Disclosed are formulations adapted to form a foamed cementitious
composition, the foamed cementitious composition itself, a method of
forming a hydraulic binder foam, and a method of conveying and applying
the resulting foam to a substrate. A pumpable cementitious slurry is
formed, the slurry is mixed with a gas such as air, and is subjected to
mechanically created turbulence to generate gas bubbles and create a
foam, which preferably is stabilized by a foam stabilizing agent such as
polyvinyl alcohol present in the slurry. The foam is then conveyed to a
nozzle or other suitable dispense point from which it is applied, for
example sprayed, preferably uniformly, onto a substrate to be coated.
Prior to dispensing, a set accelerator is preferably injected, which
causes the foam to gel, which in turn improves the hangability of the
product on a substrate. The spray material adheres to the substrate and
hardens to form an insulative coating on the substrate. Also disclosed
are dry compositions comprising a hydratable cementitious binder, a
mechanical foam stabilizing agent, and optionally a fibrous component,
set retarder and air entraining agent, said composition providing, on the
addition of water, gas and mechanical turbulence, a settable foam which
is capable of spray application to a steel structural member and which,
after spray application, is adherent to the member in the foamed state
and after setting. The foam after setting, forms a fire and heat
protective adherent coating on the member.