Patent ID: 8298332

Claim:
A cement board having a density of about 45 to 85 pounds per cubic foot (0.72 to 1.36 g/cc), and having a continuous phase resulting from the curing of an aqueous mixture comprising: 35-60 parts by weight Portland cement-based binder, 2-10 parts by weight expanded and coated perlite filler having a mean particle diameter of about 20 to 90 microns, 10-50 volume % entrained air, and optional additives selected from one or more members of the group consisting of water reducing agents, set-accelerators, set-retarders; and 0-25 parts by weight secondary filler, wherein the secondary filler is at least one of blast furnace slag, volcanic tuff, expanded clay, shale aggregate, hollow ceramic spheres, hollow plastic spheres, expanded plastic beads and pumice.