High Carbon Steel Strand Wires for Prestressed Concrete

Prestressed Steel Strand - High Tensile & Low Relaxation
High carbon prestressed steel strand is twisted by 2, 3, 7 or 19 pieces of high tensile steel wires. After surface treatment, high carbon steel wire rods are cold drawn to steel wires, then according to the strand structure, twisting a certain number of steel wires into a strand, next is the stabilization process of eliminating stress. In order to extend the durability, the wires would have metallic or non-metallic coating like galvanization, and in order to increase the bond strength with concrete, the wires surface may have nicks. High carbon steel strands are mainly used for prestressed concrete structure.
Classification:
According the number of steel wires in a steel strand, it can be divided into two-wire strand, three-wire strand, seven-wire strand and nineteen-wire strand.
According to the surface morphology of the strand, it can be divided into smooth steel strand, nick steel strand, compacted steel strand and galvanized steel strand and so on.
Three-wire high carbon steel strands with black surface and their cross-section in the blue background show their structure.
High carbon three-wire steel strand has stable structure and mainly used for bridges.
An end high carbon steel strand and its cross-sectional picture show it was twisted evenly by 7 pieces of high carbon steel wires.
High carbon steel strand for prestressed concrete have high tensile strength and low relaxation.
Specifications:
Material: 77B, 82B.
Diameter range: 1.2mm - 36mm.
Standards: GB/T 5224, ASTM A416, BS 5896, JIS G3536, AS/NZS 4672, NBR-7483.
Surface: galvanized, un-galvanized, coated PVC/PE/NYLOY, nicked, smooth.
Style: 1×2, 1×3, 1×7 and 1×19.
Packing: Baling strip strapped, inner plastic cover, outer paper-plastic packing cloth.
Mechanics properties of steel strand - GB/T 5224
Structure Nominal Diameter (mm) Tolerance (mm) Cross-sectional area (S/mm2) Theoretical weight per 1000m (Kg/1000m) Tensile strength no small than (Mpa) Yield strength no small than (Mpa) Elongation no small than (%） 1000h Relaxation Rate not more than (%)
1×2 8.00 ＋0.25 －0.10 25.1 197 1470 1320 3.5 2.5
10.00 39.3 309 1570 1410
12.00 56.5 444 1720 1550
1×3 10.80 ＋0.20 －0.10 58.9 462 1860 1670
12.90 84.8 666 1960 1760
1×7 9.50 ＋0.40 －0.20 54.8 430 1720 1550
11.10 74.2 582 1860 1670
12.70 98.7 775 1960 1760
15.20 140 1101 1470 1320
1570 1410
1670 1500
1720 1550
1860 1670
1960 1760
17.80 191 1500 1720 1550
1860 1670
Mechanics properties of steel strand - ASTM A416
Grade Nominal diameter Tolerance (mm) Cross-sectional area (mm2) Theoretical weight per 1000m (Kg/1000m) The minimum breaking force The minimum load when elongate 1% Elongation (%) 1000h Relaxation Rate not more than (%)
In mm
250 0.375 9.53 ＋0.40 －0.40 51.61 405 89.0 80.1 3.5 2.5
0.438 11.11 69.68 548 120.1 108.1
0.500 12.70 92.90 730 160.1 144.1
0.600 15.24 139.35 1094 240.2 216.1
270 0.375 9.53 ＋0.65 －0.15 54.84 432 102.3 92.1
0.438 11.11 74.19 582 137.9 124.1
0.500 12.70 98.71 775 183.7 165.1
0.600 15.24 140.00 1102 260.7 234.6
Features:
High corrosion resistance with zinc coating.
High tensile strength.
Low relaxation.
High abrasion resistance.
Firm connection with concrete.
Good performance at elevated temperature.
High fatigue resistance.
Applications:
In the most post-tensioned prestressing and pre-tensioned prestressing projects, smooth steel strand is the most widely used prestressed steel. Compacted steel strand is mainly used for hoisting operation and nuclear power project. Galvanized steel strand is often used as tie bar and cable of bridges and also external prestressing projects.
Three-wire steel strands make up tough cables used for bridge construction.
High carbon steel strand has high tensile strength and low relaxation, so that it can be used as cables in bridge construction.
Seven high carbon steel strands in a girder box for bridge reinforcement.
High carbon steel strand has high toughness and it is ideal for prestressing concrete.