METHOD FOR INJECTING RUST-PROOFING AGENT AQUEOUS SOLUTION INTO CAVITY INSIDE SEALED PC TENDON INSERTION SHEATH IN EXISTING PC STRUCTURE

摘要

PROBLEM TO BE SOLVED: To provide a method for injecting a rust-proofing agent aqueous solution into a cavity inside a PC tendon insertion sheath that can distribute the rust-proofing agent aqueous solution across an entire area inside the grout-unfilled cavity under conditions that clearances among single wires of a PC tendon and clearances among the single wires and a sheath inner surface are narrow and that a hose for injecting the rust-proofing agent aqueous solution cannot be sufficiently inserted up to an upper end of a grout-unfilled portion.SOLUTION: A method for injecting a rust-proofing agent aqueous solution into a cavity inside a sealed PC tendon insertion sheath in an existing PC structure comprises the steps of: inserting a rust-proofing agent aqueous solution injection hose 20 such that a leading end thereof is directed toward an upper end side of a grout-unfilled cavity 12 while causing a depressurization flow passage 16 to communicate with an appropriate position of the grout-unfilled cavity 12 when injecting the rust-proofing agent aqueous solution into the grout-unfilled cavity 12 of an existing PC structure 1; depressurizing the inside of the grout-unfilled cavity 12 via the depressurization flow passage 16; subsequently causing the rust-proofing agent aqueous solution to flow into the grout-unfilled cavity 12 via the rust-proofing agent aqueous solution injection hose 20; and causing the rust-proofing agent aqueous solution to blow out from the leading end of the rust-proofing agent aqueous solution injection hose 20 by flow velocity at the time of the flow into the grout-unfilled cavity 12 and spraying the rust-proofing agent aqueous solution to an upper end of the grout-unfilled cavity 12.