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.

High carbon three-wire steel strand has stable structure and mainly used for bridges.

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 5224StructureNominal 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 A416GradeNominal diameterTolerance (mm)Cross-sectional area (mm2)Theoretical weight per 1000m (Kg/1000m)The minimum breaking forceThe 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.

High carbon steel strand has high tensile strength and low relaxation, so that it can be used as cables in bridge construction.

High carbon steel strand has high toughness and it is ideal for prestressing concrete.