How to Control the Thickness of the Steel Reinforcement Cover in GRC? Qinglong GRC Anti-Corrosion Technical Standard

The thickness of the steel reinforcement cover in GRC is a key parameter for ensuring long-term durability and must be scientifically determined based on environmental conditions and design service life. Based on extensive engineering practice, Qinglong GRC has established a complete cover control system.

In a seaside commercial complex project in Qingdao, Qinglong GRC applied differentiated cover design for different areas: a cover thickness of 25mm for outdoor components, 15mm for indoor dry environments, and 30mm for components in the splash zone. This tiered protection has proven highly effective over 10 years of verification: the reinforcement corrosion rate of splash-zone components was only 0.2%, far below the 3% warning threshold. Precise control of cover thickness was achieved through custom plastic spacers, with thickness tolerance controlled within ±1mm.

Environmental Exposure Classes and Corresponding Thicknesses

Indoor dry environment: 15mm; general outdoor environment: 20mm; coastal atmospheric zone: 25mm; splash zone: 30mm; de-icing salt environment: 35mm. This tiered approach ensures the reinforcement does not corrode over a 50-year service period.

Construction Precision Control Measures

High-strength plastic spacers are used at spacing not exceeding 500mm. After reinforcement tying, 3D scanning is performed and areas with deviation greater than 3mm are adjusted. A dedicated cover thickness acceptance inspection is carried out before pouring, with a required pass rate of 100%.

Quality Inspection and Acceptance Standards

Cover thickness is tested using the radar method or the destructive method, with a sampling ratio of no less than 5% of the components. The allowable deviation is +3mm and -1mm, with a required pass point rate of over 90%. Inspection records are established and the data is traceable.

Enhanced Protection for Special Areas

An additional 5mm of cover is applied to vulnerable areas such as component edges and corners. Dedicated sealing materials are used around embedded parts for enhanced protection. Multiple waterproofing measures are provided at joints to prevent water migration.

Cover thickness control requires refined management throughout the entire process. Through design optimization, construction control, and strict inspection, Qinglong GRC ensures the long-term durability of steel reinforcement.