Construction products detail

The term surface protection system covers a range of different types and designs. Besides polymer-containing coatings for concrete structures, organosilicon compounds can also be used as water repellents in surface protection systems.

Surface protection systems for concrete structures serve to protect concrete and reinforced concrete structures. The goals are:

• to inhibit or prevent the penetration of corrosion-inducing substances that attack concrete (e.g. soft / low-ion water, other liquids, steam, gas, chemicals) or to inhibit or prevent attack by microorganisms,
• to regulate the water content by adjusting and maintaining the concrete moisture within a non-critical range, and
• to increase the resistance of concrete to chemicals and mechanical attack.

Surface protection systems are also used to repair or provide protection against reinforcement corrosion, in particular, to maintain or restore passivity and increase electrical resistance.

In accordance with the 'Additional technical terms of contract and guidelines for engineering structures' (Zusätzliche Technische Vertragsbedingungen und Richtlinien für Ingenieurbauten, ZTV-ING) or the 'Additional technical terms of contract for the repair of concrete structures in hydraulic engineering' (Zusätzliche Technische Vertragsbedingungen für die Instandsetzung der Betonbauteile von Wasserbauwerken, ZTV-W LB 219), a distinction is made between the following surface protection systems:

• OS 1 (OS A): Hydrophobic treatment
  • OS 1 (OS A) is applied to reduce water absorption in vertical and inclined concrete structures that are exposed to weathering, e.g. retaining walls. OS 1 (OS A) is not effective with pressurised water.
• OS 2 (OS B): Coating for surfaces not accessible by foot or vehicle (without scratch coating or levelling filler)
  • OS 2 (OS B) is applied to increase the carbonation resistance of sufficiently drained concrete structures exposed to weathering, conditionally also in the spray zone of de-icing agents.
• OS 4 (OS C): Coating with increased impermeability for surfaces not accessible by foot or vehicle (with scratch coating or levelling filler)
  • OS 4 (OS C) is applied to concrete structures directly exposed to weathering, also in the spray zone (with corresponding verification also in the splash zone) of de-icing agents.
• OS 5a (OS DII) / OS 5b (OS DI): Coating with low crack-bridging capacity for surfaces not accessible by foot or vehicle (with scratch coating or levelling filler)
  • OS 5a (OS DII) / OS 5b (OS DI) is applied to concrete structures exposed to weathering and with cracks close to the surface (with corresponding verification also for structures with separating cracks). The systems may also be used in the spray zones (with corresponding verification also in the splash zone) of de-icing agents.
• OS 11a (OS F a) / OS 11b (OS F b): Coating with increased dynamic crack-bridging capacity for surfaces accessible by foot or vehicle
  • OS 11a (OS F a) / OS 11b (OS F b) is applied to concrete structures exposed to weathering and with cracks close to the surface and/or separating cracks subject to mechanical stress, also in the spray zone or splash zone of de-icing agents, e.g. bridge caps.

Regulatory framework

DIBt prepares evaluations of the fitness for use of surface protection systems in the area of transport infrastructure construction. The evaluations provide independent validation of additional information that cannot be stated in the declaration of performance.

It would also be possible to issue an ETA instead of an evaluation, however, there are no European Assessment Documents (EADs) for surface protection systems as yet.

In accordance with the ZTV-ING and ZTV-W LB 219, the evaluations serve as 'verifiable confirmation' (prüffähige Bescheinigung) and are recognised as equivalent to project-specific verifications when they fully correspond to the construction specifications. The Notes on ZTV-ING (Hinweise zu den ZTV-ING) – Part 3 – Section 4 and the BAWRecommendation 'Repair products – Notes for the expert designer on works-related product characteristics and test methods' (BAWEmpfehlung "Instandsetzungsprodukte – Hinweise für den Sachkundigen Planer zu bauwerksbezogenen Produktmerkmalen und Prüfverfahren") are to be observed to support the construction specifications and the execution of construction work.