Patent ID: 8846776

Claim:
A rigid composite material comprising: a polyurethane formed by the reaction of an isocyanate selected from the group consisting of diisocyanates, polyisocyanates and mixtures thereof, and at least two polyols, the at least two polyols comprising: a high hydroxyl number polyol selected from the group consisting of polyether polyols and polyester polyols, the high hydroxyl number polyol having a hydroxyl number greater than 250 and having 75% or greater primary hydroxyl groups, wherein the high hydroxyl number polyol includes an aromatic polyester polyol and wherein the high hydroxyl number polyol comprises from about 1% to about 25% by weight of the total polyol content used to form the polyurethane, and a low hydroxyl number polyol selected from the group consisting of polyether polyols and polyester polyols, the low hydroxyl number polyol having a hydroxyl number of 250 or lower; and from about 40% to about 90% by weight coal ash, wherein the composite material has a density of 5 lb/ft 3 or greater.