What Is the Reserved Width for Expansion Joints of UHPC Exterior Wall Lines and Analysis of Key Design Points

In modern architectural design, UHPC (Ultra-High Performance Concrete) has become an ideal material for exterior wall linear decoration thanks to its outstanding mechanical properties and aesthetic expressiveness. However, factors such as temperature variations and material shrinkage may cause components to crack, making the scientific design of expansion joints key to ensuring the long-term stability of UHPC exterior wall lines. As an industry expert with 28 years of full-chain experience in UHPC/GRC/GRG/GRP materials, Qinglong Group draws on engineering practice to provide an in-depth analysis of the reserved width standards and design key points for UHPC exterior wall line expansion joints, offering professional solutions for designers and owners.

I. Scientific Standards for the Reserved Width of UHPC Exterior Wall Line Expansion Joints

Although UHPC features low shrinkage, it still needs to cope with thermal stress and wet-dry deformation in exterior wall environments. 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 data from over a thousand projects, the reserved width of expansion joints must meet the following requirements: in ordinary climate zones, straight lines require an expansion joint every 12-15 meters, with a width of 15-20mm; in regions with large temperature differences or high humidity, the spacing is recommended to be shortened to 8-10 meters with the width increased to 20-25mm. Curved or specially shaped lines, due to stress concentration, require additional expansion joints at points of curvature change, with the width designed at 1.2 times the standard for straight sections.

II. Core Points of UHPC Exterior Wall Line Expansion Joint Design

1. Material Properties and Expansion Calculation The drying shrinkage rate of UHPC is usually below 0.03%, but it must be accurately calculated in combination with the specific mix proportion and curing process. Through its independently developed UHPC material database, Qinglong Group can use BIM technology to simulate expansion based on parameters such as the temperature gradient at the project site (e.g., a temperature range of -30℃ to 40℃ in northern regions) and sunshine duration, ensuring that the reserved width both meets deformation requirements and avoids overly large gaps that would compromise aesthetics.

2. Joint Construction and Waterproofing Treatment Expansion joint nodes should be filled with elastic sealing materials (such as silicone weather-resistant sealant) to a depth of no less than 2 times the joint width, flush with the UHPC surface. In projects such as the Century Plaza renovation on Nanjing East Road, Qinglong innovatively adopted a "groove + backer rod" construction, which both guarantees space for elastic deformation of the sealant and prevents the sealant from squeezing out under compression, while embedded waterstops raise the waterproofing level.

3. Installation Process and Precision Control The positioning of expansion joints must be coordinated with facade joints, door and window openings, etc. Qinglong uses 3D laser scanning technology for on-site layout with errors controlled within ±2mm; during installation, adjustable connectors absorb construction tolerances to ensure uniform joint width. For super high-rise buildings (e.g., over 200 meters), dynamic displacement caused by wind loads must also be considered, with an additional 10% buffer reserved.

III. Full-Chain Service Ensures the Implementation of Expansion Joint Design

As a national high-tech enterprise and a participant in UHPC standard formulation, Qinglong Group gets involved in expansion joint scheme optimization starting from the detailed design stage. For example, in the Dongguan Women and Children's Activity Center project, parametric design was used to optimize traditional straight joints into curved joints that blend with the architectural texture, meeting functional requirements while enhancing aesthetic effects. In production, automated production lines ensure component dimensional accuracy; during construction, a professional installation team carries out standardized operations; and after-sales service provides 5 years of regular inspection, forming a full-cycle guarantee system of "design-production-construction-maintenance".

The expansion joint design of UHPC exterior wall lines is a comprehensive embodiment of materials science, structural mechanics, and architectural aesthetics. With 28 years of industry experience, Qinglong Group deeply integrates technological innovation with engineering practice, not only providing customers with compliant expansion joint solutions but also achieving a balance between architectural art and structural safety through customized services. Going forward, Qinglong will continue to drive breakthroughs in the application of UHPC materials in architectural decoration, helping to create more landmark projects that combine durability and visual appeal.