Principle 2 - Moisture Control

The second principle concerns adjusting and maintaining the moisture content in the concrete.

In some situations, such as where there is a risk of further alkali aggregate reaction, the concrete structure has to be protected against water penetration. This can be achieved by the use of different types of products including hydrophobic impregnations, surface coatings and electrochemical treatments.

Komerco partners with the leading businesses and pioneers in concrete technology and can offer a suite of deeply penetrating silane and siloxane hydrophobic impregnations, plus durable acrylic and other resin based protective coatings. Several of these are also tested and approved for use in conjunction with the latest electrochemical treatment techniques.

There is significant overlap between the methods and treatments outlined in Principle 1 in Principle 2, a list of which is outlined below: 

2.1 Hydrophobic Impregnation

A hydrophobic impregnation is defined as the treatment of concrete to produce a water-repellent surface. The pores and capillary network are not filled, but only lined with the hydrophobic material. This functions by reducing the surface tension of liquid water, thus preventing its passage through the pores, but still allowing each way water vapour diffusion.

These products are based on silane/siloxane hydrophobic impregnation technology, that penetrate deeply and provide a liquid water repellent surface. The standards recognise two classes of hydrophobic protection, dependent upon the level of protection required: 

1.1.1 Class I - Penetration <10mm
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1.1.2 Class II - Penetration >10mm

 

2.2 Impregnation Coatings

An impregnation is defined as the treatment of concrete to reduce the surface porosity and to strengthen the surface. The pores and capillaries are then partly or totally filled. This type of treatment usually also results in a discontinuous thin film of 10 to 100 microns thickness on the surface. This serves to block the pore system to aggressive agents.

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2.3 Surface Coatings

Surface coatings are defined as materials designed to provide an improved concrete surface, for increased resistance or performance against specific external influences.

Fine surface cracks with a total movement of up to 0.3 mm can be safely repaired, then sealed and their movement accommodated by the use of elastic, crack bridging coatings, which are waterproof and carbonation resistant. This will accommodate thermal and dynamic movement in structures subject to wide temperature fluctuation, vibration, or that have been constructed with inadequate or insufficient jointing details.

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2.4 Erecting External Panels 
The erection of external panels protects the concrete surface from external weathering and aggressive materials attack or ingress. As long as the concrete surface is not exposed, no water can penetrate and the reinforcement can not corrode.