What Are the Consequences of No Anti-Rust Treatment After Welding Embedded Rebar? — Qinglong Group's Analysis of Corrosion Hazards and Preventive Measures

If embedded rebar is not given anti-rust treatment after welding, serious durability and safety problems will arise. Based on 28 years of engineering practice and extensive case studies, Qinglong Group holds that untreated welded areas can trigger a chain reaction of rebar corrosion, cracking of concrete along the rebar, reduced structural load-bearing capacity, and even component failure, and must be taken very seriously.

Welded areas become starting points of corrosion. The welding process destroys the passivation film on the rebar surface, forming electrochemical corrosion cells in which the weld points act as anodes that accelerate corrosion. Accelerated tests in Qinglong Group's laboratory show that untreated weld points develop obvious corrosion within 3 months in humid environments, with corrosion depth reaching 0.5mm after 6 months. In an early project, anti-rust treatment was omitted due to oversight; an inspection 5 years later found severe corrosion in the welded areas, forcing large-scale strengthening, and the repair cost was 20 times the initial anti-rust investment.

Expansion of corrosion products causes concrete cracking. After corrosion, rebar volume expands 2-6 times, generating enormous expansion stress. During inspection of the Wuhan Han Show Theater project, Qinglong Group found that when the corrosion rate reaches 1%, cracks appear in the concrete along the rebar; when the corrosion rate exceeds 5%, crack widths exceed 0.3mm, severely affecting durability. This cracking not only spoils the appearance but also provides fast channels for moisture and corrosive media, accelerating a vicious cycle.

Structural load-bearing capacity declines significantly. Corrosion reduces the effective cross-section of the rebar and degrades bond performance. Test data show that when the cross-section loss rate reaches 10%, rebar yield strength drops by more than 15%; when corrosion causes cross-section loss exceeding 20%, component load-bearing capacity may drop by more than 30%. In extreme cases, local failure may occur, threatening overall safety.

Preventive measures are systematic and necessary. Immediately after welding, Qinglong Group performs mechanical rust removal (to Sa2.5 grade), applies an epoxy zinc-rich primer (dry film thickness ≥80μm), and finally wraps the area with polymer mortar. A welding procedure qualification system has been established to ensure every welder masters the anti-rust essentials. This full-process control reduces corrosion risk to a minimum.