PC strand with low relaxation and high tensile

PC strand with low relaxation and high tensile

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Payment Type:	T/T
Incoterm:	FOB,CFR,CIF
Transportation:	Ocean
Port:	Tianjin Xingang

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Product Description

Product Attributes

Brand: Chunpeng

Standard: Aisi, Astm, Bs, Jis

Place Of Origin: China

Application: Construction

Whether Alloy: Non-Alloy

Packaging & Delivery

Selling Units	:	Ton
Package Type	:	The roll is wrapped in three layers of waterproof packaging, the roll eyes are facing up and two fumigated sleepers are tied to the bottom with steel belts.
Picture Example	:

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Product Description

Low Relaxation and High Tensile PC Strand: Comprehensive Product Introduction and Applications

1. Product Definition and Core Advantages

A low relaxation and high tensile PC strand (Prestressed Concrete Strand) is a high-performance reinforcing material for prestressed concrete, composed of multiple high-strength steel wires. It integrates two key features:

Low Relaxation: Extremely low stress decay rate under long-term loading (1000-hour relaxation rate ≤2.5%, vs. 8%-10% for ordinary strands), ensuring persistent prestress stability.
High Tensile Strength: Standard tensile strength ≥1860MPa (e.g., Grade 1860), reaching up to 1960MPa, 4-5 times that of ordinary steel bars, significantly reducing steel consumption.

2. Technical Parameters and Performance Indicators

Item	Technical Parameters	Testing Standards
Structure	Common 7-wire stranding (1×7 structure), diameter range 12.7mm-15.2mm; customizable (e.g., 1×19 structure)	GB/T 5224/ASTM A416
Tensile Strength	≥1860MPa (ultimate tensile strength up to >2000MPa)	Tensile Test (GB/T 228.1)
Yield Strength	≥1670MPa (approx. 90% of tensile strength)	Yield Strength Test
Relaxation Property	Relaxation rate ≤2.5% after 1000 hours under 70% of nominal tensile strength	GB/T 10120/ASTM A353
Elastic Modulus	(1.95-2.05)×10⁵ MPa	Elastic Modulus Test
Elongation	≥3.5% (gauge length 500mm)	Elongation after Fracture Test
Surface Treatment	Optional: plain, galvanized (Zn≥300g/m²), epoxy coating, non-bonded sheath, etc.	Surface Quality Inspection

3. Key Production Processes and Technical Breakthroughs

Raw Material Control:
- Adopts 82B high-carbon steel wire rod (C content 0.80%-0.85%), with S/P impurities ≤0.02% to ensure purity.
- Multi-pass cold drawing of steel wires refines grain structure to enhance strength.
Heat Treatment Optimization:
- Patenting Process: Steel wires are austenitized and quenched in a 450-550℃ lead bath to form sorbite structure, balancing strength and toughness.
- Stabilization Treatment: After stranding, apply 30%-50% of tensile strength at 200-400℃ to eliminate residual stress and reduce relaxation.
Surface Protection Technology:
- Hot-dip galvanizing forms a zinc-iron alloy layer, extending corrosion resistance to over 50 years.
- Epoxy coating via electrostatic spraying (thickness ≥0.3mm) suits harsh environments (marine, chemical, etc.).

4. Typical Application Scenarios and Engineering Cases

1. Bridge Engineering: Core Support for Long-Span Structures

Applications: Stay cables for cable-stayed bridges, suspension cables for suspension bridges, prestressed tendons for continuous beams.
Case Studies:
- Hong Kong-Zhuhai-Macao Bridge Immersed Tube Tunnel: Uses 1860MPa low-relaxation strands in prestressed systems to resist seawater corrosion and long-term loading.
- Hangzhou Bay Cross-Sea Bridge: Over 100,000 tons of strands reduce prestress loss, ensuring a 200-year design life.

2. High-Rise and Supertall Buildings

Applications: Foundation piles, transfer girders, shear wall edge components.
Case Study: Shanghai Tower (632m) uses 1960MPa strands in core wall prestressing to minimize concrete cracking and enhance seismic performance.

3. Water Conservancy and Energy Projects

Applications: Dam bodies, nuclear power plant containment structures, wind turbine foundations.
Case Studies:
- Three Gorges Dam spillway sections: Strands anchor gate piers to resist high water pressure.
- Nuclear containment ring prestressing: Double-layer anti-corrosion strands (galvanized + sheath) meet nuclear safety durability requirements.

4. Special Structures and Industrial Buildings

Applications: Circular prestressing for large oil tanks, crane beams in long-span factories, stadium domes.
Case Study: National Speed Skating Oval ("Ice Ribbon") for Beijing 2022 Winter Olympics: Low-relaxation strands enable a 70m column-free span in the roof cable network.

5. Comparative Advantages over Traditional Materials

Comparison Dimension	Low Relaxation & High Tensile PC Strand	Ordinary Strands/Steel Bars
Material Efficiency	30%-50% less steel consumption for the same load capacity	Higher steel usage, heavier structure
Construction Efficiency	Single tension length up to >100m, reducing joints	Limited tension length, stress concentration at joints
Long-Term Maintenance Cost	Low relaxation rate (≤5% stress loss in 20 years), long maintenance cycle	10%-15% stress loss in 10 years, frequent monitoring needed
Environmental Adaptability	Galvanized/coated for harsh environments (marine, chemical)	Plain bars require additional corrosion protection

6. Selection and Procurement Guidelines

Key Parameter Confirmation:
- Choose strength grade (1860MPa/1960MPa) based on design load.
- Select surface treatment (plain/galvanized/coated) according to environmental conditions.
- Verify relaxation rate for special scenarios (e.g., ≤1.5% for nuclear projects).
Certifications and Standards:
- Domestic projects: Comply with GB/T 5224-2014; international projects: Refer to ASTM A416 or EN 10138.
- Require suppliers to provide third-party test reports (tensile, relaxation, bend tests).
Supplier Recommendations:
- Leading domestic enterprises: Tianjin Steel Strand, Far Eastern 泓昇，Shandong Shengtong.
- International brands: Bridon Bekaert, VSL, Freyssinet.

7. Industry Development Trends

Higher Strength and Lower Relaxation: Developing 2000MPa-grade strands with target relaxation rate ≤1.0% for ultra-deep foundations and space construction.
Intelligent Integration: Embedded fiber optic sensors in strands for real-time stress and corrosion monitoring, promoting smart infrastructure.
Green Production: Replacing lead bath quenching with electric heating to reduce heavy metal pollution, aligning with carbon neutrality goals.
Chunpeng Group is a leading and professional manufacturer of prestressed concrete (PC) steel materials, with over 30 years of industry experience.

We are committed to delivering high-quality products and innovative solutions for infrastructure and construction projects worldwide.

Our Core Products are pc steel strand (Ultra High Tensile Strength PC Strand, Normal Tensile Strength PC Strand), Unbonded PC Strand, Galvanized PC Steel Strand, Weather-Resistant & Anti-Corrosion PC Strand, and PC Steel Wire.

In addition to our PC strand products, we also supply Prestressed Anchorage Systems and Photovoltaic Mounting Systems.