|Concrete cancer/spalling is caused when the concrete substrate cracks and water penetrates the steel reinforcement deep inside the concrete. Once this occurs the steel reinforcement begins to rust, which inturn can cause the steel to expand up to 7 times its original size and thus also causing the surrounding concrete to be displaced. As the steel pushes the concrete away, more water gets to the steel expediting the process.
Concrete cancer/spalling is not only a visual eye-sore, but it also is major contributor in causing the weakling the structural integrity of a building facade and concrete substrate.
|When treating concrete cancer/spalling it is important to make sure that a experienced contractor and specialised products are used to avoid the cancer from continuing to spread below the concrete surface.
Concrete repair can be a cost effective option to full replacement, and is much less time consuming to perform. The new patch material can be seamlessly blended into your concrete structure to make the reapirs virtualy unnoticeable.
The concrete repair process should include the following:
- Carefully examine the concrete surface for evidence of visible concrete cancer and spalling.
- Break out all loose concrete surface to sound substrate
- Prepare bars by grit blasting and / or mechanically clean and / or hand clean
- Chase into concrete along the rusted steel bars until a minimum of 25mm of original profiled steel is exposed
- Re-examine the integrity of existing rushed steel bars to determine which need to be cut and replaced, if required
- Cut and replace existing rushed steel bars with equivalent by welding new steel bars to existing, if appropriate and required
- Install additional bars/rods and fasten into existing footing and existing band beam using chemsets , if required.
Prepare and apply slurry coat to cleaned steel with a surface primer.
Restore concrete cavities to original line and profile using a concrete repair mortar.