Mechanism Analysis of GRC Component Cracking Caused by Steel Bar Corrosion and Discussion of Influencing Factors

A building's durability begins with the reliability of its materials. As an important material in modern architectural decoration, GRC (glass fiber reinforced concrete) has long-term performance closely tied to structural safety. Rebar corrosion, a key cause of cracking in GRC components, not only affects architectural aesthetics but may also give rise to safety hazards. Drawing on Qinglong Group's 28 years of experience in GRC detailed design, manufacturing, and engineering practice, this article provides an in-depth analysis of the mechanism of rebar corrosion, systematically reviews the influencing factors, and proposes professional prevention and control solutions, offering full-chain technical support for designers and owners.

Mechanism of Rebar Corrosion in GRC Components: From Microscopic Degradation to Macroscopic Cracking

GRC components are a composite of cement-based materials, glass fibers, and a steel reinforcement skeleton. As the primary load-bearing element, the corrosion of the steel reinforcement is essentially the result of electrochemical reactions. When corrosive media such as moisture, carbon dioxide, and chloride ions in the air penetrate to the rebar surface and destroy the passive film, the steel undergoes oxidation to form rust (mainly Fe₂O₃·nH₂O). Rust expands to 2-6 times the volume of the original metal, and this expansion stress continuously acts on the surrounding GRC matrix. When the stress exceeds the tensile strength of the material, cracking occurs from the inside out. Through scanning electron microscopy, Qinglong's technical team found that early-stage corrosion appears as pitting on the rebar surface, gradually develops into general corrosion over time, and ultimately causes longitudinal cracks along the rebar within the component, accompanied by spalling of the protective cover in severe cases.

Multi-Dimensional Analysis of Influencing Factors: The Combined Effects of Environment, Materials, and Workmanship

1. Environmental Factors: Penetration Paths of Corrosive Media Humidity, temperature, and pollutants in the natural environment act as “catalysts” for corrosion. High-humidity environments provide the electrolyte for electrochemical corrosion, while chloride ions in coastal areas and sulfur dioxide in industrial zones accelerate the corrosion process. Accelerated aging tests at Qinglong's Nanning production base show that in environments with humidity >85% and chloride ion concentration >0.3%, the rebar corrosion rate is more than 3 times higher than in dry environments. In addition, freeze-thaw cycles aggravate microcracks in the GRC matrix, providing more penetration channels for corrosive media.

2. Material Properties: The Key Role of Cover and Impermeability The density of the GRC matrix and the thickness of the protective cover directly affect the effectiveness of corrosion protection. Qinglong's low water-binder ratio formulation (water-binder ratio ≤0.35) and special mineral admixtures keep matrix porosity below 15%, achieving an impermeability grade of P12. Meanwhile, strict enforcement of cover thickness standards (≥25mm for load-bearing rebar), combined with the crack-arresting effect of glass fibers, can effectively delay the penetration of corrosive media. Comparative tests show that GRC components made with Qinglong's patented formulation have a corrosion initiation time 2-3 times longer than those with ordinary formulations.

3. Construction Techniques: Attention to Detail Determines Long-Term Performance Rebar pretreatment during production (such as rust removal and galvanizing), vibration compaction, and curing regimes are crucial to corrosion protection. Qinglong has introduced automated production lines, using high-frequency vibration to ensure matrix density and steam curing (temperature 60-80°C, humidity ≥90%) to promote hydration reactions, increasing 28-day strength by more than 20%. Waterproofing of anchor nodes during installation is equally critical. Qinglong's sealant caulking technique can reduce the risk of rainwater penetration by more than 90%.

Qinglong's Full-Chain Solution: From Source Prevention to Smart Operation and Maintenance

As a national high-tech enterprise, Qinglong, guided by its mission of “Creating Beautiful Architecture,” has built a corrosion prevention and control system covering design, production, construction, and maintenance. In the design phase, BIM technology is used to simulate component loading and corrosive environments, optimizing rebar layout and cover design. In production, galvanized rebar or epoxy-coated rebar is used, combined with self-developed corrosion inhibitors, giving components a weathering service life of over 50 years. During construction, 3D laser scanning positioning is applied to ensure installation precision and sealing performance. In the after-sales phase, relying on a nationwide maintenance network, a regular inspection mechanism has been established (such as rebar corrosion potential testing and crack width monitoring), enabling early detection and early resolution of problems.

From the GRC curtain wall of the Dongguan Women and Children's Activity Center to the light-transmitting concrete project at Century Plaza on Nanjing East Road, Qinglong has consistently upheld the standard of “meticulousness and excellence,” deeply integrating material performance with engineering practice. Facing the industry-wide challenge of rebar corrosion, Qinglong, with 28 years of technical expertise and full-chain service capabilities, safeguards building safety and aesthetics while continuously driving the innovative application of GRC materials in high-end architecture.