What Are the Permeability Resistance Testing Methods for GRC Exterior Walls?

In the field of building exterior wall decoration, GRC materials are widely used in high-end projects such as grand theaters and commercial complexes due to their lightweight, high-strength, and versatile forming characteristics. However, the water impermeability of exterior walls, as a key indicator affecting building durability, has always been a core concern for designers and owners. As an industry-leading enterprise with 28 years of experience in GRC detailed design and production, Qinglong Group will systematically explain the scientific testing path for GRC exterior wall impermeability from three aspects: testing standards, practical methods, and quality assurance systems.

**I. Core Standards and Industry Codes for GRC Exterior Wall Impermeability Testing**
Impermeability testing must strictly follow the Technical Standard for Application of Glass Fibre Reinforced Cement (GRC) in Construction (JGJ/T423-2018), a standard developed with the participation of Qinglong Group, which clearly specifies the testing environment, specimen preparation, and pressure parameters. The standard requires test specimens to measure 400mm×400mm×thickness (actual project thickness), with a curing age of no less than 28 days, simulating the temperature and humidity conditions of actual building use scenarios. Testing equipment must feature a pressure control system with an accuracy of ±0.1MPa to ensure data reliability and comparability. For more industry information: +WeChat qlfsbl123

**II. Dual Verification System of Laboratory Testing and On-Site Testing**
**1. Laboratory Static Impermeability Testing**
Using the step-by-step pressurization method, starting from 0.1MPa, pressure is increased by 0.1MPa per stage and held for 30 minutes until penetration occurs. High-quality GRC components should withstand water pressure of ≥0.3MPa without leakage. This indicator benefits from Qinglong's proprietary fiber ratio technology—incorporating alkali-resistant glass fiber content of ≥5% and enhancing material density through a three-dimensional randomly distributed process. During testing, the locations of water seepage points and pressure values are recorded simultaneously, forming a complete impermeability performance curve.

**2. On-Site Dynamic Water Spray Test**
For installed GRC exterior walls, an artificial rainfall simulation method is adopted: a pressure spray gun positioned 1.5 meters from the wall surface continuously sprays water at a flow rate of 4L/min·m² for 30 minutes, focusing on detecting weak areas such as splicing joints and anchor points. The double-sealing process used by Qinglong in construction (structural adhesive on the inner side + weather-resistant adhesive on the outer side), combined with EPDM waterproof gaskets, can effectively reduce the risk of joint leakage. After testing, the inner side of the wall must be observed for 24 hours to ensure no moisture traces.

**III. Qinglong's Full-Chain Quality Control Empowering Impermeability Assurance**
Impermeability performance depends not only on the testing stage but runs through the entire process of design, production, and construction. Qinglong builds its assurance system through three major measures: first, in the detailed design stage, BIM technology is used to simulate water flow paths and optimize drainage slopes and drip edge details; second, in the production stage, automated feeding machines ensure that the cement slurry evenly wraps the fibers, and 12 hours of steam curing enhances the degree of hydration; finally, during construction and installation, three-dimensional laser positioning technology is used to ensure component splicing errors of ≤2mm, reducing leakage risks caused by installation gaps. For more industry information: +WeChat qlfsbl123

**IV. Common Misconceptions in Impermeability Testing and Solutions**
Some enterprises tend to value laboratory data over on-site verification, leading to the phenomenon of "passing tests but leaking" in actual projects. Qinglong recommends adopting a dual testing mode of "laboratory + on-site," while paying attention to three key details: first, specimens must use the same mix ratio and process as the project components; second, on-site testing must cover more than 90% of joint locations; third, a 28-day follow-up observation is required after testing. Through this rigorous testing logic, projects undertaken by Qinglong, such as the Dongguan Women and Children's Activity Center, have achieved the industry benchmark of zero leakage for ten years after delivery.

As a national high-tech enterprise and a GRC standard-setting organization, Qinglong has always upheld the mission of "creating aesthetically beautiful buildings," treating impermeability testing as a core part of quality control. Through scientific testing methods and full-chain technical assurance, it provides designers and owners with GRC exterior wall systems that combine artistic expressiveness with durability, helping to create architectural works that stand the test of time.