Method of producing concrete composite pipe

Claim 1

A method of producing a concrete composite pipe comprising the steps of (a) rotating a drum mold about an axis thereof; (b) casting concrete into said drum mold to shape said cast concrete into a concrete layer of a uniform thickness on an inner surface of said drum mold by means of a centrifugal force generated by said rotation of said drum mold; (c) increasing said rotation of said drum mold to obtain an increased centrifugal force such that water is squeezed out of said concrete layer onto an inner surface thereof; (d) stopping said rotation of said drum mold to remove said squeezed water from said concrete layer; (e) resuming said rotation of said drum mold while casting a mixture of hydrophilic resin and a hardener thereinto to form a corrosion protective layer of said mixture on said inner surface of said concrete layer by means of a centrifugal force generated by said resumption of said rotation of said drum mold before said concrete layer solidifies; (f) continuing said rotation of said drum mold while scattering aggregates including coarse and fine particles onto an inner surface of said corrosion protective layer before said concrete layer solidifies; (g) increasing said rotation of said drum mold to increase said centrifugal force such that said coarse particles are caused to precipitate in said corrosion protective layer before said concrete layer solidifies and penetrate into said concrete layer to form a layer intermediate said concrete layer and said corrosion protective layer in the form of a layer of mixed resin, concrete and coarse particles, and such that said fine particles are distributed near said inner surface of said corrosion protective layer; and (h) stopping said rotation of said drum mold after said corrosion protective layer is hardened.

Claim 2

A method of producing a concrete composite pipe comprising the steps of (a) rotating a drum mold about an axis thereof; (b) casting concrete into said drum mold to shape said cast concrete into a concrete layer of a uniform thickness on an inner surface of said drum mold by means of a centrifugal force generated by said rotation of said drum mold; (c) increasing said rotation of said drum mold to obtain an increased centrifugal force such that water is squeezed out of said concrete layer onto an inner surface thereof; (d) stopping said rotation of said drum mold to remove said squeezed water from said concrete layer; (e) resuming said rotation of said drum mold while casting a mixture of hydrophilic resin and a hardener thereinto to form a corrosion protective layer of said mixture on said inner surface of said concrete layer by means of a centrifugal force generated by said resumption of said rotation of said drum mold before said concrete layer solidifies; (f) continuing said rotation of said drum mold while scattering aggregates including coarse and fine particles onto an inner surface of said corrosion protective layer before said concrete layer solidifies; (g) increasing said rotation of said drum mold to increase said centrifugal force such that said coarse particles are caused to precipitate in said corrosion protective layer before said concrete layer solidifies and penetrate into said concrete layer to form a layer intermediate said concrete layer and said corrosion protective layer in the form of a layer of mixed resin, concrete and coarse particles, and such that said fine particles are distributed near said inner surface of said corrosion protective layer; and (h) stopping said rotation of said drum mold after said corrosion protective layer is hardened.