GRC Component Embedded Rebar Rust Prevention: Untreated After Welding, a 20-Year Safety Hazard Not to Be Ignored

Rebar is the "backbone" of GRC components, welding is the key process connecting this "backbone," and anti-rust treatment is the last line of defense protecting it. As a group with 28 years of experience in GRC detailed design and manufacturing, Qinglong Group has witnessed too many project cases where components aged prematurely and lost structural stability because embedded rebar was not rust-proofed after welding.

After welding, a high-temperature oxide layer forms on the surface of embedded rebar, while weld seams tend to retain welding slag and moisture. If the rebar is directly embedded in GRC components or exposed to air, rust problems will quietly develop. During its participation in the 120,000-square-meter GRC roof project of the Hainan International Convention and Exhibition Center, Qinglong found that rebar without anti-rust treatment shows obvious corrosion within just 3-5 years in humid environments, while properly treated rebar remains intact for more than 15 years.

Rust Spread: The "Invisible Destroyer" of GRC Components

Rusting causes rebar to expand in volume—by up to 2-3 times its original volume—and this expansion force acts directly on the surrounding GRC substrate. During maintenance work on the Dongguan Women and Children's Activity Center project, Qinglong's technical team found that welded rebar without anti-rust treatment, once corroded, splits GRC components from within, forming micro-cracks that are difficult to detect with the naked eye. These cracks gradually extend, ultimately leading to surface spalling and reduced strength of the components.

Structural Instability: From Local Damage to Overall Risk

The load-bearing capacity of GRC components depends on the coordinated action of rebar and the substrate. Corroded rebar loses its original tensile strength, and rust at weld seams can also cause connection failure. Qinglong once handled GRC curtain wall repairs for an old commercial building where, because embedded rebar was not rust-proofed after welding, some components suffered rebar fractures and loose connections—had they not been corrected in time, this could very likely have posed a risk of falling objects at height. For GRC landmark buildings with complex shapes such as the Wuhan Han Show Theatre, anti-rust treatment is even more critical, as it directly relates to the components' service life of more than 20 years.

Soaring Costs: Later Repairs Far Exceed Early Protection

The cost of anti-rust treatment for embedded rebar accounts for only 1%-3% of the total cost of GRC components, yet later repair costs caused by skipping rust-proofing can reach several times the value of the components. During maintenance of overseas projects, Qinglong found that replacing rusted rebar requires dismantling the original components and re-producing and re-installing them, which is not only time-consuming and labor-intensive but may also affect the normal use of the building. By following the Technical Standard for Application of Glass Fiber Reinforced Cement (GRC) in Building (JGJ/T423-2018) and adopting processes such as rust removal, anti-rust paint coating, and anti-corrosion tape wrapping, risks can be avoided at the source.

With 28 years of deep expertise in the GRC field, Qinglong has always maintained strict attention to detail throughout the entire chain. The anti-rust treatment of embedded rebar after welding may seem like a minor step, but in fact it concerns building safety and durability. As a company that participated in formulating GRC industry standards, we recommend that all projects strictly implement anti-rust processes, making the "backbone" of GRC components truly indestructible and safeguarding buildings.