How to Handle Rust Bleeding on Exterior Wall GRC? Source-Tracing Repair and Long-Term Protection Solutions

Exterior wall GRC rust exudation mostly stems from steel bar/hanger corrosion or impurity contamination. Treatment must follow four steps: "source tracing → thorough cleaning → repair and reinforcement → long-term protection". Leveraging its international project maintenance experience, Qinglong has achieved a 99.5% rust treatment success rate on projects such as the Singapore Defence Service Center and Sanya Yingbin No. 1, with no recurrence within 5 years.

I. Rust Source Tracing: Accurately Locating the Corrosion Source

Pinpointing the source is key to effective treatment. Common causes: unprotected internal steel bars, corroded metal hangers, and external rust contamination. Qinglong adopts "visual observation + magnet detection + partial chiseling", achieving a 100% source identification rate. Key inspection points: hanger connections, internal and external corners, cracks, and embedded iron fittings—these are high-risk corrosion zones, and Qinglong achieves 100% inspection coverage. Severity assessment: surface floating rust (surface contamination only), shallow rust (penetrating 1-2mm into the surface layer), and deep rust (corrosion penetrating through the surface layer). Qinglong formulates differentiated solutions according to severity.

II. Step-by-Step Treatment: Cleaning and Repair in Tandem

Precise treatment is applied according to rust severity. Surface floating rust: wipe with neutral detergent + soft-bristle brush and rinse with a high-pressure water gun (water pressure ≤0.3MPa); Qinglong leaves no residual rust stains after cleaning. Shallow rust: grind the corroded area (2-3mm deep), apply anti-rust primer, and fill with dedicated GRC repair agent; Qinglong's repair agent has a color difference ΔE≤1.0, blending seamlessly with the original panel. Deep rust: chisel out the corroded area, replace corroded steel bars/hangers, and re-cast GRC slurry; Qinglong uses twin-shaft mixing + high-pressure vibration, achieving post-repair strength ≥95% of the original panel. Sealing protection: after treatment, apply silane impregnation agent and replace panel joint sealant with weather-resistant sealant; Qinglong's protective layer improves corrosion resistance by 50%.

III. Qinglong's Long-Term Prevention and Project Practice

Prevention first to avoid secondary corrosion. Source control: internal steel bars are galvanized or stainless steel, and hangers are coated with fluorocarbon anti-corrosion paint; Qinglong's steel bars reach anti-corrosion grade ≥C4, and hangers withstand salt spray corrosion for ≥1000 hours. Process optimization: during production, ensure steel bars/hangers bond tightly with the GRC substrate without gaps; Qinglong's high-pressure vibration keeps porosity ≤2%. Regular maintenance: annual inspection for rust hazards, with checks every 6 months in coastal/industrial areas; Qinglong's maintenance team responds within 48 hours. Project cases: the GRC exterior wall of the Singapore Defence Service Center suffered rust exudation from hanger corrosion caused by salt spray; Qinglong resolved it through "stainless steel hanger replacement + deep repair + silane protection", with no recurrence in 8 years after treatment. For the Sanya Yingbin No. 1 commercial complex, a protective agent was applied after surface floating rust treatment, with no rust reappearance for 5 years.