ASTM A1055/A1055M-22

Overview

ASTM A1055/A1055M-22: Standard Specification for Zinc and Epoxy Dual-Coated Steel Reinforcing Bars defines the criteria for deformed and plain steel reinforcing bars coated with both zinc alloy and epoxy. Developed by ASTM International, this standard addresses enhanced corrosion resistance for steel reinforcing bars by specifying a dual-layer process: a zinc alloy layer using either a thermal spray or hot-dip galvanizing method, followed by an epoxy coating applied electrostatically. The document sets requirements for coating thickness, chemical composition, flexibility, adhesion, and continuity, supporting the use of these coated bars in demanding environments where durability and corrosion performance are critical.

Key Topics

• Dual Coating System: The standard specifically addresses reinforcing bars that use both a zinc alloy (applied via thermal spray or hot-dip process) and a fusion-bonded epoxy coating for optimal corrosion protection.
• Coating Types:
  • Type I: Zinc alloy applied by thermal spray coating
  • Type II: Zinc alloy applied in line with ASTM A1094/A1094M (hot-dip galvanizing)
• Material and Coating Requirements: Steel bars must conform to established ASTM specifications for reinforcing bars, while zinc and epoxy coatings must meet strict chemical composition and performance criteria.
• Coating Process Controls:
  • Surface preparation (cleanliness, profile, and inspection)
  • Application procedures for both zinc and epoxy layers
  • Quality control through measurements of thickness, flexibility, adhesion, and continuity
• Testing & Inspection:
  • Bend tests for evaluating coating flexibility
  • Thickness and holiday (defect) detection
  • Adhesion and durability testing
• Repair and Handling Guidelines: Specifies limits on repaired areas, methods for patching, handling to prevent damage, and storage recommendations to retain protective performance.
• Certification and Traceability: Requires written certification of compliance and traceable identification of all coated bars throughout processing and delivery.

Applications

Dual-coated steel reinforcing bars specified by ASTM A1055/A1055M-22 are primarily used in structural concrete applications where enhanced durability is required, especially in:

• Bridges and Highway Infrastructure: Exposure to deicing salts, marine environments, or chemically aggressive soils where corrosion of reinforcing steel is a concern.
• Coastal and Marine Structures: Piers, seawalls, and docks benefit from the dual coating’s superior resistance to saltwater-induced corrosion.
• Industrial and Chemical Facilities: Areas subject to chemical exposure where additional protection beyond a single-layer coating is desired.
• Tunnels and Underground Construction: Applications with high moisture exposure or aggressive groundwater.

By providing a synergistic protective system, the dual coating extends the service life of reinforced concrete structures, reduces maintenance needs, and supports overall sustainability and resilience in civil engineering projects.

Related Standards

For users and specifiers of ASTM A1055/A1055M-22, familiarity with these related ASTM and industry standards is valuable:

• ASTM A615/A615M: Standard Specification for Deformed and Plain Carbon-Steel Bars for Concrete Reinforcement
• ASTM A706/A706M: Deformed and Plain Low-Alloy Steel Bars for Concrete Reinforcement
• ASTM A775/A775M: Epoxy-Coated Steel Reinforcing Bars
• ASTM A1094/A1094M: Continuous Hot-Dip Galvanized Steel Bars for Concrete Reinforcement (relevant for Type II)
• SSPC-PA 2: Measurement of Dry Coating Thickness with Magnetic Gauges
• SSPC-SP 10: Near-White Blast Cleaning for surface preparation
• ACI 301: Specifications for Structural Concrete

Adhering to this standard ensures compliance with best practices for dual coated reinforcing bars and supports structural performance and durability in challenging conditions.

Keywords: ASTM A1055/A1055M, zinc and epoxy dual-coated, steel reinforcing bars, corrosion resistant rebar, thermal spray, hot-dip galvanizing, epoxy coated rebar, construction standards, reinforced concrete durability, dual coated steel.