Steel profiles used in composite floor decks are generally hot dip galvanising as standard. When installed over an aggressive environment, however, additional painted coatings are applied to provide further protection and help ensure the composite floor meets its intended design life.
Protective coatings and finishes naturally degrade over time, even in perfectly dry, non-aggressive environments. Galvanising loses at least 0.1 microns of thickness per year, meaning that, in perfect conditions, a 20-micron coating could last for 200 years! Of course, conditions are rarely, if ever, perfect, and so solutions have to be created accordingly.
What is classed as an ‘aggressive environment’?
In a composite floor deck, the steel profile is the lowest layer of the floor build-up, and is typically left visible to the space below. It can therefore act as the ceiling to a heated or unheated internal space, or as a soffit to an exposed or semi-exposed external space.
Aggressive internal environments include swimming pools, where the combination of heat and humidity – as well as chlorine content in the air – speeds up that natural degradation of protective finishes. Even leisure spaces like gyms and changing rooms can, ultimately, be classed as more aggressive than the ‘perfect’ dry environment we talked about above.
Car parks are perhaps the most common example of a semi-exposed space. Wind and rain blow in through the openings and, along with vehicle exhaust fumes, attack the floor deck soffit, increasing the rate at which protective finishes degrade.
These scenarios are among the most aggressive that a floor deck profile is likely to be exposed to. Many other types of internal and external spaces – of varying temperature, humidity and exposure – exist between perfectly dry and aggressive environments. There are also factors such as site location, and whether the environment is inland or coastal, to take into account.
BS EN ISO 14713-1:2017 Zinc coatings - guidelines and recommendations for the protection against corrosion of iron and steel in structures. General principles of design and corrosion resistance defines different environments, and can be used to offer appropriate solutions.
What is Tata Steel’s Colorcoat FD® 170 pre-finished steel for aggressive environments?
To provide additional protection to traditional galvanised steel deck profiles, Tata Steel offers Colorcoat FD® 170 pre-finished steel. It has a design life of 60 years, and project-specific guarantees of up to 25 years are available for paint adhesion and colour fade.
The durable, 170-micron thick, satin embossed plastisol coating is applied to the steel before being formed into the deck profile. This achieves a more comprehensive and consistent finish compared to painting steel that has already been formed into profiles, where it is difficult to ensure complete coverage in areas like dovetail sections.
Colorcoat FD® 170 is ideal for exposed soffits in both internal and external environments. It can be specified with the ComFlor® 60 and ComFlor® 80 profiles, which are part of the range of seven unique ComFlor® composite deck profiles offered by Tata Steel. The ComFlor® deck range delivers solutions for specific applications, and includes low profile and deep deck options.