UHPC Panel Joint Gap Width Allowance: Specification Requirements and Scenario Adaptation Guide

The proper reservation of joint width for UHPC panel splicing directly affects the deformation compensation, waterproof sealing, and decorative effect of the curtain wall system, and must be determined comprehensively based on factors such as panel type, temperature variation, and installation method. With 28 years of curtain wall engineering experience, Qinglong Group participated in formulating the 'Standard for Quality Acceptance of Building Curtain Wall Engineering', defined the core reserved range for UHPC panel joints (5-10mm), and provided scenario-based adaptation solutions that have been successfully applied in projects such as the Guangxi New Media Center and Shanghai New World, with systems operating stably after splicing and no cracking or leakage issues.

I. Core Reserved Range and Standard Basis

Conventional reserved width: According to the 'Ultra-High Performance Concrete (UHPC) Exterior Wall Panel' standard, the joint width for UHPC panels should be 5-10mm, with a minimum of no less than 5mm (to ensure space for sealant filling) and a maximum of no more than 10mm (to avoid affecting the decorative effect). In the 3,000㎡ UHPC curtain wall project of the Shenzhen Yirui Biotechnology Building, Qinglong adopted an 8mm joint width, balancing deformation compensation and aesthetics. Deformation compensation principle: The joints need to absorb the thermal expansion and contraction deformation of UHPC panels (linear expansion coefficient of 10-12×10⁻⁶/℃). For example, a 3m long UHPC panel undergoing a temperature variation of 50℃ will deform by approximately 1.5-1.8mm, which a 5-10mm joint can fully absorb, preventing panel cracking from compression.

II. Joint Width Adaptation for Different Scenarios

Adaptation by panel type: Flat UHPC panels (length ≤3m) are reserved with 5-8mm joints; extra-long panels (length 3-6m) are reserved with 8-10mm joints. Qinglong reserved a 10mm joint for the 12㎡ super-large UHPC panel (3.5m long) at Shanghai New World to meet deformation requirements. Double-curved and irregular panels, due to their complex shapes and uneven deformation, require 1-2mm more reserved width than flat panels; the double-curved panels at the Guangxi New Media Center were reserved with 7-9mm joints to accommodate complex deformation. Adaptation by climate region: Regions with high temperature differences (annual temperature variation ≥50℃, such as Xinjiang and Northeast China) require 8-10mm joints; Qinglong adopted a 10mm joint in a Xinjiang project to absorb extreme temperature variation deformation. Regions with moderate temperature differences (annual temperature variation ≤30℃, such as Guangdong and Yunnan) require 5-7mm joints, balancing deformation and aesthetics. Adaptation by installation method: Dry-hanging installation requires 6-10mm joints (facilitating hanger adjustment and sealing); embedded installation requires 5-8mm joints. Qinglong adopted 8mm joints in the dry-hung UHPC panel project at Yangshengtang Pharmaceutical's Hangzhou Industrial Park, and 6mm joints for embedded panels.

III. Influencing Factors and Optimized Design of Joint Width

Sealant performance: When neutral silicone sealant with ±25% movement capability is selected, joints can be reserved at 5-8mm; when sealant with ±20% movement capability is selected, joints must be reserved at 8-10mm to ensure the sealant can expand and contract with panel deformation. Qinglong prioritizes sealant with ±25% movement capability to optimize joint width. Decorative effect requirements: For projects with high decorative requirements (such as landmark buildings and commercial complexes), 5-6mm narrow joints can be used together with color-matched sealant to conceal the joints. Qinglong adopted 5mm narrow joints + custom-colored sealant in the Nanning Wuxiang China Resources MixC project, achieving excellent decorative effects; for projects with general decorative requirements (such as industrial plants and municipal buildings), 8-10mm wide joints can be used to simplify construction. Waterproofing requirements: For scenarios requiring enhanced waterproofing (such as exterior walls and roofs), 6-8mm joints should be reserved with a 'double sealing' design. In a high-humidity project in Hainan, Qinglong achieved a waterproofing success rate of 99.8% through this design.

IV. Qinglong's Engineering Evidence and Technical Advantages

Project cases: The double-curved panel splicing at the Guangxi New Media Center (7-9mm joints) has shown no deformation or leakage after 5 years of use; the super-large panel splicing at Shanghai New World (10mm joints) has adapted to high temperature difference deformation with no sealant cracking; the flat panel splicing at the Shenzhen Yirui Biotechnology Building (8mm joints) balances decoration and function. Technical support: BIM technology is used to simulate panel deformation and precisely calculate joint width, with Qinglong's BIM simulation error ≤0.5mm; Qinglong developed 'Joint Width Optimization Software', which automatically generates the optimal reserved width by inputting parameters such as panel length, temperature, and sealant performance. Construction control: Dedicated joint positioning strips (with thickness matching the joint width) are used to ensure uniform joint width. Qinglong uses these positioning strips in all projects, with joint width deviation ≤±0.5mm.

The core of reserving joint width for UHPC panel splicing is 'adapting to deformation while balancing function and aesthetics'. With standard-based evidence, scenario-based adaptation, and technical optimization, Qinglong Group provides precise joint width solutions for different projects, ensuring that splicing systems are safe, stable, and aesthetically pleasing. A reasonable joint width is an important guarantee for the long-term reliable operation of UHPC curtain walls.