Patent ID: 8163352
Filing Date: 2012-04-24
Classification: B28B,C04B,Y02W

Abstract:
1. A continuous method for making structural cementitious panel without defects in its core caused by air voids around embedded chopped fibers by smoothing the top surface of a formed, but not yet set, chopped fiber reinforced cementitious slurry comprising the steps of: applying a first layer of cementitious slurry over a moving carrier, smoothing the first layer of cementitious slurry to evenly distribute the slurry over the entire surface of the slurry and uniformly cover any exposed chopped fibers within the slurry, to eliminate air voids in the slurry around the fibers, and pock marks and grooves in the cementitious slurry, without scratching or tearing the surface of the slurry, the smoothing being performed with a pivotally mounted smoothing device comprising a plate with a stiffening member and a vibrator, wherein the to surface of the first layer of cementitious slurry contacts the downstream portion of the bottom surface of the plate of the smoothing device, while the plate is vibrating, transversely to the direction of travel of the panel, while spacing the upstream portion of the plate from the to surface of the slurry, to smooth the to surface of the first layer of cementitious slurry, applying a first overlayer of fiber directly over the smoothed first layer of cementitious slurry; and embedding the first overlayer of fiber into the smoothed first layer of cementitious slurry to form a first layer of cementitious material having fiber reinforcement comprising uniformly distributed alkali-resistant glass fibers, wherein the cementitious slurry comprises an aqueous mixture of, on a dry basis, 35 to 70 weight % reactive powder, 5 to 20 weight % said alkali-resistant glass fibers, 20 to 50 weight % lightweight filler particles, and wherein the reactive powder comprises, on a dry basis, 35 to 75 wt. % calcium sulfate alpha hemihydrate, 20 to 55 wt. % hydraulic cement, 0.2 to 3.5 wt. % lime, and 5 to 25 wt. % of an active pozzolan, wherein the cementitious material is uniformly reinforced with the alkali-resistant glass fibers and the lightweight filler particles are uniformly distributed in the cementitious material, wherein said lightweight filler particles are selected from at least one member of the group consisting of ceramic microspheres, glass microspheres, fly ash cenospheres and perlite, and wherein the cementitious slurry optionally comprises sand.