What Treatments Need Strengthening for GRC Decorative Panels in Humid Environments?

A humid environment poses a severe challenge to the durability of GRC decorative panels, requiring systematic protective measures. Drawing on experience from coastal projects such as the Hainan International Convention and Exhibition Center, Qinglong Group has developed a three-in-one protection system combining material modification, structural design, and surface treatment.

Material modification is the foundation of protection. Qinglong Group uses low-alkalinity cement (alkali content ≤0.6%) and alkali-resistant glass fibre with a zirconium content above 16%, improving moisture resistance at the source. Silica fume (10%-15%) and slag powder (20%-30%) are added to the mix design to keep the chloride ion diffusion coefficient below 1.5×10⁻¹²m²/s. A migrating corrosion inhibitor (calcium nitrite-based, dosage 2%-3%) is also added to form a protective film on the steel reinforcement surface, slowing the corrosion process.

Structural design must focus on waterproofing and drainage. Water channels and weep holes are provided at panel joints, designed on the pressure-equalised cavity principle. For the Hainan project, Qinglong Group designed a 5% drainage slope for the GRC panels and installed stainless steel flashing at the joints. The rear ventilated cavity is no less than 30mm wide, ensuring air circulation and timely removal of moisture. This structural design keeps the relative humidity in the cavity behind the panels below 75% year-round.

Surface treatment is the last line of defence. Qinglong Group applies a fluorocarbon coating (dry film thickness ≥30μm) or silane impregnation treatment, raising the surface contact angle above 110° to create a "lotus effect". Regular maintenance is also important; reapplying the protective agent every two years is recommended to ensure long-term moisture protection.