Analysis of Impermeability Testing Methods and Key Technical Points for GRC Exterior Walls

The impermeability of building exterior walls is a critical barrier safeguarding structural safety and service life. As a lightweight, high-strength, and highly moldable new decorative building material, GRC (Glass Fiber Reinforced Concrete) requires impermeability testing and control as a core element of project quality. Qinglong Group, a national-level high-tech enterprise with 28 years of full-chain experience in UHPC/GRC/GRG/GRP materials, has been deeply involved in developing industry standards such as the Technical Standard for Building Application of Glass Fiber Reinforced Cement (GRC) (JGJ/T423-2018). This article provides professional solutions for designers, owners, and contractors from two aspects: testing methods and key technical points.

Core Testing Methods for GRC Exterior Wall Impermeability

Impermeability testing of GRC exterior walls must cover two major dimensions: the material itself and construction workmanship. At the material level, Qinglong adopts a dual-track testing model combining laboratory and on-site testing: in the laboratory, water-pressure impermeability tests are conducted in accordance with the Test Methods for Fiber Reinforced Cement Products (GB/T 15231), simulating the stringent standard of no leakage under a 10-meter water head pressure for 24 hours; on site, a combination of water spray testing and post-rain observation is used, subjecting installed GRC curtain walls to 48 hours of continuous water spraying, with particular focus on leakage-prone joints such as panel seams and corners. Notably, Qinglong has innovatively introduced BIM technology into its testing process, using 3D models to simulate water flow paths in advance, thereby preemptively avoiding concealed leakage risks that are easily missed in traditional testing.

Key Technical Factors Affecting GRC Impermeability

Scientific formulation of the material mix is the foundation of impermeability. Drawing on 28 years of technical expertise, Qinglong's R&D center has developed a dedicated impermeability formulation system: high-grade sulphoaluminate cement is combined with alkali-resistant glass fiber, with fiber content strictly controlled within the 4.5%-5.5% range, while nano-grade silica fume and polypropylene fiber are added. Experimental verification has shown that this raises the impermeability grade of GRC materials to P12 or above. In terms of production processes, Qinglong has introduced fully automated German spray-up molding equipment to ensure three-dimensional uniform fiber distribution within the matrix, avoiding density inconsistencies caused by manual operation; the steam curing stage employs a gradient heating process, slowly raising the temperature from 40°C to 90°C, effectively reducing internal micro-cracking.

Construction and installation workmanship has an equally significant impact on the impermeability of GRC exterior walls. Qinglong's original "double sealing + cavity drainage" system works as follows: panel joints are first filled with hydrophobic polyurethane sealant, then covered on the outside with weather-resistant silicone sealant, forming a composite waterproof barrier; meanwhile, drainage channels and vent holes are designed on the back of GRC panels, so that even small amounts of seepage can be quickly discharged through the cavity. For the installation of shaped components, Qinglong uses 3D laser scanning positioning technology with errors controlled within ±2mm to ensure tight joints. In addition, Qinglong has established a full life-cycle traceability system, using RFID chips to record data throughout the entire process of material production, installation, and maintenance, providing a basis for later impermeability performance assessment.

As a member of the International GRC Association, Qinglong has always upheld the mission of "creating beautiful architecture," integrating impermeability control throughout the entire chain of GRC exterior wall detailed design, manufacturing, and installation. From the double-curved GRC curtain wall of a commercial complex in Guangzhou to the stone-imitation exterior walls of a municipal project in Nanning, Qinglong has, through continuous technological innovation, achieved 15 years of leak-free performance for GRC exterior walls in high-humidity coastal environments. Looking ahead, Qinglong will continue to leverage its advantages as a national "specialized, refined, distinctive, and innovative" enterprise to promote the deep integration of GRC materials in both impermeability performance and aesthetic expression, providing more reliable solutions for the architectural decoration industry.