What is concrete cancer?
This occurs when reinforcements(steel bars) in the concrete start to corrode then expand, displacing concrete around it and causing it to become brittle and forms cracks thus accelerating the process.
Signs of concrete cancer
- Crazing and cracking concrete.
- Rust stain emerging from the concrete seem to leak out.
- Concrete expanding outward
- Bubbling of concrete render.
- Leak which may appear in overhead concrete surface.
Causes of concrete cancer
There are many reasons for the cause of concrete cancer. The common reasons includes1. Stress failure from excessive weight
When concrete member like slab carries an excess load which it was not designed for it, one of the side effect is stress fracture. When the fracture occurs there is an open path for water and moisture to get into the concrete and get into contact with steel reinforcement, causing the reinforcement to corrode.
2. Insufficient concrete cover and poorly poured concrete.
If cover is insufficient , cracks may appear due to external forces/stress like peaple weight or rain. Also, poorly poured concrete causes the concrete element to be porous and sometimes exposes reinforcements directly to the air and moisture/water. This leads to corrosion/rusting of the reinforcements.
3. Poor water proofing.
Water proofing refers to the process of making a concrete element water resistant. It helps to avoid rain water, moisture and leaking into structural element causing concrete cancer.
4. Reinforcing bars being to close to the surface
5. Movement of the earth under the building leading to cracks.
Some of the recommended solution for concrete cancer.
1. Polymer modified repair system solution.This option removes concrete around the reinforcements and clean them, before applying both steel primer and polymer modified materials.
2.Electrochemical treatment like cathodic protection.
This is useful in case of chloride contamination in building near the ocean.
3. Simple replacement method.
Involves removing the demaged concrete , clean and replace the rusted, exposed steel and fill in the cracks.
