Sumitomo (sei) Steel Wire Corp.

Sumitomo Electric Industries, Limited

Takashi Ichiki

Jun Sugawara

Masato Yamada

Shingo Nakajima

Katsuhito Oshima

Yoshihiko Touda

Shuhei Maeda

Kiminori Matsushita

Toshihiko Niki

Tomoya Maekawa

Takahide Saiki

Provided is a pregrouted PC steel material comprising a PC steel stranded wire composed of a plurality of steel wires, a pregrout layer disposed on the outer periphery of the PC steel stranded wire so as to accommodate the PC steel stranded wire, a sheath covering the outer periphery of the pregrout layer, and a capsule including a pregrout-hardening agent and a film with which the agent is covered, the capsule being interposed among the steel wires constituting the PC steel stranded wire. The capsule has a strength such that the capsule is not broken before tensioning the PC steel stranded wire but is broken by a tensile force during the tensioning. Also provided is a method for hardening the pregrout layer.

Pregrouted PC steel material and method for hardening pregrout layer thereof

In one aspect, the present disclosure relates to a high-strength prestressing strand having a seven-wire structure in which one core wire and six outer wires are stranded. An external diameter of the strand is from 15.0 mm to 16.1 mm, a total cross-sectional area of the strand is 135 mmor more, and a load at 0.2% permanent elongation is 266 kN or more. A relaxation value measured after a 1000-hour relaxation test is 2.5% or lower and a diameter of the core wire is 5.35&#xb1;0.3 mm and a diameter of the outer wires is 5.15&#xb1;0.25 mm. The core wire and the outer wires each have a composition of at least 0.90% carbon. The prestressing strand is manufactured by stranding the core wire and outer wires, giving a stretching treatment, and giving a bluing treatment at a temperature of 380&#xb0; C. or more and 430&#xb0; C. or less after or at the same time with the stretching treatment.

High-strength prestressing strand, method for manufacturing the same, and concrete construction using the same

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Itami, Japan

Takashi Ichiki