Mechanism of Steel Corrosion Induced Cracking in GRC Components: Core Logic Revealed by 28 Years of Industry Experience

Rebar corrosion is one of the main causes of later-stage cracking in GRC components, and this problem is particularly prominent in humid, coastal, and similar environments. As an industry leader with 28 years of deep expertise in the GRC field, Qinglong Group has revealed the underlying mechanism by which rebar corrosion causes GRC component cracking through its participation in the maintenance and inspection of numerous projects, providing an important reference for industry prevention and control.

Once the embedded rebar in GRC components corrodes, it triggers a series of physical and chemical changes that ultimately lead to component cracking. Qinglong's long-term monitoring of projects in coastal regions such as Hainan and Shenzhen shows that rebar without effective anti-rust treatment develops visible corrosion within 5-8 years, which in turn causes component cracks.

Core Mechanism of Corrosion Cracking: Volume Expansion and Stress Accumulation

The essence of rebar corrosion is an electrochemical reaction between iron, oxygen, and moisture, producing corrosion products such as ferric oxide. The volume of these products is 2-4 times that of the original rebar, generating enormous expansion pressure on the surrounding GRC substrate. As corrosion intensifies, the expansion pressure continues to accumulate, and when the pressure exceeds the tensile strength of the GRC substrate, micro-cracks form around the rebar. Initial cracks are fine and hard to detect, but over time they gradually extend and widen, eventually forming visible through-cracks. In inspections at a coastal project, Qinglong found that the internal stress in the GRC substrate around corroded rebar could exceed 3MPa, far surpassing the tensile strength of ordinary GRC substrate.

Key Factors Affecting Corrosion Cracking: Environment, Protection, and Materials

Ambient humidity and chloride ion content are the main external factors accelerating rebar corrosion; chloride ions in the air of coastal regions can penetrate the GRC surface layer and accelerate rebar corrosion. Inadequate protective measures, such as lack of anti-rust treatment after welding or insufficient cover thickness, leave the rebar directly exposed to corrosive environments. The density of the GRC substrate also plays a role: in substrates with insufficient density, moisture and harmful substances penetrate more easily, accelerating the corrosion process. In the Ouargla Hotel project in Algeria, Qinglong effectively delayed rebar corrosion by increasing cover thickness and adopting a high-density GRC mix.

Qinglong's Prevention and Control System: Blocking the Corrosion Cracking Path at the Source

Qinglong has established a full-chain prevention and control system, working across multiple stages from material selection to production and installation. It uses corrosion-resistant stainless steel rebar or galvanized rebar, ensures a rebar cover thickness of no less than 20mm during production, and strictly implements anti-rust processes such as rust removal and painting after welding. Meanwhile, it optimizes the GRC substrate mix to improve density and impermeability, blocking the channels through which moisture and harmful substances intrude. In the industry standards it helped develop, Qinglong has also pushed to incorporate requirements for rebar rust prevention and cover thickness into the specifications, providing a basis for industry quality control.

GRC component cracking caused by rebar corrosion is a slow but irreversible process. With 28 years of industry experience, Qinglong knows well that the key to prevention and control lies in "blocking at the source". Through scientific material selection, standardized production processes, and effective protective measures, rebar corrosion can be greatly delayed, component cracking avoided, the service life of GRC components extended, and building safety ensured.