A solidified, thermally insulating composition

A thermally insulating composition comprises: (A) an aqueous liquid, wherein the aqueous liquid is the continuous phase of the composition; (B) a particulate, wherein the particulate is silica, and wherein the particulate is a dispersed phase of the composition; and (C) an activator, wherein the activator causes at least some of the particulate to aggregate and form a network of at least the particulate, wherein the formation of the network causes the insulating composition to become a gel, and wherein the gelled insulating composition inhibits or prevents heat loss from two areas having different temperatures. A method of thermally insulating a portion of an annulus comprises: introducing the insulating composition into a portion of an annulus, wherein the gelled insulating composition inhibits or prevents heat loss from the portion of the annulus to an area adjacent to the outside of a second object.