What is it?
Concrete cancer is concrete degradation caused by the presence of contaminants or the action of weather combined with atmospheric properties. When concrete cracks, water penetrates through causing the steel reinforcement deep inside to rust. Rusting steel then sheds its skin forcing the layers of rust to push away the concrete surrounding it. This results in large or small pieces of concrete falling away and allowing steel reinforcement to become even more corroded and may cause devastating wear on both the steel and the concrete.
How to detect it?
On the outside of the affected concrete you will see rust stains, broken concrete or even rusted steel reinforcement poking through your concrete slab, walkway, garage, flat roofs, balcony edges etc. However, what you can’t see is the spread of the “cancer” throughout the concrete, and this will continue to spread if left untreated.
How to treat it?
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 utilising appropriate remedial building solutions.
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.