Composite panels and methods of preparation are described herein. In some embodiments, the composite panel can include a first fiber reinforcement, a polyurethane composite having a first surface and a second surface opposite the first surface, wherein the first surface is in contact with the first fiber reinforcement; and a cementitious material adjacent the first fiber reinforce-opposite the polyurethane composite. The polyurethane composite can be formed from (i) one or more isocyanates selected from the group consisting of diisocyanates, polyisocyanates, and mixtures thereof, (ii) one or more polyols, and (iii) a particulate filler. The fiber reinforcement can be formed from a woven or non-woven material, such as glass fibers. The composite panel can further include a material, such as a second fiber reinforcement and a cementitious layer, in contact with the second surface of the polyurethane composite. Articles comprising the composite panels are also disclosed.

A moisture-proof structure comprises a first fire brick layer, a second fire brick layer, a third fire brick layer, a fourth fire brick layer, a fifth fire brick layer and a floor/ceramic tile layer arranged from bottom to top. The five fire brick layers are all laid by using stretcher bond, the fourth fire brick layer is laid by using a means of header bond, upper and lower layers of the first fire brick layer, the second fire brick layer, the third fire brick layer, the fourth fire brick layer and the fifth fire brick layer are bonded by using a cement slurry, a gap between fire bricks of the first fire brick layer is filled with lime powder and fire bricks of the fourth fire brick layer and the fifth fire brick layer are closely connected.