Abstract: Refractory compositions based upon alumina or aluminum silicate chemically bound by aluminum phosphate have a shelf life of three months to more than one year where the composition includes both liquid aluminum phosphate and phosphoric acid to form a portion of the aluminum phosphate binder in situ. In accordance with another embodiment of the present invention, increased strength is achieved by including alumina, and an aluminum silicate bearing material, such as clay, in the refractory composition to form the in situ aluminum phosphate bond from the reaction of phosphoric acid and aluminum silicate. The aluminum phosphate should be provided in the composition in an amount of about 5% to about 70% by weight of the bone dry composition and the phosphoric acid should be included in an amount in the range of about 1% to about 10% based on the weight of the bone dry composition to provide the surprisingly new and unexpected shelf life to the refractory composition.

Abstract: A basic refractory composition includes a magnesium oxide source, aluminum phosphate and an insulating material selected from the group consisting of perlite, vermiculite, diatomaceous earth, and mixtures thereof in an amount of 5.60% based on the total weight of the composition. The composition provides excellent temperature resistance while retaining unexpected strength for a magnesium oxide based chemically bound refractory material having a substantial portion of insulating material.