To provide a high-function water permeable flat plate having high strength, excellent water permeability and excellent aesthetic and scenic properties.
The front layer part of the two layer type flat plate consisting of the front layer part and a base layer part is formed by bonding grains, which are formed by coating aggregate of 2.5 to 10 mm in grain size with cement paste contg. a polymer emulsion, to each other via the cement paste part. In addition, the surface of the front layer part is subjected to finishing. The base layer part is formed by bonding grains, which are formed by coating aggregate of 2.5 to 5 mm with the cement paste, to each other via the cement paste part. The open void volume of the two layer type flat plate is 8 to 15%, the coefft. of water permeation thereof is 0.05 to 0.20 cm/sec and the bending strength thereof is 4.5 to 6.5 N/mm2.
Yatani, Morio
CHICHIBU ONODA CEMENT CORP