Oiles Industry Co., Ltd.

Japanese National Railways

Toshiyuki Kitta

Wataru Abe

Hiroshi Tada

Tadaaki Takase

Keizo Ishikawa

A tendon for prestressed concrete wherein inorganic particles are coated on an outer surface of a rod made of fiber reinforced plastic through a plastic adhesive layer. The inorganic particles are formed with minute rugged surface portions on the outer surface of the tendon for prestressed concrete, the rugged surface portions being firmly adhered to concrete. The inorganic particles are coated on the whole outer surface of the tendon for prestressed concrete, on the fixed portions at both ends, or on the fixed portions at both ends and on a portion subjected to the maximum bending moment.

Tendon for prestressed concrete

In a prestressed concrete structure executed by posttensioning method, a metallic sheath having an inner peripheral surface thereof in sliding contact with a tendon coated with a solid lubricating coating including polytetrafluoroethylene (PTFE). By the use of this metallic sheath, the sliding frictional resistance produced between the metallic sheath and tendon when the tendon is subjected to tensioning operation is considerably decreased to increase the prestressing force introduced into the structure accordingly. The solid lubricating coating is excellent in flexibility and contact properties, and good characteristics of coating are imparted to the sheath.

Metallic sheath for posttensioning method

A metallic sheath for a posttensioning method wherein an outer peripheral surface or outer and inner peripheral surfaces thereof is (or are) coated with phosphate layer (or layers) and plastic resin layer (or layers) thereupon and preferably further coated with a solid lubricating layer upon the inner peripheral surface of the sheath. The phosphate layer of the outer peripheral surface protect the metallic sheath from corrosion by negative ion within concrete, while, on the other hand, that of the inner peripheral surface prevents the electrochemical corrosion between the inner peripheral surface of the sheath and tendon. Moreover, if a solid lubricating, layer is provided at the inner peripheral surface of the sheath, the sliding friction between the metallic sheath and tendon can be decreased so that prestressed force can be increased as much.

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Omiya, Japan

Toshiyuki Kitta