A method of serving a wellbore comprising placing a slurry composition comprising an alkaline metal oxide, a chloride or phosphate salt, water, glass beads and a foaming agent into a wellbore and allowing the composition to set. A method of servicing a wellbore comprising foaming a 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, placing the slurry in a wellbore, and allowing the composition to set. A method of temporarily plugging a wellbore comprising placing in the wellbore a cement slurry comprising magnesium oxide, water, a chloride or phosphate salt, a foaming agent and beads, wherein the slurry has a density of from about 4 to about 12 pounds per gallon, allowing the composition to set, and removing the composition by contacting the set composition with acid.