REINFORCED CONCRETE REPAIRS

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THE PROBLEM

Corrosion of the reinforcing bars embedded in concrete causes expansion of the bars, which results in cracking and eventually spalling of the concrete covering. Apart from the strength and aesthetic losses the detachment and falling of concrete cover may result in human casualties.

INDICATIONS

• Cracks appear on the concrete surface in the direction of the embedded reinforcing bars. Note that corrosion of smaller diameter bars, such as the stirrups, does not usually cause any cracking. For example, vertical cracks appear 3-6cm from the edges of columns due to main re-bar corrosion, but no horizontal cracks.

• Spalling (detachment) of the concrete cover and exposure of corroded reinforcing steel

• Parallel cracks appear at the bottom of reinforced concrete slabs. It mainly occurs in areas exposed to high moisture, such as the bathroom or kitchen ceiling, the roof slab or in an area of prolonged water infiltration.

REPAIR PROCESS

1. Removal of the concrete cover to expose the corroded reinforcing bars

2. Replacement of any deteriorated bars with new ones

3. Cleaning of the surface of the corroded re-bars and application of a protective coating

4. Reinstatement of the removed concrete cover with GUNITE or prepackaged polymer modified mortar class R4

5. Reinstatement of plaster with cement mortar containing SBR or acrylic admixtures and polypropylene fibers.

6. Application the final rendering layer and painting