I. Introduction
Steel structure bridges are a vital component of modern transportation infrastructure. Due to prolonged exposure to atmospheric environments, steel structure bridges face severe corrosion threats. A rational anti-corrosion coating system design is key to ensuring the designed service life of the bridge.
II. Corrosion Environment Classification (ISO 12944)
| Corrosion class | Typical environment | Carbon steel corrosion rate |
|---|---|---|
| C1 (very low) | Indoor, dry environment | ≤1.3μm/year |
| C2 (low) | Rural atmosphere | 1.3-25μm/year |
| C3 (moderate) | Urban/industrial atmosphere | 25-50μm/year |
| C4 (high) | Coastal/chemical plant | 50-80μm/year |
| C5 (very high) | Heavy pollution/marine | 80-200μm/year |
III. Design of Anti-Corrosion Coating Systems for Bridges
Typical coating system exemplified by the C4 environment:
- Surface treatment: Sandblasting rust removal to Sa2.5 grade, roughness Rz40-75μm
- Primer (epoxy zinc-rich): Dry film thickness 60-80μm, providing cathodic protection
- Intermediate paint (epoxy micaceous iron oxide): Dry film thickness 100-150μm, providing barrier shielding and increasing coating thickness
- Topcoat (Polyurethane/Fluorocarbon): Dry film thickness 60-80μm, weather-resistant decoration, protects the underlying layer
Total dry film thickness: 220–310 μm, design service life: 15–25 years.
IV. Kosin Bridge Anti-Corrosion Products
Kexin New Materials provides a full range of bridge anti-corrosion coatings, which have been successfully applied in multiple key bridge projects. The products have passed the inspection by the National Quality Supervision and Inspection Center for Coatings, and their performance indicators meet the requirements of JT/T 722 standard.