Method for injecting injection filler into concrete structure and syringe therefor

A syringe for injecting an injection filler into a crack, rock pocket, and a void portion around a steel bar in a concrete structure, the syringe comprising:

• a container body (10), including an expansion tube having a bellows-like wall surface (10a), to be filled with an injection filler (X);
• an external cylinder (30) at an outer perimeter of the container body (10);
• and
• an injection/outlet (10b) of the container body (10) and a bellows cap (40) having a slit (42a), at one end of the external cylinder (30), the bellows cap (40) communicating with a base (20) having an injection port (21) for pressing the injection filler (X) in, the container body (10) including a rear end communicating with the injection/outlet (10b) by an extrusion part (50), the slit (42a) of the bellows cap (40), and the base (20), the injection filler (X) being pressed into a crack portion (B) by an elastic force of an elastic body (51) of the extrusion part (50), wherein
• the container body (10) is provided at a distal end with the injection/outlet (10b),
• the container body (10) is provided at the other end with a concave pressed portion (10c),
• the pressed portion (10c) has a shape fitted to a convex extrusion portion (54) formed on a pressing plate (53) of an extrusion shaft portion (52) forming the extrusion part (50), and
• the largest diameter of a first pleat (11a) nearest the injection/outlet (10b) at the bellows-like wall surface (10a) of the container body (10) is smaller than the largest diameter of a pleat located at the bellows-like wall surface (10a).