1. Introduction
Steel structure bridges are a vital component of modern transportation infrastructure. Due to prolonged exposure to atmospheric conditions, these bridges face significant corrosion threats. A well-designed anti-corrosion coating system is essential to ensure the design service life of the bridge.
2. Corrosion Environment Classification (ISO 12944)
| Corrosion Level | Typical Environment | Carbon Steel Corrosion Rate |
|—————-|———————|—————————-|
| C1 (Very Low) | Indoor, dry environment | ≤1.3 μm/year |
| C2 (Low) | Rural atmosphere | 1.3–25 μm/year |
| C3 (Medium) | Urban/industrial atmosphere | 25–50 μm/year |
| C4 (High) | Coastal/chemical plants | 50–80 μm/year |
| C5 (Very High) | Heavy pollution/marine | 80–200 μm/year |
3. Design of Anti-Corrosion Coating System for Bridges
Taking the C4 environment as an example, a typical coating system includes:
– **Surface preparation**: Abrasive blasting to Sa2.5 level, with roughness Rz 40–75 μm
– **Primer (Zinc-rich epoxy)**: Dry film thickness 60–80 μm, providing cathodic protection
– **Intermediate coat (Micaceous iron oxide epoxy)**: Dry film thickness 100–150 μm, offering barrier protection and increasing coating thickness
– **Topcoat (Polyurethane/Fluorocarbon)**: Dry film thickness 60–80 μm, providing weather resistance, aesthetics, and protection for the underlying layers
– **Total dry film thickness**: 220–310 μm
– **Design service life**: 15–25 years
4. Kexin Bridge Anti-Corrosion Products
Kexin New Materials offers a full range of bridge anti-corrosion coatings, which have been successfully applied in numerous key bridge projects. The products have passed inspections by the National Coating Quality Supervision and Inspection Center, with performance indicators meeting the requirements of the JT/T 722 standard.
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