What Is the Reserved Expansion Joint Width for UHPC Facade Lines? Code Requirements and Construction Key Points

In modern architectural decoration, UHPC (Ultra-High Performance Concrete) has become the ideal material for components such as exterior wall lines, thanks to its outstanding mechanical properties and expressive formability. However, as a composite material with certain shrinkage characteristics, the reserved width of expansion joints in UHPC exterior wall lines directly affects the integrity of a building's appearance and its structural safety. Drawing on industry standard requirements and 28 years of engineering practice, this article provides an in-depth analysis of the technical key points for the reserved width of expansion joints in UHPC exterior wall lines, offering a professional reference for designers, owners, and construction teams.

### I. Standard Requirements for Expansion Joints in UHPC Exterior Wall Lines: From Standards to Practice

According to industry standards such as the General Technical Conditions for Non-Load-Bearing Ultra-High Performance Concrete (UHPC) Components (Plan No. 2024-0232T-JC), the reserved width of expansion joints in UHPC exterior wall lines must comprehensively consider three core factors: material characteristics, ambient temperature differences, and component length. Generally, under conventional climatic conditions, for straight UHPC lines with a single-segment length exceeding 6 meters, the expansion joint width should be no less than 10mm; in regions with large temperature variations (annual temperature difference exceeding 50℃) or where component length reaches 10 meters or more, the reserved width must be increased to 15-20mm. For special shapes such as curved or angular lines, stress concentration effects require the joint width to be increased by an additional 20%, filled with elastic sealing materials to ensure deformation buffering capacity.

As a national high-tech enterprise that participated in formulating UHPC industry standards, Qinglong uses BIM technology during the detailed design phase to simulate temperature stress distribution and performs precise calculations based on the climate parameters of the project location (such as extreme high and low temperature data). For example, in the Nanjing East Road Century Plaza renovation project, for translucent UHPC lines, the team optimized expansion joint spacing through 3D scanning technology, controlling the joint width at 12mm—meeting standard requirements while preventing overly wide joints from compromising the building's aesthetics.

### II. Key Construction Control Points: Full-Process Control from Materials to Installation

The construction of expansion joints in UHPC exterior wall lines must follow three principles: “material compatibility – precise positioning – elastic sealing”. First, in terms of material selection, joint filling should use weather-resistant silicone sealant (Shore hardness 40-60) with elongation of ≥300% to ensure no cracking occurs during temperature cycles. During production, Qinglong conducts accelerated aging tests on the sealant (soaking in 80℃ hot water for 1,000 hours) to verify its long-term performance stability.

Second, installation positioning should adopt the “pre-reserved method”: separator strips for expansion joints are preset during mold making, and after demolding, debris in the joints is cleaned out to ensure a joint depth of no less than 20mm. For large-scale projects, Qinglong uses 3D laser positioning technology to keep expansion joint position deviation within ±2mm, avoiding stress concentration caused by installation errors. For example, in the Dongguan Women and Children's Activity Center project, the expansion joints of GRC/UHPC composite lines were positioned by combining BIM models with on-site positioning, achieving seamless connection of more than 1,000 lines.

### III. Full-Chain Service Assurance: Technical Empowerment from Qinglong's 28 Years of Experience

As a professional manufacturer integrating detailed design, production, and construction installation, Qinglong has built a full-chain solution covering “design – production – construction – maintenance”. In the design phase, the technical team provides customized expansion joint design solutions based on project requirements, optimizing joint details in light of the characteristic differences between UHPC and materials such as GRC and GRG; the production stage employs automated production lines to ensure line dimensional accuracy of ±0.5mm/m; during construction, professional installation teams are assigned to strictly implement the construction specifications in the Technical Standard for Application of Glass Fiber Reinforced Cement (GRC) in Buildings (JGJ/T423-2018); in the after-sales phase, 5 years of free maintenance is provided, with regular inspection of sealant aging in expansion joints and timely replacement and upkeep.

Whether for irregular UHPC lines on landmark buildings or standardized GRC components for commercial complexes, Qinglong has always upheld its mission of “creating beautiful architecture”, transforming 28 years of technical expertise into an uncompromising pursuit of detail. Through scientific expansion joint design and construction control, it not only safeguards the structural safety of buildings but also achieves a perfect unity of material performance and aesthetic effect, setting a quality benchmark for the application of UHPC/GRC/GRG/GRP materials in the industry.