Patent ID: 8642160

Claim:
A reinforced cementitious board system, consisting of: a core layer of cementitious material having opposed planar surfaces and opposed edges; at least one outer layer of an alkali resistant fiberglass mesh reinforcement embedded in the opposed planar surfaces of the core layer, and wherein the fiberglass mesh reinforcement is a mesh scrim having about 4×4 to 6×6 strand per inch construction in the longitudinal and transverse direction, respectively, and wherein the fiberglass mesh reinforcement is made from a coated fiberglass yarn, the yarn in an uncoated state has a nominal density of about 1200 to 5000 linear yards per pound of fiberglass yarn, and the coated yarn comprises 40-65 wt. % coating comprising alkali resistant polymer and 35-60 wt % fiberglass yarn on a dry basis; wherein the cementitious material comprises: 25 to 60 wt. %, on a wet basis, cementitious reactive powder comprising Portland cement, 10 to 40 wt. % water, 1 to 70 wt. %, on a wet basis, of filler; optional additive selected from at least one member of the group consisting of water reducing agents, chemical set-accelerators, chemical set-retarders, air-entraining agents, foaming agents, shrinkage control agents, coloring agents, viscosity modifying agents and thickeners, and internal curing agents; and wherein the system allows for bonding of the mesh scrim to the core layer with a bond strength of 30 to 52 lbs for a board made with coated 4×4 strands per inch fiberglass scrim compared to a bond strength of about 20 to 25 lbs with an identical core layer composition using an 8×8 strand per inch coated fiberglass scrim, wherein the cement board system only needs to be scored once on each planar surface to allow for easy snapping of the cement board along the score line during installation of the cement board, compared to two scores on each planar surface to allow for easy snapping of the cement board along the score line during installation of the cement board having a 8×8 strand per inch fiberglass scrim, and wherein the mesh scrim is covered on its entire surface with the cementitious slurry and is embedded between about 0.03 to about 0.06 inches into at least one of the planar surface of the cement core layer, and optionally at least one outer layer of said fiberglass mesh reinforcement on one pair of the opposed edges of the core.