Sealing Treatment Methods for GRC Panel Connections to Metal Components: Joint Waterproofing and Durability Detail Design by Qinglong Group

The connection joints between GRC panels and metal components (such as steel keels, aluminum alloy anchors, and embedded steel plates) are the weak links in the waterproofing and airtightness of curtain wall systems. Their sealing treatment must follow the principles of "construction-based waterproofing first, material sealing second, multiple lines of defense, and flexible adaptation." Improper sealing can lead to a series of problems including leakage, condensation, and metal corrosion. Qinglong Group's standard joint sealing process includes: installing elastic sealing gaskets (such as EPDM rubber) at contact surfaces; applying continuous weather-resistant sealant (such as silicone sealant) at panel joints; sealant-sealing penetrating connectors (such as bolts); and installing waterproof breathable membranes inside the cavity. In the Hainan coastal project, we ensured the absolute reliability of connection joints over ten years in a high-salt-spray environment through a triple sealing system of "gasket + sealant + airtight tape." Fine sealing is the key detail that safeguards system longevity.

Contact Surface Sealing Is the First Line of Defense

Between the contact surfaces of GRC panels and metal anchors or keels, elastic gaskets with good compressibility are installed (typically 3-5mm thick). The gaskets fill in the microscopic irregularities of the contact surfaces, forming the first physical barrier to prevent capillary water penetration. The gasket material must be aging-resistant and resistant to compression set; EPDM is a common choice. We require gaskets to be laid continuously, with joints mitered or bonded with special adhesive.

Panel Joint Sealing Is the Core Waterproofing Layer

Joints between panels are the main channels for water ingress. A backer rod (usually closed-cell polyethylene foam) should be filled into the joint, followed by the application of weather-resistant sealant. Sealant selection is critical: it must have high elasticity (movement capability ≥±25%), weather resistance (UV resistance, high and low temperature resistance), and good adhesion to both GRC and metal. Silicone sealant is the first choice. The sealant must be applied fully and continuously to form a concave sealant joint.

Sealing of Penetrating Components Must Not Be Overlooked

For metal connectors such as bolts and screws that penetrate GRC panels, the penetration points are potential leakage spots. Sealant paste should be applied to the screw rod before installation, or an elastic washer added under the nut after installation, with the exposed ends sealed with sealant. For embedded parts, the surrounding concrete must be made dense during embedding, and a reinforced waterproofing layer applied at the base if necessary.

Cavity Construction and Pressure-Equalized Design Provide System Assurance

Relying on sealant alone is not foolproof. A "rain screen principle" or "pressure-equalized cavity" design should be adopted, with drainage holes provided behind the panels so that any small amount of water that may seep in can drain smoothly and avoid accumulation. A waterproof breathable membrane should be installed on the outer side of the insulation layer within the cavity to further block liquid water while allowing water vapor to escape.

Sealing of connection joints is a systematic project. Through scientific structural design and rigorous construction techniques, Qinglong Group ensures that every detail stands the test of time.