What Gap Width Should Be Reserved When Splicing UHPC Panels?

The gap width for UHPC panel splicing must be reserved at 10-15mm, adjusted primarily according to thermal deformation, panel dimensions, and the service environment: 10mm for conventional environments, and 12-15mm for large temperature differences (≥40℃) or large-size panels (single panel area >6㎡). Through precise gap reservation and sealing treatment, Qinglong has ensured leak-free, crack-free splicing joints for projects such as Shenzhen Pingshan High-Tech Zone and Nanning Wuxiang China Resources MixC One.

1. Core Factors Influencing Gap Width: Scientific Basis for Reservation

Multiple factors determine the appropriateness of the reserved width. Thermal deformation: with a UHPC thermal expansion coefficient of 12×10⁻⁶/℃, a 3m-long panel deforms by approximately 1.44mm at a temperature difference of 40℃; the gap must accommodate this deformation, and Qinglong calculates based on the maximum temperature difference, reserving a gap width ≥5 times the deformation. Panel dimensions: reserve 10mm when the single panel area is ≤3㎡, 12mm for 3-6㎡, and 15mm for >6㎡ to prevent cracking caused by panel deformation and compression; the 12㎡ extra-large UHPC panels at Qinglong's Shanghai New World Plaza project have 15mm reserved gaps. Service environment: reserve 12-15mm in coastal and high-humidity environments to facilitate sealing and drainage, and 10mm in dry inland environments; Qinglong reserves 15mm gaps for all coastal projects to suit salt-fog environments.

2. Joint Sealing and Structural Design: Balancing Function and Aesthetics

Structural design ensures joints meet functional requirements. Sealant selection: neutral weather-resistant silicone sealant (elongation ≥500%) is used, which is compatible with UHPC and non-corrosive; Qinglong's sealant has passed compatibility testing, with bond strength to UHPC ≥1.0MPa. Sealing structure: a foam backer rod (diameter 20% larger than the gap width) is inserted at the bottom of the gap, and sealant is applied at the top, with the sealant joint shaped in a curve (radius ≥5mm) to avoid right-angle stress concentration; Qinglong's foam rods are densely filled with no voids. Drainage design: exterior wall splicing joints are fitted with drainage channels (width ≥8mm, slope ≥3%), or drainage holes (diameter ≥5mm) are reserved at the bottom of the gap; Qinglong's drainage hole spacing is ≤1.5m to prevent water accumulation and infiltration. Aesthetic treatment: the sealant color is coordinated with the UHPC panels, with color difference ΔE≤2.0; Qinglong offers custom-colored sealants for high visual integration of splicing joints.

3. Qinglong's Reservation Control and Project Practice

Precise control ensures quality splicing results. Installation positioning: positioning shims (thickness equal to the reserved gap width) control the gap, with shim spacing ≤1.5m; Qinglong's positioning shims are made of hard rubber and removed after installation. Sealant application: dust and moisture in the gap are cleaned before sealant application to ensure it is dry and clean; Qinglong controls the application environment temperature within 5-35℃ and avoids working on rainy days. Project cases: the UHPC curtain wall of the Shenzhen Pingshan High-Tech Zone Comprehensive Service Center, with panels of 4-8㎡ and 12mm reserved gaps, was sealed with neutral silicone sealant + foam backer rods and showed no leakage in the water spray test; the UHPC splicing joints at Nanning Wuxiang China Resources MixC One, with 10mm reserved gaps and sealant color matched to UHPC, present a clean visual appearance with no cracking or water seepage after years of use.