What do we need to look out for in a Concrete Slab upgrade?
When considering the FRL upgrade of Concrete elements thorough investigation is required and some of the salient points are:
- Checking compliance of the overall Concrete thickness of the Slab member.
- Checking compliance of Concrete cover to the Top Steel reinforcing members.
- Checking compliance of Concrete cover to the Bottom Steel reinforcing members.
- Checking compliance of Concrete cover to the Beam/Column Tendon members.
Surely the spray will adhere to a concrete slab without any particular precautions?
The bonding surface offered by the concrete should not be overlooked. The surface should be unpainted without contamination from compounds such as formwork releasing agents, oils, grease, etc which may impede the proper adhesion of the Vermitex 'AF'.
We have specified the correct thickness of Vermitex to upgrade the slab, have we overlooked anything?
Even though a Concrete element may be fire upgraded with sprayable materials special attention should still be directed at ensuring that the appropriate Fire Resistance system is installed in Constructions joints, Control joints and Expansion joints. It must also be noted that lightweight Fire Protection materials have little or no compressive strength and cannot be relied upon as a replacement for concrete cover for the net structural requirements of the member(s) in question.
What precautions are needed in rectification of Fire affected buildings?
In fire affected buildings and in particular with fire damaged concrete it is advisable that specialist engineering advice be sought. Significant changes in concrete design strength (normally occurring at 300° C) result in color changes of the concrete aggregates, which are most frequently used. Texture and hardness changes are the superficial signs of temperature effects of concrete that has been significantly heated. Fire spraying over these areas is possible, in order to reinstate the original Fire Resistance Levels, however the net structural requirements of the member need to be addressed.