Scientific Control Methods for Reinforcement Cover Thickness in GRC

The thickness of the steel reinforcement protective cover in GRC directly affects the durability and safety of the structure. Based on 28 years of engineering experience, Qinglong Group believes that the cover thickness must be precisely controlled according to environmental class and component type, typically maintained within a range of 15-25mm, with multiple technical measures used to ensure thickness accuracy.

The setting of cover thickness must take environmental corrosivity into account. Qinglong Group classifies environments into three levels: general, humid, and corrosive. In the Wuhan Han Show Theatre project, the cover thickness for indoor dry environments was set at 15mm, while the coastal environment of the Hainan International Convention and Exhibition Center required an increase to 25mm. This differentiated design extends the time for chloride ions to penetrate to the steel reinforcement surface to more than 50 years.

Thickness control must start at the production stage. Qinglong Group uses a customized spacer system in which the strength of plastic spacers matches the GRC matrix, preventing the formation of weak points. In the Shenzhen Pingshan High-tech Zone project, 3D laser scanning positioning kept cover thickness deviations within ±2mm. Meanwhile, the vibration process was optimized to prevent spacer displacement, ensuring that the steel reinforcement mesh always remains in its design position.

Ensuring thickness during construction is equally critical. Qinglong Group uses non-metallic positioning fixtures during installation to avoid the risk of galvanic corrosion. In the Nanning Liyuan Hotel project, BIM model simulations allowed the cover thickness at complex joints to be adjusted in advance, ensuring continuity at bent sections. After completion, radar detection devices were used for spot checks, achieving a thickness pass rate above 98%.

Cover thickness is optimized in synergy with material performance. The high-density GRC mix developed by Qinglong Group enables a 15mm cover to achieve the protective effect of a conventional 25mm cover. This systematic thickness control method provides a solid guarantee for the long-term durability of GRC structures.