Mechanism and Influencing Factors of Steel Corrosion-Induced Cracking in GRC Components

The vitality of a building lies hidden in the details of every material. When GRC components crack due to steel rebar corrosion, it is not merely an aesthetic loss, but a warning bell for structural safety.

In the field of modern architectural decoration, GRC (Glass Fiber Reinforced Concrete) has become the ideal choice for high-end projects such as grand theaters, commercial complexes, and landmark buildings, thanks to its advantages of light weight, high strength, and flexible shaping. However, the cracking of GRC components caused by steel rebar corrosion may quietly threaten a building's safety and durability. As an industry leader with 28 years of full-chain experience in UHPC/GRC/GRG/GRP materials, Qinglong Group will provide designers and owners with an in-depth analysis of this technical challenge from two aspects—the underlying mechanism and the influencing factors—along with professional solutions.

I. The Underlying Mechanism of GRC Component Cracking Caused by Steel Rebar Corrosion

The core advantage of GRC components lies in the synergy between glass fibers and concrete, while the embedded steel rebar further strengthens their structural performance. When the rebar corrodes, its volume expands by 2-6 times, generating enormous tensile stress. This stress first acts on the concrete layer surrounding the rebar; once it exceeds the tensile limit of the GRC material (typically 3-5 MPa), radial cracks develop from the inside out. They initially appear as fine hairline cracks, and as corrosion intensifies, the cracks gradually expand into through-going fractures, ultimately leading to reduced load-bearing capacity, surface spalling, and even safety hazards. During the detailed design phase, Qinglong Group uses BIM technology to simulate the stress state of the rebar, reducing corrosion risk at its source.

II. Analysis of the Three Key Factors Influencing Steel Rebar Corrosion

1. Material Mix Ratio and Manufacturing Process: The alkalinity of the cementitious matrix in the GRC material, the alkali resistance of the glass fibers, and the thickness of the rebar cover directly affect the corrosion rate. Qinglong's production base adopts customized mix ratio designs, strictly controls the water-cement ratio (≤0.45) and fiber content (≥4%), and ensures that deviations in cover thickness are kept within ±2mm, building a solid anti-corrosion barrier at the material level.

2. Environmental Erosion: Environmental factors such as moisture, chloride ions, and carbon dioxide are “catalysts” of corrosion. In coastal areas or industrial environments, accelerated chloride ion penetration destroys the passive film on the rebar surface, while carbonation lowers the alkalinity of the concrete and weakens its protective capacity. Qinglong GRC components are formulated with corrosion inhibitors and hydrophobic agents, achieving an impermeability grade of P10 or above to effectively resist environmental erosion.

3. Installation and Later-Stage Maintenance: Excessive bending of the rebar during installation, stress concentration caused by insecure anchoring, or a lack of later-stage maintenance will all accelerate corrosion. Qinglong holds a Grade II qualification for professional contracting of building curtain wall engineering; its construction team uses 3D laser scanning positioning technology to keep installation accuracy errors within ≤3mm, and provides 5 years of regular maintenance services to promptly identify and address potential corrosion issues.

III. Full-Chain Solutions: Qinglong's Practice from Prevention to Repair

As a National High-Tech Enterprise and a participant in the formulation of GRC industry standards, Qinglong Group has built a full-chain corrosion prevention and control system spanning “design-production-construction-maintenance.” In the design phase, parametric design is applied to optimize the rebar layout; in production, automated production lines and steam curing processes are used to enhance material density; during construction, the Technical Standard for Application of Glass Fiber Reinforced Cement (GRC) in Buildings (JGJ/T423-2018) is strictly implemented; and in the after-sales phase, RFID chips enable full life-cycle traceability of components. To date, among the 600+ GRC projects undertaken by Qinglong, over 95% have shown no corrosion-induced cracking for more than 10 years, testifying to the reliability of its technical solutions.

Although steel rebar corrosion is an “invisible killer” of GRC components, it is entirely preventable and controllable through scientific material selection, rigorous process control, and a sound maintenance system. Backed by 28 years of industry experience and always upholding the principle of “meticulousness and the constant pursuit of excellence,” Qinglong Group delivers GRC solutions for the architectural decoration industry that combine aesthetic value with structural safety, helping bring its mission of “creating beautiful buildings” to life. Choose professionalism, choose peace of mind—Qinglong joins you in building architectural beauty.