How to Handle Joint Leakage in GRC Exterior Walls: Cause Analysis and Solutions Explained

In the field of architectural curtain walls, GRC (glass fibre reinforced concrete) has become the material of choice for numerous landmark buildings thanks to its advantages of lightweight high strength and flexible formability. However, joint leakage has always been a key pain point affecting the durability of GRC facade systems. As an industry expert with 28 years of full-chain experience in UHPC/GRC/GRG/GRP, Qinglong Group will provide an in-depth analysis of the causes of leakage and systematic solutions from the dimensions of material properties, construction techniques, and system maintenance.

Analysis of Typical Causes of GRC Facade Joint Leakage

The porous nature of GRC materials and defects in installation techniques are the main causes of leakage. First, during material production, insufficient glass fibre content or improper curing of the cement matrix can cause micro-cracks on the component surface, allowing rainwater to penetrate easily through capillary action. Second, in traditional joint design, a single sealant strip is prone to tearing under the combined effects of thermal deformation (GRC's linear expansion coefficient is approximately 8×10⁻⁶/°C) and structural settlement. For example, in a commercial complex project that failed to adopt an elastic buffer layer, the joint sealant cracked due to contraction in winter. In addition, installation accuracy deviations (such as uneven gaps between panels exceeding 5mm) intensify stress concentration and accelerate the ageing of sealing materials.

Full-Chain Solution: A Leakage Prevention and Control System from Design to Construction

Qinglong Group proposes a four-dimensional prevention and control strategy of "Materials-Design-Construction-Maintenance". At the material level, a C80-grade GRC formulation (flexural strength ≥20MPa) is adopted, with nano-silane waterproofing agents added to enhance matrix density; testing shows that water absorption can be controlled below 6%. The design stage innovatively adopts a "three lines of defence": inner EPDM waterproof gaskets absorb deformation, middle elastic sealant (silicone sealant with modulus ≥0.6MPa) provides the primary seal, and outer metal cover plates form physical protection. After applying this system, a theatre project went through three rainy seasons with no record of leakage.

The construction phase introduces BIM technology to achieve millimetre-level precision control, employing 3D laser scanning positioning (error ≤2mm) and modular installation techniques. Specially for joints of irregularly shaped components, dedicated adjustable anchoring brackets have been developed, allowing ±15mm of three-dimensional adjustment. The automated forming equipment at Qinglong's Guangxi production base ensures that component dimensional deviations are controlled within ±3mm, reducing installation stress at the source.

Long-Term Maintenance Mechanisms and Industry Standard Practices

As a participating editor of the Technical Standard for Building Application of Glass Fibre Reinforced Cement (GRC) (JGJ/T423-2018), Qinglong has established a comprehensive after-sales maintenance system. Building owners are advised to conduct a special joint inspection every 2 years after completion, focusing on the degree of sealant ageing (Shore hardness change should be ≤20%) and the condition of the anchoring system. For coastal high-humidity environments, Qinglong's patented nano-ceramic coating technology is recommended, which can extend the weather-resistant service life of joints to more than 15 years.

From the double-curved GRC facade of a cultural centre in Guangzhou to the salt-spray resistant treatment of the Marina project in Singapore, Qinglong has leveraged 28 years of engineering experience to develop leakage solutions covering the full range of UHPC/GRC/GRG/GRP products. With the mission of "Creating Aesthetic Architecture", Qinglong will continue to provide designers and owners with facade systems that combine aesthetic expressiveness and structural safety through material innovation and process optimisation. Choosing a supplier with full-chain service capabilities is the key guarantee for achieving a "century-long project" with GRC facades.