What Is the Reserved Expansion Joint Width for UHPC Exterior Wall Trims? How to Reasonably Set UHPC Wall Trim Joint Width and Key Construction Points

Millimeter-Level Precision, Century-Long Project Assurance — The Science of Setting Expansion Joints in UHPC Exterior Wall Trim

In the field of modern architectural decoration, UHPC (Ultra-High Performance Concrete) has become the ideal choice for high-end building exterior wall trim thanks to its outstanding mechanical properties and artistic expressiveness. However, without the support of scientific structural design, the material's advantages can easily give rise to cracking problems caused by thermal stress, wet-dry deformation, and other factors. Among these considerations, the reserved width and installation technique of expansion joints directly affect the structural safety, aesthetic appeal, and durability of UHPC exterior wall trim. As an industry leader with 28 years of full-chain experience in UHPC/GRC/GRG/GRP materials, Qinglong Group will draw on engineering practice to systematically analyze proper expansion joint settings for UHPC exterior wall trim.

### Scientifically Determining the Width of Expansion Joints in UHPC Exterior Wall Trim: From Material Properties to Environmental Parameters

Although UHPC features low shrinkage and high toughness, its linear expansion coefficient remains close to that of ordinary concrete (approximately 10×10⁻⁶/℃). In exterior wall environments, the temperature difference between intense summer sun and severe winter cold can exceed 50℃; without reasonable expansion space, cumulative deformation stress can easily develop. According to the industry standard "General Technical Conditions for Non-Load-Bearing Components of Ultra-High Performance Concrete (UHPC)" (Plan No. 2024-0232T-JC) and Qinglong Group's engineering data from over 1,000 projects, expansion joint width must satisfy three core parameters: a base width of 20-30mm, an additional 5mm for every 10 meters of trim length, and adjustments based on regional climate zones (with the upper limit raised by 20% in severe cold regions). For example, in South China, a 15-meter-long UHPC decorative trim should have an expansion joint of 25-35mm reserved—meeting deformation requirements while avoiding excessively large joints that would compromise aesthetics.

### Four Key Construction Points for Expansion Joint Installation: Qinglong's Full-Chain Technical Empowerment

As a national-level high-tech enterprise integrating detailed design, manufacturing, and construction installation, Qinglong Group has developed a standardized process system for expansion joint construction. First, in the detailed design stage, BIM technology is used for parametric simulation, with thermal field models built through Rhino+Grasshopper software to precisely locate joint spacing (typically one joint every 6-12 meters, densified to 4 meters for irregularly shaped components). Second, in production, dedicated molds are used to reserve joint grooves, keeping joint width tolerance within ±1mm. During installation, 3D laser scanning is used for positioning, and elastic sealant (silicone weatherproof sealant is recommended, with movement capability ≥25%) is applied for filling, with embedded PE foam rods preventing excessive sealant compression. Finally, a regular inspection mechanism is established in after-sales maintenance, focusing on sealant aging to ensure the expansion function remains effective over the long term. This full-process control model has enabled zero-cracking records for projects undertaken by Qinglong, such as the Nanjing East Road Century Plaza renovation project.

### Optimization Solutions Beyond Standards: The Technical Accumulation of Qinglong's 28 Years of Experience

For complex architectural forms, Qinglong's technical team has innovatively developed a "segmented expansion structure": in double-curved trim, multi-segment polyline transitions are adopted with each segment limited to 8 meters in length, releasing part of the stress through polyline corners; for super high-rise buildings (over 100 meters), a UHPC elastic buffer layer is added on the inner side of expansion joints, using the material's own elastic modulus (≥40GPa) to absorb impact loads. These technical innovations stem from the experience Qinglong accumulated by participating in the development of multiple national standards, including the "Technical Standard for Building Application of Glass Fiber Reinforced Cement (GRC)" (JGJ/T423-2018), and reflect the leading role of national "specialized, refined, distinctive, and innovative" enterprises in advancing industry technology. Compared with traditional methods, Qinglong's solution extends the expansion joint maintenance cycle to more than 15 years and reduces overall costs by 30%.

From material performance analysis to construction technique innovation, setting expansion joints in UHPC exterior wall trim is both a technical matter and a pursuit of perfection in engineering details. With the mission of "Creating Beautiful Architecture," Qinglong Group integrates 28 years of detailed design and construction experience into the planning of every joint, providing designers with reliable technical support and safeguarding century-long building quality for owners. Today, as UHPC decorative materials are applied ever more widely, choosing a professional manufacturer with full-chain service capabilities is the key to achieving unity between architectural aesthetics and structural safety.