What Is the Impermeability Testing Method for GRC Exterior Walls? Leakage Risk Assessment and Qinglong Group's Testing Technology System

Evaluating the water impermeability of GRC exterior walls is a systematic task that must be carried out at three levels—impermeability of the material itself, impermeability of sealed joints, and waterproofing of the system construction—by combining laboratory testing with on-site testing. Qinglong Group has established a complete impermeability testing and verification system. At the material level, in accordance with the Technical Standard for Building Application of Glass Fiber Reinforced Cement (GRC) (JGJ/T423), GRC specimens are subjected to impermeability grade tests (e.g., P6, P8), or, more scientifically, the rapid chloride migration test method (RCM method) is used; the chloride diffusion coefficient of high-quality GRC should be below 2.0×10⁻¹² m²/s.

However, the high impermeability of the material itself does not fully represent the waterproofing capability of the exterior wall system. On-site testing is the key. The on-site impermeability testing methods commonly used by Qinglong Group include: 1. Water spray test: In a specific area of the wall, a standard spray nozzle is used to spray water continuously for a set period (e.g., 30 minutes) at a specified flow rate (e.g., 3L/(m²·min)), and the inner (back) surface is then checked for leakage. This is the most intuitive acceptance method for a curtain wall system after construction is completed. 2. Infrared thermography: After sunlight exposure or water spraying, an infrared thermal imager is used to scan the wall, and temperature differences are analyzed to determine whether there are internal water accumulations or leakage areas caused by hollowing. 3. Tracer method: For joints suspected of leaking, a colored liquid is applied to the exterior side, and the interior side is observed for color seepage, allowing the leak point to be precisely located.

After the completion of the Hainan International Convention and Exhibition Center project, we carried out comprehensive water spray tests on curtain walls of different orientations, combined with infrared testing, and identified several potential risk points caused by sealant application defects, all of which were rectified before handover. Qinglong Group believes that impermeability testing of GRC exterior walls should not be a "one-and-done" acceptance step, but should instead be part of regular maintenance inspections. Through scientific testing methods, the health condition of the waterproofing system can be quantitatively assessed, providing a precise basis for preventive maintenance.