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7-Wire Low Relaxation Unbonded Prestressing Strand (0.5 inch)

7-Wire Low Relaxation Unbonded Prestressing Strand (0.5 inch)

Advanced Corrosion-Protected Infrastructure Grade. Engineered for modern post-tensioned slab systems and foundation engineering, our 0.5-inch 7-wire unbonded prestressed concrete steel strand features premium anti-corrosion grease and a robust HDPE/PP protective sheath, ensuring exceptional durability, low-relaxation performance, and certified compliance with global civil standards.

7-Wire Low Relaxation Unbonded Prestressing Strand (0.5 inch / 12.7mm) | Greased & Sheathed PC Strand

1. Technical Specifications & Metallurgical Data

​Designed for critical post-tensioned floor systems, parking structures, and ground anchors. Every coil adheres to stringent international mechanical benchmarks.

Technical Parameter

Specification Value

Governing Standard

Nominal Diameter

12.7 mm (0.500 inch / 1/2")

ASTM A416 / A416M

Strand Configuration

7-Wire (1 Center Wire + 6 Helical Outer Wires)

BS 5896 / ASTM A416

Nominal Cross-Sectional Area

98.7 mm² (0.153 in²)

ASTM A416

Specified Tensile Strength

1860 MPa (Grade 270)

ISO 6934-4 / ASTM A416

Minimum Breaking Load (MBL)

≥ 183.8 kN (41,300 lbs)

ASTM A416

Coating & Sheathing

Anti-Corrosion Grease + Extruded HDPE/PP Sheath

ASTM A960 / PTI Specs

Relaxation Class

Class 2 (Low Relaxation, Max 2.5% at 1000h)

JIS G3536

2. Core Engineering Advantages

· â€‹Superior Multi-Layer Corrosion Protection: Each strand is uniformly coated with specialized anti-corrosion grease and tightly encased in a seamless, high-density polyethylene (HDPE) sheath to prevent moisture and chemical attack.

· â€‹Optimized Low-Relaxation Performance: Advanced thermal-mechanical stabilization minimizes long-term stress loss, securing stable prestressing force retention over extended commercial lifecycles.

· â€‹Enhanced Flexibility in Construction: Unbonded tendons allow for easy stressing and positioning during construction, making them ideal for complex flat-slab and waffle-slab designs.

· â€‹Full Traceability & Certification: Manufactured under stringent ISO 9001 protocols. Each commercial shipment includes a detailed Mill Test Certificate (MTC) verifying mechanical performance and coating thickness.

​3. Industrial & Infrastructure Applications

​Engineered for modern high-load structural floor systems and geotechnical projects:

· â€‹Commercial & Residential Buildings: High-rise office buildings, multi-story parking structures, and flat-plate concrete floor systems.

· â€‹Industrial Structures: Large-span industrial floor slabs, foundations, and heavy-duty storage platforms.

· â€‹Geotechnical Engineering: Rock and soil anchor systems, slope stabilization, and foundation tie-backs.

​4. Frequently Asked Questions (FAQ)

​Q: What materials are used for the grease and protective sheath?

A: We use specialized microcrystalline wax-based anti-corrosion grease that remains stable across wide temperature ranges, encased in a tough, UV-resistant high-density polyethylene (HDPE) or polypropylene (PP) extrusion sheath meeting PTI specifications.

​Q: Do these unbonded strands comply with ASTM A416?

A: Yes. The base steel strand complies strictly with ASTM A416 Grade 270 (or equivalent international standards), while the protective coating and sheathing meet relevant PTI and ASTM requirements.

​Q: What is the standard packaging and container load?

A: Coils are securely strapped, wrapped in protective materials, and palletized to prevent damage to the plastic sheath during transit. A standard 20ft container loads approximately 20 to 27 metric tons.

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