Cement mold-making silicone rubber composition

A cement mold formed by casting or coating a silicone rubber composition onto a surface portion of a master pattern and removing the mold from the master pattern,

• said silicone rubber composition comprising
• (A) 100 parts by weight of a polyorganosiloxane having at least two monovalent aliphatic unsaturated hydrocarbon groups each bonded to a silicon atom in a molecule,
• (B) a polyorganohydrogensiloxane having at least three hydrogen atoms each bonded to a silicon atom in a molecule, in such an amount as to provide 0.1 to 5 silicon-bonded hydrogen atoms per monovalent aliphatic unsaturated hydrocarbon group in component (A),
• (C) a platinum base compound in such an amount as to provide 1 to 100 ppm of platinum atoms based on the weight of component (A),
• (D) 5 to 60 parts by weight of finely divided silica having a specific surface area of at least 50 m2/g, and
• (E) 5 to 30 parts by weight of coal ash and/or pozzolan powder.

A cement mold formed by extruding a silicone rubber composition onto a master pattern so as to enclose the master pattern and removing the mold from the master pattern,

• said silicone rubber composition comprising
• (A) 100 parts by weight of a polyorganosiloxane having at least two monovalent aliphatic unsaturated hydrocarbon groups each bonded to a silicon atom in a molecule,
• (B) a polyorganohydrogensiloxane having at least three hydrogen atoms each bonded to a silicon atom in a molecule, in such an amount as to provide 0.1 to 5 silicon-bonded hydrogen atoms per monovalent aliphatic unsaturated hydrocarbon group in component (A),
• (C) a platinum base compound in such an amount as to provide 1 to 100 ppm of platinum atoms based on the weight of component (A),
• (D) 5 to 60 parts by weight of finely divided silica having a specific surface area of at least 50 m2/g, and
• (E) 5 to 30 parts by weight of coal ash and/or pozzolan powder.