I. Introduction
Steel bridges are a vital component of modern transportation infrastructure. Due to prolonged exposure to atmospheric conditions, steel bridges face severe corrosion threats. A well-designed anticorrosive coating system is key to ensuring the design service life of the bridge.
II. Corrosion Environment Classification (ISO 12944)
Corrosion Level | Typical Environment | Carbon Steel Corrosion Rate
C1 (Very Low) | Indoor, dry environment | ≤1.3μm/year
C2 (Low) | Rural atmosphere | 1.3–25μm/year
C3 (Medium) | Urban/industrial atmosphere | 25–50μm/year
C4 (High) | Coastal/chemical plants | 50–80μm/year
C5 (Very High) | Heavy pollution/marine | 80–200μm/year
III. Design of Anticorrosive Coating System for Bridges
Taking the C4 environment as an example, a typical coating system includes:
Surface treatment: Abrasive blasting to Sa2.5 grade, roughness Rz 40–75μm
Primer (Zinc-rich epoxy): Dry film thickness 60–80μm, providing cathodic protection
Intermediate coat (Micaceous iron oxide epoxy): Dry film thickness 100–150μm, providing barrier protection and increasing coating thickness
Topcoat (Polyurethane/fluorocarbon): Dry film thickness 60–80μm, offering weather resistance, decoration, and protection of the underlying layers
Total dry film thickness: 220–310μm, design service life: 15–25 years.
IV. Kexin Bridge Anticorrosion Products
Kexin New Materials offers a full range of bridge anticorrosion coatings, which have been successfully applied in multiple key bridge projects. The products have passed testing 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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