High-strength prestressing strand, method for manufacturing the same, and concrete construction using the same
View Patent ↗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 mm 2 or 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±0.3 mm and a diameter of the outer wires is 5.15±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° C. or more and 430° C. or less after or at the same time with the stretching treatment.
1. A high-strength prestressing strand having a seven-wire structure in which one core wire and six outer wires are stranded,
wherein 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 mm 2 or more, a load at 0.2% permanent elongation is 266 kN or more,
wherein a relaxation value measured after a 1000-hour relaxation test is 2.5% or lower,
wherein a diameter of the core wire is 5.35±0.3 mm and a diameter of the outer wires is 5.15±0.25 mm,
wherein the core wire and the outer wires each comprise a carbon concentration of 0.90% or more, and
wherein 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° C. or more and 430° C. or less after or at the same time with the stretching treatment.
2. A concrete construction using a high-strength prestressing strand according to claim 1 .
3. A method of manufacturing a high-strength prestressing strand having a seven-wire structure in which one core wire and six outer wires are stranded, comprising:
stranding the core wire and outer wires;
giving a stretching treatment; and
giving a bluing treatment at a temperature of 380° C. or more and 430° C. or less after or at the same time with the stretching treatment,
wherein 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 mm 2 or more, a load at 0.2% permanent elongation is 266 kN or more,
wherein a relaxation value measured after a 1000-hour relaxation test is 2.5% or lower,
wherein a diameter of the core wire is 5.35±0.3 mm and a diameter of the outer wires is 5.15±0.25 mm, and
wherein the core wire and outer wires each comprise a carbon concentration of 0.90% or more.