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Epoxy coated PC Strand is a specialized prestressed concrete steel strand with a protective epoxy resin layer, enhancing corrosion resistance in demanding environments. It builds on standard PC Strand by adding a durable barrier against moisture and chemicals.[page:0 from prior] This blog covers its definition, production, benefits, applications, and selection tips.
PC Strand consists of seven high-strength steel wires twisted together, typically low-relaxation per ASTM A416, with tensile strengths from 1725 to 1860 MPa.[ from prior] Diameters range from 9.5mm to 17.8mm, used in prestressing to compress concrete and counter tensile loads.
Epoxy coating modifies this base product for superior longevity, especially where uncoated strands risk rust from chlorides in de-icing salts or seawater.
The coating process applies fusion-bonded epoxy resin, typically 0.2-0.4mm thick (30 mils over wire crowns), filling voids between wires completely. Options include smooth (non-bonded), grit-embedded for bond enhancement, or filled for maximum protection.
Standards like ASTM A882 govern specs, ensuring coating adhesion, flexibility, and no impact on tensile properties. Unlike galvanized strand, epoxy provides a seamless, non-porous shield resistant to fretting fatigue during stressing.
Production starts with drawing high-carbon wires, stress-relieving, and stranding per A416. Wires then undergo:
Abrasive cleaning to remove oxides.
Electrostatic epoxy powder application.
Heating to 250-300°C for fusion bonding.
Cooling and grit impregnation if needed.
Quality checks for thickness uniformity and holidays (pinholes).
This yields a glossy, tough finish that withstands construction handling without cracking.
Epoxy coated strand outperforms uncoated in corrosive settings by preventing ingress of water, salts, and oxygen. Benefits include:
Corrosion Resistance: Extends service life 2-3x in chloride-rich areas; fully filled voids block internal rust.
Durability: Tough enough for site abuse; resists abrasion during duct insertion.
Bond Performance: Grit variants match or exceed uncoated pull-out strength (e.g., 14.27 kips vs. 10.45 kips).
Low Maintenance: Reduces strand failures in bridges, cutting repair costs.
No Strength Loss: Retains full tensile load and relaxation specs (<2.5%).
Studies show epoxy strand halves corrosion rates in simulated bridge decks.
Ideal for harsh-exposure prestressed elements:
Bridge Girders/Decks: Protects against de-icing salts; used in segmental and pretensioned designs.
Parking Structures: Shields from road salts and moisture cycles.
Marine/Piling: Resists seawater corrosion in docks and anchors.
Stay Cables: Enhances wind/rain resistance in cable-stayed bridges.
Post-Tension Slabs: For industrial floors with chemical spills.
US projects like San Francisco bridge widenings employed it extensively for pretensioned girders.
Application | Coating Type | Key Benefit |
Bridge Decks | Smooth/Filled | Chloride barrier |
Stay Cables | Grit-Embedded | Fretting fatigue resistance |
Piling | Filled | Marine corrosion protection |
Parking Slabs | Smooth | Salt/moisture shield |
Ground Anchors | Grit | Bond + durability |
Handle like uncoated strand but with care to avoid coating damage:
Use padded reels; limit coil drops.
Lubricate ducts with wax for smooth insertion.
Stress at ambient >5°C; max concrete cure temp 65°C to prevent bond issues.
Patch cut ends with epoxy compound; protect anchors.
For pretensioning, detension after 18-24 hours; grit aids transfer length.
Pull-out tests confirm 20-30% higher bond in grit-coated vs. smooth.
ASTM A882 mandates:
Coating thickness: 0.38-0.89mm average.
Adhesion: >1500 psi cut-through.
Flexibility: No cracks after 180° bend.
Electrical: <12 holidays per 1.8m.
ISO 14655 and JSCE add global benchmarks for filled epoxy. Field tests include cathodic protection compatibility and long-term exposure.
Type | Corrosion Protection | Bond Strength | Cost Premium | Best For |
Uncoated | Low | High | Baseline | Dry interiors |
Galvanized | Medium | Medium | +20% | Mild exposure |
Epoxy Coated | High | High (grit) | +50-100% | Bridges/parking |
Filled Epoxy | Very High | Variable | +80% | Marine/extreme |
Epoxy excels in dynamic, chloride-laden environments over wax or PE sheathing.
Higher cost offsets with lifecycle savings; slippery smooth coating needs anchors designed for low friction. Patching exposed ends prevents galvanic corrosion. Advances include UV-stable epoxies for above-ground cables.
Hybrid nano-epoxy coatings promise 50% better adhesion; self-healing variants detect breaches. Larger diameters (18mm+) gain epoxy for mega-structures.[prior ] Demand rises with infrastructure resilience mandates.
TJ Wasungen supplies epoxy coated PC Strand in standard diameters, compliant with ASTM A882/A416, for global projects.[prior page:1] Uniform coating ensures reliability; contact via WhatsApp +86-13622011252 or sales@tjwasungen.com.
