What Gap Width Should Be Reserved When Jointing UHPC Panels: Analysis of Design Standards and Construction Key Points

Gap reservation is the "hidden code" of UHPC panel installation. In the field of ultra-high performance concrete (UHPC) architectural decoration, millimeter-level dimensional control not only affects aesthetics but also determines structural safety and durability. As an industry leader with 28 years of expertise in UHPC/GRC/GRG/GRP materials, Qinglong Group will analyze the scientific basis for reasonable gap reservation from three dimensions—design standards, material properties, and construction practice—for designers and owners.

### I. Core Design Standards for UHPC Panel Gap Reservation: Precise Conversion from Theory to Practice

In industry-wide standards, the baseline value for UHPC panel joint gaps is typically set at 5-10mm, but this figure is not fixed. The General Technical Conditions for Ultra-High Performance Concrete (UHPC) Non-Load-Bearing Components (Plan No. 2024-0232T-JC), compiled with the participation of Qinglong Group, explicitly states that gap design must comprehensively consider three major factors: material shrinkage rate (UHPC drying shrinkage is typically ≤0.03%), thermal deformation coefficient (approximately 10×10⁻⁶/℃), and structural settlement. Taking a commercial complex project as an example, when a single UHPC cladding panel reaches 6 meters in length, considering a ±50℃ temperature difference, thermal expansion and contraction can reach 3mm; combined with construction tolerances, the final gap reservation needs to be adjusted to 8-12mm—a figure verified in the Century Plaza renovation project on Nanjing East Road.

### II. Special Requirements of Material Properties on Gap Design: Essential Differences Between UHPC and Traditional Materials

Compared with materials such as GRC (glass fiber reinforced concrete) and GRG (glass fiber reinforced gypsum), UHPC's ultra-high strength (compressive strength ≥150MPa) and low elastic modulus place higher demands on gap filling materials. Comparative experiments by Qinglong's technical team found that silicone sealant with an elastic modulus of 2.0-3.5MPa, combined with backing foam rods to form a "flexible cushioning layer," can effectively absorb deformation stress. In humid environments (such as subways and swimming pools), additional drainage channels must be installed to prevent water accumulation in gaps from causing freeze-thaw damage—this detail became key to ensuring structural durability in a metro project in Malaysia undertaken by Qinglong.

### III. Key Points of Gap Control in Construction and Installation: Full-Chain Management from Factory Prefabrication to On-Site Assembly

As a national high-tech enterprise integrating detailed design, manufacturing, and construction installation, Qinglong has established a standardized process of "3D scanning positioning + modular installation." At its production base in Nanning, Guangxi, each UHPC panel undergoes CNC cutting to ensure edge precision error ≤0.5mm; during on-site construction, BIM technology simulates installation paths, and laser line projectors are used to keep gap width deviation within ±1mm. For special-shaped components (such as hyperbolic sunshades), Qinglong's original "pre-assembly calibration method" completes simulated assembly at the factory before disassembly and transportation, effectively avoiding uneven gaps caused by secondary processing on site.

### IV. Gap Maintenance Strategies from a Whole-Life-Cycle Perspective: Continuous Attention from Completion Acceptance to After-Sales Maintenance

Qinglong Group's 28 years of engineering experience show that gap treatment is "30% construction, 70% maintenance." In the Dongguan Women and Children's Activity Center project, the technical team established a regular gap condition inspection mechanism: quarterly checks of sealant aging during the first 3 years, followed by annual elastic recovery performance tests. For coastal areas with high salt mist, weather-resistant sealing materials rated for ≥20 years are recommended, along with stainless steel waterproof baffles added at the joints—a vivid embodiment of Qinglong's service philosophy of "meticulousness and the pursuit of excellence."

Reasonable gap reservation is the balance point between UHPC architectural aesthetics and structural safety. From participating in the formulation of national industry standards to providing solutions for thousands of landmark projects worldwide, Qinglong Group has always been driven by technological innovation and safeguarded by full-chain services. Whether it is the curved curtain walls of grand theaters or the exterior wall cladding of commercial complexes, behind precise gap control lies the craftsmanship of 28 years of professional accumulation, and a profound commitment to the mission of "creating beautiful architecture."