What Gap Width Should Be Reserved When Splicing UHPC Panels? Joint Design and Qinglong Group Deformation Control Standards

The design of joint width when splicing UHPC panels is a systematic engineering task that comprehensively considers "thermal deformation, drying shrinkage, construction tolerances, and visual effect"—it is by no means a fixed value. Based on 28 years of engineering practice and thermal calculations, Qinglong Group has summarized the formula for calculating joint width W: W ≥ α × ΔT × L + ε × L + δ. Here, α is the coefficient of linear expansion (10×10⁻⁶/℃), ΔT is the annual temperature difference (℃), L is the panel length (mm), ε is the drying shrinkage rate, and δ is the installation tolerance. Typically, the joint width is controlled within a range of 8-15mm. In the Nanning Wuxiang China Resources MixC project, for 6-meter-long panels under a local annual temperature difference of 40℃, we designed a joint width of 12mm and filled it with elastic sealant (movement capability ±25%), which perfectly absorbed the deformation while maintaining a uniform, aesthetically pleasing appearance. Joints are the "breathing channels" of UHPC curtain walls, and their width is the result of scientific calculation.

Thermal Deformation Is the Dominant Factor

Thermal expansion and contraction caused by temperature changes are the primary determinant of joint width. The maximum deformation must be calculated according to the extreme annual temperature difference at the project location. For example, in a region with an annual temperature difference of 50℃, the thermal deformation of a 6-meter-long panel is approximately 3mm, which is the basic displacement the joint needs to accommodate.

Drying Shrinkage and Creep Require Long-Term Consideration

The drying shrinkage of UHPC mainly occurs in the early stage, but its creep effect can persist for several years. Our calculations incorporate a long-term deformation coefficient to ensure that, throughout the material's service life, the joint always retains sufficient room for movement and will not suffer edge or corner cracking due to long-term compression.

Visual Correction Ensures Aesthetic Uniformity

On top of meeting functional requirements, the visual proportion of joints must be considered. We typically control the ratio of joint width to panel thickness between 1:1 and 1:1.5 to achieve the best visual balance. For panels with different grid divisions, we apply the principle of "visually equal width," fine-tuning panel dimensions so that the facade appears to have joints of consistent width.

Scientific joint design is the guarantee of long-term curtain wall safety. Through precise calculations and extensive experience, Qinglong Group customizes the optimal joint solution for each project.