US Patent 7833344 Ultra low density cement compositions and methods of making same

A slurry composition comprising an alkaline metal oxide, a chloride or phosphate salt, water, glass beads and a foaming agent. A foamed slurry comprising magnesium oxide, water, a chloride or phosphate salt, and glass beads, wherein the slurry has a density of from about 4 to about 12 pounds per gallon. A foamed slurry comprising magnesium oxide, water, a chloride or phosphate salt, and beads, wherein the slurry has a density of from about 4 to about 12 pounds per gallon and the set slurry is acid soluble.