UHPC Exterior Wall Molding Expansion Joint Reserved Width Specifications and Construction Key Points Explained

The temperature joint of a building is the intelligent language of dialogue between architecture and its environment, and, more importantly, a delicate balance between material performance and engineering artistry. As an industry leader with 28 years of deep expertise in the UHPC/GRC/GRG/GRP field, Qinglong Group will, from the dual perspectives of standard interpretation and construction practice, analyze the technical code behind the reserved width of expansion joints in UHPC exterior wall mouldings, helping designers and project managers achieve a perfect unity of architectural aesthetics and structural safety.

### The Regulatory Foundation for the Reserved Width of Expansion Joints in UHPC Exterior Wall Mouldings

UHPC (Ultra-High Performance Concrete), with its outstanding mechanical properties and durability, has become an ideal choice for modern building envelopes, yet the material's thermal expansion and contraction still need to be addressed scientifically. Under the industry standard framework of the "General Technical Conditions for Non-Load-Bearing Components of Ultra-High Performance Concrete (UHPC)" (Plan No. 2024-0232T-JC), and drawing on Qinglong Group's experience of participating in drafting technical specifications, the reserved width of expansion joints must comprehensively consider three core factors: the ambient temperature difference range, component length, and installation method. In most climate zones of China, UHPC mouldings with a single-direction length exceeding 6 meters should have an expansion joint width of 15-25mm reserved; in regions with drastic temperature differences (such as Northeast and Northwest China), it is recommended to increase this to 20-30mm, with the joint width deviation controlled within ±2mm, ensuring sufficient deformation space without compromising the decorative effect.

### Four Key Points for UHPC Expansion Joint Construction

**1. Precise Positioning and Chalk-Line Marking** Before construction, BIM technology must be used for in-depth design, with 3D scanning employed to locate the component installation axes, ensuring that expansion joint positions are aesthetically consistent with the building facade grid. In the Century Plaza renovation project on Nanjing East Road, Qinglong Group coordinated the expansion joints of light-transmitting UHPC components with the lighting system through parametric design, achieving a fusion of function and art. When snapping lines, a laser line projector must be used to ensure that the straightness deviation of the joint is ≤3mm/2m, laying a precision foundation for subsequent construction.

**2. Scientific Selection of Joint Filling Materials** Expansion joint filling must balance elastic recovery and weather resistance. EPDM rubber strips (Shore hardness 60±5) or polyurethane elastic sealant are recommended, with elongation of ≥300% and good bonding compatibility with the UHPC substrate. Qinglong's production base is equipped with a professional testing laboratory capable of conducting hot-cold cycling tests on filling materials from -40℃ to 80℃, ensuring that sealing performance is maintained even under extreme climates.

**3. Crack-Resistant Construction and Installation Details** At the ends of the UHPC components on both sides of the expansion joint, a 50mm-wide reinforced area should be provided, using 8mm-diameter stainless steel fiber mesh sheets to enhance crack resistance. During installation, slidable connectors should be used to allow components to displace horizontally and avoid stress concentration. In the Dongguan Women and Children's Activity Center project, Qinglong innovatively applied a "flexible anchoring system," enabling the expansion joint deformation of the GRC/UHPC composite mouldings to reach 120% of the design value, effectively solving the cracking problem of traditional rigid connections.

**4. Finished Product Protection and Quality Acceptance** After construction is completed, PE protective film must be applied immediately over the joints to prevent mortar contamination. During acceptance, focus on checking joint width uniformity, filling material fullness, and connector flexibility, and, with reference to Qinglong's enterprise standard Q/QL 003-2023 "Specification for Construction Quality Acceptance of UHPC Decorative Components," ensure that every expansion joint meets the three-dimensional standard of "free deformation, reliable sealing, and flat appearance."

From material R&D to project implementation, Qinglong Group has always taken "creating beautiful architecture" as its mission, transforming 28 years of full-chain experience into systematic solutions for industry pain points. Whether it is the expansion joint treatment of UHPC exterior wall mouldings or the in-depth design of complex GRC/GRG/GRP shapes, Qinglong is committed to providing designers with professional support that combines technical feasibility and artistic expressiveness, making every architectural detail a dual testament to quality and aesthetics. Choosing Qinglong means choosing not only a material supplier, but also a trustworthy partner for architectural decoration system solutions.