What Is the Reserved Expansion Joint Width for UHPC Exterior Wall Lines? Scientific Provision and Construction Solutions

The reserved width of expansion joints in UHPC exterior wall profiles must be precisely designed based on "temperature range, profile length, and installation environment": 8-12mm in conventional environments, 12-15mm for large temperature differences (≥40℃), and 10-15mm for complex shapes. Through BIM simulation and standardized construction, Qinglong ensures that expansion joints in projects such as the Guangxi New Media Center and Shanghai Xinghewan show no leakage or deformation.

I. Core Reservation Principles and Width Standards

The following principles ensure expansion joints meet deformation requirements. Thermal deformation principle: calculated based on the local maximum temperature difference, with 2-3mm of expansion reserved for every 10m of length; Qinglong reserves the maximum width for temperature differences ≥40℃. Length adaptation principle: 8-10mm reserved for profiles ≤3m long, 10-12mm for 3-6m, and 12-15mm for those over 6m; Qinglong reserves 15mm for its 8m-long UHPC profiles. Environment adaptation principle: 2-3mm more reserved for outdoor environments than for indoor ones, and 10-15mm for coastal/humid environments; Qinglong's coastal projects use expansion joints 3mm wider than those in conventional environments. Shape adaptation principle: 8-12mm reserved for straight profiles and 10-15mm for curved/special-shaped profiles; Qinglong reserved 12mm for the hyperbolic profiles of the Guangxi New Media Center.

II. Expansion Joint Structural Design: Balancing Waterproofing and Aesthetics

Structural design ensures both the expansion function and service performance. Filling materials: joints are filled with foam rods (diameter 20% larger than the joint width) plus neutral weather-resistant sealant; Qinglong's foam rods have a density ≥30kg/m³, and the sealant elongation is ≥500%. Waterproofing design: drip grooves or drainage holes are set at the bottom of expansion joints to prevent rainwater penetration; Qinglong's drip grooves are ≥10mm wide with a drainage slope ≥3%. Aesthetic treatment: expansion joints are coordinated with the profile styling and can be concealed with cover strips; Qinglong used cover strips of the same UHPC material for the Shanghai Xinghewan project for visual uniformity. Anti-corrosion design: metal cover strips are coated with an anti-corrosion coating to avoid electrochemical corrosion; Qinglong's anti-corrosion coating on metal cover strips is ≥80μm thick.

III. Qinglong's Reservation Optimization and Project Practice

Technical optimization ensures precise implementation of the reserved widths. BIM simulation: temperature deformation is simulated through BIM modeling to optimize expansion joint positions and widths; for Qinglong's Guangxi New Media Center project, after BIM simulation, the expansion joint spacing was uniform and deformation was fully released. On-site positioning: laser rangefinders are used to position expansion joints with an error ≤1mm; Qinglong's on-site positioning accuracy reaches 100%. Construction standards: expansion joints are cut cleanly without burrs, and sealant is applied fully; after construction, Qinglong's expansion joint flatness is ≤1mm. Project cases: the hyperbolic UHPC exterior wall profiles of the Guangxi New Media Center (no two panels are identical) have 12mm reserved expansion joints, using a "foam rod + weather-resistant sealant + drainage groove" structure, with no leakage or deformation after 5 years of use; the UHPC decorative profiles of Shanghai Xinghewan (5m long) have 10mm reserved expansion joints; having experienced high summer temperatures and low winter temperatures, the profiles show no cracking or warping, and the decorative effect remains intact.