Vermiculite fire spray
Vermiculite fire spray is an inexpensive form of fire protection that provides up to 240 minutes of protection to structural steel, ceilings and ducts.
Vermiculite is quite often a cheaper option than intumescent coatings at FRLs of 90 or 120 minutes.
Vermiculite retains moisture that is released as steam in the event of a fire. The ensuing cooling effect delays the temperature increase of the steel providing a level of protection.
Whilst vermiculite is inexpensive, both in terms of material cost and application, it doesn't provide the aesthetically pleasing qualities of intumescent coatings.