NABL Accredited · Metal Testing Service
Zinc and Zinc Alloy Coated Prestressed Strand Testing
(ASTM A856 — Galvanised Strand)
Mechanical and coating quality testing of zinc and zinc alloy (Zn-5Al) coated prestressed wire strands — verifying coating mass, adherence and mechanical properties for corrosion-resistant prestressed applications.
ASTM A856
Standard
±1%
Accuracy
5 Days
Report TAT
NABL
Accredited
NABL Accredited Lab · ISO/IEC 17025:2017
Digital Reports via Autovity QLMS
Pan-India · 7 Lab Locations
Est. 2009 · 20,000+ Projects
Overview
What is the Zinc and Zinc Alloy Coated Prestressed Strand Testing?
Zinc and Zinc Alloy Coated Prestressed Strands use hot-dip galvanising or Zn-5Al (galfan) coating to provide sacrificial cathodic corrosion protection to prestressing wires — offering an economical intermediate corrosion protection level between uncoated and epoxy coated strand.
At Global Lab, testing per ASTM A856 covers coating mass (minimum 275 g/m²), coating adherence (wrapping test without flaking), mechanical properties (breaking load, 1% proof load, elongation per ASTM A416) — providing complete quality certification for galvanised strand acceptance.
Coating Mass Verification
Minimum 275 g/m² zinc coating mass per ASTM A856 confirmed.
Coating Adherence Test
Wrapping test — coating must not flake on tight coil bend.
Breaking Load & Proof Load
Mechanical properties meet ASTM A416 grade requirements.
Zn-5Al Galfan Testing
Both hot-dip zinc and Zn-5Al alloy coated strands tested.
NABL Certified Reports
All results on NABL-accredited letterhead per ASTM A856.
Relaxation Testing
1000-hour or 120-hour relaxation available alongside standard tests.
Test in Action
Zinc and Zinc Alloy Coated Prestressed Strand Testing — Site Images
Acid Dissolution for Coating Mass Measurement
Wrapping Adherence Test on Mandrel
Tensile Test of Zinc Coated Strand
Test Procedure
How the Zinc and Zinc Alloy Coated Prestressed Strand Testing is Conducted
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1Coating Mass MeasurementZinc coating dissolved in acid. Mass per unit area calculated from mass loss per ASTM A856.
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2Coating Adherence TestStrand sample wrapped tightly around mandrel 5 turns. Coating inspected for flaking.
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3Mechanical Test SetupStrand gripped in UTM with appropriate grips. Load applied at controlled rate.
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4Breaking Load & Proof LoadUltimate breaking load and 1% proof load measured per ASTM A416 grade requirements.
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5ASTM A856 ReportCoating mass, adherence and mechanical results vs ASTM A856. NABL report within 5 days.
Standards & Specifications
Applicable Test Standards
| Standard | Title | Scope | Type |
|---|---|---|---|
| ASTM A856 | Standard Specification for Zinc-Coated (Galvanized) Steel Wire Strand | Zinc Coated Strand | ASTM |
| ASTM A416 | Standard Specification for Low-Relaxation Seven-Wire Strand for Prestressed Concrete | Base Strand | ASTM |
| IS 6006 | Specification for Uncoated Stress Relieved Strand for Prestressed Concrete | Strand Reference | Indian Standard |
| EN 10138 | Prestressing Steels — Part 3: Strand | European Standard | European Standard |
Applications
Where is the CAPO Test Used?
Road bridge post-tensioning in moderate to severe chloride environments
Prestressed concrete piles for marine and coastal construction
External post-tensioned tendons on bridges in aggressive exposure classes
Prestressed concrete sleepers for railway track in corrosive environments
Precast prestressed elements for water treatment and sewage structures
Cable-stayed bridge stay cables in marine and coastal projects
Why Choose Global Lab
Our Advantages
NABL Accredited ReportsLegally valid ASTM A856 certificates for project acceptance.
Coating Mass AccuracyGravimetric method gives precise coating mass to ±5 g/m².
Zn-5Al Galfan CapabilityBoth standard zinc and premium Zn-5Al alloy coated strands tested.
Fast 5-Day ReportComplete ASTM A856 report within 5 working days.
Pan-India CoverageMetal testing at all 7 NABL-accredited lab locations.
Combined Strand PackageZinc + Epoxy coated + Standard strand testing offered together.