GRC Curtain Wall to Steel Structure Connection Anti-Rust Treatment Method? Qinglong GRC Connection Anti-Rust Core Technology

The connection nodes between the GRC curtain wall and the steel structure are the weak points in rust prevention. Corrosion not only weakens the connection strength; the products of rust expansion may also split open the GRC matrix. A strategy of "multiple protection and systematic isolation" must be adopted, with comprehensive anti-corrosion treatment applied to the connectors themselves, the connection interfaces, and possible water seepage channels. Qinglong GRC has established graded and classified rust-proofing treatment standards for different environmental and structural requirements.

In an irregular GRC curtain wall project for a marine-themed pavilion in Qingdao, the main structure was a complex spatial steel structure with more than five thousand connection points, located in the splash zone. Qinglong adopted the highest-grade "triple active protection + monitoring" scheme: first, all steel connectors (anchors and transition pieces) were hot-dip galvanized (average thickness 86μm) and then treated with the Dacromet process (chromium-free zinc-aluminum coating); second, two coats of epoxy zinc-rich primer were applied over the coating for sealing; third, after installation, flexible sealant was applied at the contact edges between the steel components and the GRC to block water vapor. Meanwhile, corrosion monitoring plates were embedded at key locations. When opened for inspection three years later, the connectors were as good as new.

Pretreatment of Connector Base Materials and Long-Lasting Plating (Coating)

Rust prevention must start with the base material. After fabrication, all steel connectors must undergo sandblasting or shot blasting for rust removal, reaching the Sa2.5 standard to thoroughly eliminate mill scale and rust traces. The protection process is then selected according to the environmental corrosion class (C1-C5): in general environments (C3), hot-dip galvanizing (thickness ≥55μm) may be used; in highly corrosive environments (C4-C5), the "hot-dip galvanizing + sealing coating" or "Dacromet" process must be adopted. Dacromet (chromium-free zinc-aluminum coating) offers excellent corrosion resistance (salt spray resistance of over 1,000 hours) with no risk of hydrogen embrittlement, making it particularly suitable for high-strength bolts.

Damage Protection and Sealing Treatment During Installation

No matter how good the coating is, it may be scratched during transport and installation. Therefore, after installation, secondary anti-corrosion sealing must be applied to all connectors, especially at points where the coating is damaged, such as welding spots, cut surfaces, and bolt heads. Zinc-rich primer or epoxy resin should be carefully applied to ensure the metal is completely covered by the coating, leaving no "pinholes".

Electrochemical Isolation and Drainage Design

When embedded steel parts in GRC (such as steel plates and threaded rods) need to be connected to exposed aluminum alloy anchors or stainless steel bolts, insulating gaskets (usually nylon or engineering plastic) must be placed between the different metals to prevent electrochemical corrosion caused by potential differences. The design of connection nodes must avoid water accumulation; drainage holes should be provided so that any seeping water can be discharged promptly.

Regular Inspection and Maintenance Plan

Rust-proofing treatment is not a one-and-done solution. A long-term inspection and maintenance plan should be established. Representative connection points may be opened for inspection every 3-5 years to assess the corrosion condition. For key areas such as coastal regions, a coating thickness gauge can be used to periodically check the coating thickness of exposed connectors to ensure protection effectiveness.

Connection rust prevention is the "lifeline" of GRC curtain wall safety. Qinglong GRC adheres to the principles of "prevention first, multiple lines of defense, and meticulous construction". Its rust-proofing system has withstood the long-term test of numerous major projects, ensuring that the connection system lasts as long as the main building structure.