What Type of Sealant Is Used for the Joint Treatment of UHPC Curtain Wall Panels?

The joint treatment of UHPC curtain wall panels is a critical link in ensuring a building's waterproofing performance and aesthetic appeal, and the choice of sealant directly determines the long-term durability of the curtain wall system. Based on 28 years of engineering practice, Qinglong Group has distilled the technical requirements for UHPC-specific sealants into four core indicators: “high elastic modulus, excellent weather resistance, good adhesion, and moderate movement capability.” In the Century Plaza project on Nanjing East Road, Shanghai New World, we selected a single-component modified silicone sealant and successfully met the thermal deformation challenge of super-large panels. The right sealant choice is the “flexible line of defense” of a curtain wall system.

Modified silicone sealant (MS) is currently the preferred material for UHPC curtain wall joints, with an elastic recovery rate of over 80%, capable of effectively accommodating joint width variations of more than ±25%. For the Shenzhen Yirui Biotechnology Building project, Qinglong specially selected a two-component silicone sealant with superior adhesion for the heterogeneous material joints between UHPC panels and the glass curtain wall. It should be noted that the sealant's modulus should match the elastic modulus of the UHPC: too high a modulus will cause interfacial stress concentration, while too low a modulus may compromise the sealing effect.

Weather resistance is a key evaluation criterion for sealants; quality sealants should withstand temperature variations from -40°C to 90°C, with a performance degradation rate of no more than 15% under UV exposure. Qinglong requires all sealants to pass a 1000-hour accelerated aging test to ensure that no chalking or cracking occurs within the project's design service life. In Hainan's high-temperature, high-humidity environment, we pay particular attention to the mildew resistance of the sealant and select specialized formulations containing mildew inhibitors.

Application workmanship directly affects the sealing performance of the sealant. Qinglong has established strict application procedures: joint cleanliness must meet the Sa2.5 standard, closed-cell polyethylene foam rods are used as backing material, sealant thickness should be 0.5-0.7 times the joint width, with a minimum thickness of no less than 6mm. In the complex curved joint treatment for the Wuhan Han Show Theater, we used specialized application tools to ensure the sealant joints are full, continuous, and aesthetically pleasing.

Qinglong Group recommends establishing a regular inspection and maintenance system for sealants, with a comprehensive inspection every 5 years and timely replacement before the sealant reaches its design service life. Only through scientific selection and meticulous application can the sealant truly serve as a reliable safeguard for the UHPC curtain wall system.