Key Steps in Factory Prefabrication of UHPC Curtain Wall Panels: Process Standards and Quality Control Essentials

Factory prefabrication is the core process for ensuring the precision, performance, and quality of UHPC curtain wall panels. Leveraging 28 years of industrial production experience, Qinglong Group has established a full-process standardized system covering "drawing deepening - mold making - material proportioning - casting and forming - steam curing - finished product testing," with strict quality control points set at every step, ensuring a component pass rate above 99.7%. These processes have been verified in major projects such as Shanghai New World and the Yangshengtang Pharmaceutical Hangzhou Industrial Park.

1. Drawing Deepening and BIM Technology Application: The Foundation of Prefabrication

Drawing deepening must align with production and installation requirements. Qinglong adopts BIM parametric design to convert construction drawings into production detail drawings, specifying component dimensions, hole positions, and embedded part layouts, with errors controlled within ±1mm. Node design is a key optimization focus: complex double-curved surfaces are split into precastable modules to simplify production, and reinforcement layers are reserved at hanger installation positions to enhance connection strength. In the Shanghai New World project, Qinglong used BIM deepening to split the oversized 3245*3530mm UHPC curtain wall panels into 3 modules for prefabrication and then spliced them on site, with installation accuracy controlled within ±2mm. Meanwhile, BIM clash detection was used to avoid conflicts between components and other building systems; in the Yangshengtang Pharmaceutical Hangzhou Industrial Park project, clash detection led to design modifications at 5 component locations, ensuring smooth prefabrication and installation.

2. Mold Making and Precision Calibration: Ensuring Shape and Dimensions

Mold materials are selected according to component type: regular flat panels use steel molds (machining precision ≤±0.5mm), while special-shaped components use GRP molds or polyurethane molds (3D scan modeling). Qinglong customized a polyurethane mold for the hollow-out curtain wall panels of the Ouargla Hotel in Algeria, achieving a 99% shape reproduction rate. After mold making, precision calibration is required: laser rangefinders check the mold's length, width, height, and flatness, with any out-of-tolerance deviations rectified immediately. Mold surface treatment: steel molds are polished (surface roughness Ra≤0.8μm), while GRP molds and polyurethane molds are coated with release agent to ensure smooth component surfaces. In the Shenzhen Yirui Biotechnology Building project, Qinglong calibrated the steel molds three times to ensure the dimensional deviation of the 3000㎡ UHPC curtain wall panels was within ±2mm.

3. Material Proportioning and Mixing: The Core of Stable Performance

Material selection is strictly controlled: P.O52.5 high-grade cement, 0.15-1.2mm quartz sand, 12-15mm steel fibers (2%-3% volume fraction), and custom high-efficiency water reducers are used, and all raw materials must pass testing before use. Mix proportions are precisely controlled: the water-binder ratio is fixed at 0.18-0.20, and electronic metering equipment is used for batching (error ≤±1%). Through its independently developed mix optimization technology, Qinglong keeps UHPC compressive strength stable at 160-180MPa. The mixing process follows three stages: low-speed mixing for 2 minutes (blending aggregates and cement) → medium-speed mixing for 3 minutes (adding steel fibers and reactive powders) → high-speed mixing for 2 minutes (adding water reducer and water), ensuring a uniform mix free of lumps, with air content controlled within 2%.

4. Casting, Forming, and Vibration: Key to Density and Surface Quality

Casting uses the layered casting method, with each layer ≤200mm thick and casting speed controlled at 0.3-0.5m/min to prevent air entrapment. Vibration uses high-frequency, low-amplitude vibrators (frequency 200-300Hz), inserted at spacing ≤300mm with vibration time of 10-15 seconds per point, ensuring the mix is dense and free of bubbles and honeycomb defects. For special-shaped and hollow-out components, vacuum-assisted forming technology (vacuum degree -0.06 to -0.08MPa) is used to extract internal air bubbles; the special-shaped UHPC curtain wall panels of the Shanghai Astronomy Museum were produced with this technology, achieving a surface bubble rate ≤0.3%. After casting, surface finishing is carried out promptly using mechanical troweling plus manual fine finishing to ensure surface flatness ≤2mm/m.

5. Steam Curing and Finished Product Testing: Ensuring Performance Compliance and Factory Release

Curing follows four stages of "pre-curing - temperature rise - constant temperature - cooling": pre-curing (20℃, 4h) → temperature rise (≤10℃/h, up to 50-60℃) → constant temperature (12-18h) → cooling (≤8℃/h). Qinglong uses an intelligent temperature control system to ensure a uniform curing environment and full strength development of components. Finished product testing implements the "three-inspection system": self-inspection (production teams check dimensions and appearance) → mutual inspection (workshop QC checks strength and density) → specialized inspection (third-party testing agencies check durability and safety), with a factory certificate issued after passing inspection. The UHPC curtain wall panels for the Shanghai New World project were tested at 175MPa compressive strength, 38MPa flexural strength, and ±1.5mm dimensional deviation, all meeting standards before leaving the factory.

Factory prefabrication of UHPC curtain wall panels is a systematic project in which every step must strictly follow process standards. As a national high-tech enterprise and a participant in industry standard formulation, Qinglong Group, with its mature production processes, advanced equipment, and strict quality control, has achieved large-scale, refined prefabrication of UHPC curtain wall panels, providing projects with high-quality, highly stable component products and helping to perfectly present building facades.