Principle 1 - Protection Against Ingress
A large amount of concrete damage is the result of the penetration of damaging materials into the concrete, including both liquid and gaseous materials. Principle 1 - Protection Against Ingress deals with preventing this ingress and includes methods to reduce the concrete permeability and porosity of the concrete surfaces to these different materials.
The selection of the most appropriate method is dependent on different parameters, including the type of material, the quality of the existing concrete and its surface, the objectives of the repair or protection works and the maintenance strategy.
Komerco supplies a full range of impregnations, hydrophobic impregnations and specialized coatings for use in protecting concrete according to the Principles and Methods of EN 1504. A list of methods to protect the concrete surface against liquid and gaseous ingress and product options is outlined below:
1.1 Hydrophobic Impregnations
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, preventing its passage through the pores, but still allowing each way water vapour diffusion.
The standards recognise two classes of hydrophobic protection, dependent upon the level of protection required:
Impregnations differ from hydrophobic impregnations in that the pores and capillaries are partly or totally filled. The standards define impregnations as the treatment of concrete to reduce the surface porosity and to strengthen the surface. This type of treatment usually results in a discontinuous thin film of 10 to 100 microns thickness on the surface. This film serves to block the pore system to aggressive agents.
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.
1.4-1.6 Management of Cracks
All concrete protection works must take account of the position and size of any cracks and joints in the concrete. This means investigating their nature and cause, understanding the extent of any movement in the substrate and its effect on the stability, durability and function of the structure, as well as evaluating the risk of creating new cracks as a result of any remedial joint or crack treatment and repair.
If the crack has implications for the integrity and safety of a structure, refer to Principle 4 - Structural strengthening. This decision must always be taken by the structural engineer and then the selected surface treatments can then be applied successfully.
1.4 Surface Bandaging of Cracks
Surface bandaging of cracks in the concrete involves applying a suitable material over the cracks to prevent the ingress of aggressive media into the concrete.
1.5 Filling of Cracks
Certain cracks that need to be treated to prevent the passage of aggressive agents should be filled and sealed. For non-moving cracks, such as those that have been formed by initial shrinkage or poorly placed concrete, need only to be fully exposed and repaired or filled with a suitable repair material such as:
*High pressure crack injection with one and two-component resin systems is a highly technical and specialist activity. It is recommended that only trained and experienced applicators undertake this type of work and as such, please be in contact here to discuss injection products with a Komerco representative.
1.6 Transferring Cracks Into Joints
Cracks to be treated to accommodate movement should be repaired so that a joint is formed to extend through the full depth of the repair and positioned to accommodate that movement.
The cracks, or joints, must then be filled, sealed or covered with a suitably elastic or flexible material. The decision to transfer a crack to the function of a movement joint must be made by a structural engineer.
1.7 Erecting External Panels
The erection of external panels protects the concrete surface from external weathering and aggressive materials attack or ingress.
1.8 Applying Membranes