cleaned and treated. The area is then repaired to the original concrete profile using cement mortar, epoxy mortar or concrete, depending on the size of the damage and the structural requirements. Cracks are repaired using suitable epoxy resins, special mortars and injection techniques.

This process is referred to as 'crack injection' and may constitute a negative membrane. Negative membranes will not prevent water from entering the concrete, merely shift the water's direction through the slab. Treatment of concrete cancer must incorporate proper waterproofing or risk being a temporary solution.

Portions of this information was sourced from: