Mark Shaw, Technical Manager – Refurbishment, Sika UK, discusses Sika’s protective concrete coating solutions and total corrosion management systems.
Best practice guidance on the specification of appropriate repair and remedial strategies puts emphasis on ensuring that the quality of a coat is up to scratch.
As well as addressing the underlying issues it’s about repairing a structure so that it is long-lasting a fit for the future.
The first step of every concrete repair process starts with identifying the underlying causes of the problem. Concrete deterioration can usually be attributed to one of four main causes: mechanical, chemical, physical or fire.
For reinforcement corrosions the three common causes of defects are carbonation, corrosive contaminants and stray currents.
These underlying issues can be accelerated under certain environments, such as in aggressive ground conditions or where the concrete is subject to chloride exposure. However, if the right treatment is supplied, such as those developed by Sika, corrosion can be stopped completely.
Sika has developed a wide range of anti-corrosion solutions suitable for concrete, steel, tank lining and anaerobic digestion tank applications. The coatings take into account design life, operational requirements, surface design and installation details to deliver a high level of protection against corrosion.
Protective coatings can prevent further water ingress by creating a barrier between the substrate and the exposed environment.
Specifying a vapour permeable barrier, such as Sikagard 550W, will reduce the risk of corrosion and avoid blistering from trapped moisture. The protective coating also provides crack bridging and carbonation barrier.
In certain circumstances concrete can be porous and damp. In these situations applying a vapour permeable barrier can prove problematic, therefore a polymer modified cementitious system such as Sika MonoTop is recommended.
Sika MonoTop has been developed for instances where concrete is damp whilst also providing a levelling system for damaged or uneven substrates. Alternatively, cementitious or ‘fairing’ coats can be used alongside anti-carbonation coatings to prevent delimitation and add further protection.
A surface coating can be a simple and cost-effective method for extending the life of concrete and improving its appearance. However, surface coatings can only make up one part of an overall concrete protection system and in most cases will not provide the total solution.
For a complete solution, total corrosion management is the answer. Although the majority of reinforced concrete is trouble-free and low-maintenance, when problems arise these often occur at depth and most notably to the reinforcement.
Sika offers a wide range of systems that cover concrete repair and protection in accordance with the Principles and Methods defined in the European Standard EN 1504. Sika is the only single source supplier of a total corrosion management solution offering design support and product guarantees which enable clients to ensure compatibility with the correct specification of concrete repair.
Architects, specifiers and end users must deal with concrete corrosion using a ‘total’ approach that not only controls corrosion but offers a long term outcome to extend the life of a structure. Total corrosion management incorporates mortars, coatings and reinforcement corrosion protectors and will rehabilitate and restore concrete surfaces to ensure they are fit for the future.
Welwyn Garden City
Telephone: +44 (0) 1707 394444