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Unbonded Steel Strand

big

Processing: Continuous drawing with big area reduction, stabilizing treatment and plastic coating
Features: High tensile strength, low relaxation, stable modulus of elasticity, stress-relieved
Standard: JC3006-93, Q/320281, PD05-2002
Application: Post-tensioned pre-stressed concrete structures

Implementing Standards and Main Technical Indicators
Implementing Standard
Specificationmm
Tensile Strength
MPa
Yield LoadKN
Modulus of Elasticity N/mm2

Weight of Anti-corrosion Lubricating Grease
g/m

More than
Thickness of the HDPE Jacket
mm
1000h Relaxation %,Initial Load: 70% of the Breaking load not more than
Relaxation Grade 1 Relaxation Grade 2
JG3006-932002
Q/320281PD05-2002
12.0
(12.7)
15.0
(15.20
15.24 )
1860

1860
166*

234*
1.8103

1.8103
43

50
≥0.8

≥0.8
8.0


8.0
2.5


2.5
 

Technical Standards for Products of Unbonded Pre-stressed Tendons

The unbonded pre-stressed tendons are mainly used in the post-tensioned pre-stressing systems. The difference between the unbonded pre-stressed tendon and the bonded pre-stressed tendon is that the unbonded one will not bond to the concrete surrounding it and will always allow the vertical and relative sliding between the pre-stressed tendon and the surrounding concrete during operation. The pre-applied force depends complete on anchors to be passed to the concrete. During construction, the unbonded tendons can be put into the formwoks just as normal reinforcing bars. After the concrete pouring step is finished and the concrete attains to a designed strength, the tensioning and anchoring work can be done. There is no need to reserve ducts and there is no need to carry out some steps such as grouting and etc. Therefore unbonded pre-stressed tendons have the following characteristics:
1. When a large pre-stressed slab is used, this product is very convenient for supporting formworks. There is no need to build formworks for internal columns and beams. At the same time, it is convenient to use big formworks for inner and outer surfaces, which speeds greatly the construction.
2. This product helps to save about 28% of reinforcing steel bars, about 6% of concrete usage and reduce the usage of formworks and the waste of transportation and working time.
3. The bars can be rapidly placed onto the pre-stressed slab, which avoids the step of drilling through the beam bars like in the normal beam-slab structures of reinforcement concrete. This decreases the construction difficulties.
4. Unbonded tendons have little friction and are easy to be bended into curves with various spans, which makes them suitable for structures with complicated and continuous curved reinforcing bars.
5. This product helps to expand the utilization area and increase the structural performance.
6. It is convenient for structural construction, upholstering and equipment installation.

7. The number of floors can be increased with same building height and interior net storey height.

Tension Test

Items
Specification
Steel Strand
1

Tensile Strength
Yield Strength 0.2 N/mm2 or Yield Load
Elongation %

N/mm2
KN
%
1860
166
3.5
1860
234
3.5

Bending Test

Number of bending tests not less than
Bend Radius R


mm
   Modulus of Elasticity
N/mm2
1.8103
1.8103

1000h Relaxation, % (the initial load is 70% of the breaking load)

Not more than
I级松弛
8.0
8.0
II级松弛
2.5
2.5
  Sectional Area
mm2
98.71
140
  Weight
Kg/m
0.7
1.09

Weight of Anti-corrosion Lubricating Grease, more than

g/m >
43
50
Thickness of the HDPE Jacket
mm
0.8
0.8

Friction Test

The friction coefficient between the unbonded pre-stressed tendons and the walls

Considering the influence on the friction coefficient by the local length deviation of every meter of unbonded pre-stressed tendon
0.12
0.004
0.12
0.004

Note: (1) * refers to the Yielding Load is 85% of the breaking load of the whole strand wire;

(2) As agreed by both Parties, it is permissible to supply pre-stressed steel rods of other strength and diameters based on different purposes.

 

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Product
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Address:No.679, Binjiang west road, Jiangyin City, Jiangsu Province,P.R.C  
pc: 214443  Tel: 0086-510-86402144
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