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Concrete Repair and Protection
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Concrete Defects and Degradation
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Concrete repair can become necessary due to a number of factors affecting a structure.
Atmospheric conditions, the quality and type of original construction, the degree of maintenance carried out or previously applied repair systems can all play a large part in the degradation of the concrete elements within a structure.
Spalling concrete can be caused by:
- Carbonation
- Chloride and other contamination
- Alkali silica reaction (ASR)
- Corroded reinforcement
- Low reinforcement cover
- Poor construction techniques
- Shrinkage and stress cracking
- Honeycombed concrete
Once any of the above problems have occurred, external conditions can quickly exacerbate the condition especially during the winter period.
The symptoms of these problems can manifest themselves in similar ways. Extensive on-site test surveys backed up by laboratory testing can be carried out where required by Pikehaven to determine the cause and extent of these symptoms.
The client can then be provided with a detailed and effective solution which is long lasting and aesthetically pleasing.
These solutions and recommendations can be presented in report form for specifications to be compiled by the client.
Repair Methods
Selection of the appropriate manufacturer and system to comply with the works specification is carried out in advance by the Pikehaven engineer and agreed by the client. The general procedures are outlined below:
Concrete Repair
1. Carry out a visual and hammer test survey to ascertain and mark out the defective areas of concrete.
2. Test concrete where required for carbonation, chlorides or cement content
3. Break out the defective areas using breakers suited to the size and location of the repairs.
4. Thoroughly clean all reinforcement by mechanical means (needle gun, grit blasting or similar methods).
5. Prime steel and adjacent concrete using the appropriate primers for the system employed.
6. Whilst the primer is still tacky, apply in layers if necessary the concrete repair mortar (resin or cementitious) by hand and finish using a steel trowel to the original profile.
Protective Coatings
These come in three main types:
Cementitious Fairing Coat
This is a levelling coat applied by trowel to a dampened concrete substrate at a thickness of 2-3mm to level the surface and provide extra cover protection.
Smooth Anti-carbonation Coating
This is a decorative coating similar in appearance to masonry paint that gives carbonation protection.
Elastomeric Anti-carbonation Coating
This is a decorative coating that provides carbonation protection and remains flexible to bridge cracks that might move.
Cracking in Concrete
Cracks can be caused by stresses in the structure from loading or foundation movements or shrinkage, expansion and other site or design problems.
They can be repaired by chasing out and repairing using the above specifications or by resin injection (see the section on Resin Injection).
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