cementitious foam insulation
Cementitious foam insulation is a cement-based foam used as sprayed-foam or foamed-in-placed insulation.
One type of cementitious, spray-foam insulation is known as Air-Krete. It contains magnesium silicate and has an R-value of about 3.9 per inch. With an initial consistency similar to shaving cream, Air-Krete is pumped into closed cavities. After curing, it's similar to a thick pudding.
Cementitious foam costs about as much as polyurethane foam. It's also nontoxic and nonflammable. But since cementitious foam is made from minerals (like magnesium oxide) extracted from seawater, it can easily be damaged by water.