Foam composites and methods of preparation thereof are discussed. For example, the foam composite may include a polymeric material and a particulate filler, wherein the compressive strength of the foam composite is equal to or greater than 20 psi, the density is 4 pcf to 40 pcf, and wherein the thermal conductivity is equal to or less than 0.050 W/m K. the particulate filler may include fly ash, e.g., in an amount of about of 45% to about 75% by weight with respect to the total weight of the foam composite. The foam composite may be prepared from a mixture of a polyol, an isocyanate, the particulate filler, and a liquid blowing agent having a boiling point equal to or greater than 25° C. or 30° C.