What Are the Key Steps in the Factory Prefabrication Stage of UHPC Curtain Wall Panel Production? Quality Assurance of Standardized Production

The factory precasting stage of UHPC curtain wall panels is the core of quality control, comprising five key steps: raw material inspection, batching and mixing, mold forming, steam curing, and quality testing. Each step must strictly follow process standards and quality requirements to ensure stable component performance, precise dimensions, and flawless appearance. Qinglong, a national high-tech enterprise with automated production lines, runs standardization and refinement through the entire precasting process, providing high-quality precast components for projects such as Yangshengtang Pharmaceutical and Shanghai New World.

Raw material inspection and pretreatment lay a solid foundation for quality. The first step of the precasting stage is incoming raw material inspection. Qinglong conducts strict testing on core raw materials such as cement, quartz sand, alkali-resistant glass fiber, steel fiber, and admixtures: cement must be tested for strength grade (≥52.5) and alkali content (≤0.6%); quartz sand for particle gradation (continuous gradation 0.15-2.36mm) and mud content (≤0.5%); fibers for tensile strength (steel fiber ≥1500MPa, alkali-resistant glass fiber ≥1000MPa) as well as length and diameter deviations; admixtures for water reduction rate (≥30%) and air content. Raw materials that pass inspection require pretreatment: quartz sand is dried to a moisture content of ≤0.5%, fibers are pretreated for dispersion to prevent agglomeration, and cement and mineral admixtures are stored in sealed, moisture-proof conditions. Qinglong's three-tier raw material inspection system ensures every batch of raw materials meets standards, eliminating quality risks at the source.

Precise batching and efficient mixing ensure mixture uniformity. The batching process uses an automated metering system to accurately weigh each component according to the formula, with metering error ≤±1%: the proportions of cementitious materials (cement + mineral admixtures), aggregates, water, admixtures, and fibers must strictly follow design requirements. In Qinglong's UHPC formula, the water-cement ratio is controlled at 0.25-0.35 and the fiber volume fraction at 2%-3%. Mixing uses a twin-shaft paddle mixer following the three-stage process of "dry mixing - wet mixing - fiber dispersion": first, cementitious materials and aggregates are dry-mixed for 2 minutes to ensure uniform blending; then water and admixtures are added for 3 minutes of wet mixing to form a uniform slurry; finally, fibers are added and mixed for 2-3 minutes to ensure even fiber dispersion (agglomerates ≤3mm). The UHPC faux-wood translucent panels for the Shanghai New World project, through precise batching and mixing, achieved a mixture uniformity error of ≤5%, laying the foundation for subsequent forming.

Mold forming and precise control safeguard shape and dimensional accuracy. Before forming, molds must be cleaned and coated with release agent (water-based release agent, applied evenly with no missed spots); the forming process is selected based on component type: flat panels and simple lines use casting, double-curved and complex shapes use high-pressure spraying (pressure 0.3-0.5MPa), and hollowed-out or carved components use precast inlay forming. During forming, vibration is performed for air removal, using attached vibrators (frequency 200-300Hz) or internal vibration pokers to ensure mixture compaction (porosity ≤5%) and avoid bubbles and voids. Qinglong's molds are CNC-machined with dimensional accuracy of ≤±0.5mm, and formed components must be promptly covered with curing film to prevent surface water loss. The UHPC curtain wall panels for the Yangshengtang Pharmaceutical Hangzhou Industrial Park, through high-pressure spray forming and precise vibration, achieved a surface flatness error of ≤±1.5mm/m and dimensional deviation of ≤±2mm.

Intelligent steam curing promotes the development of strength and durability. Formed components are sent into an intelligent curing kiln following the standardized process of "gradient heating - constant temperature curing - slow cooling": heating rate of 5-10°C/h, holding at 90-95°C for 12-16 hours, cooling rate ≤8°C/h, with humidity ≥95% during curing. The intelligent curing kiln monitors temperature and humidity in real time with an error of ≤±2°C/±5%, ensuring full hydration. After curing, Qinglong's UHPC curtain wall panels reach 80% of design strength at 7 days, with 28-day compressive strength ≥150MPa and flexural strength ≥25MPa. For components with complex shapes, curing time is extended to 18-24 hours to prevent insufficient strength caused by incomplete hydration.

Factory quality testing ensures qualified delivery. After precasting, UHPC curtain wall panels undergo full inspection: appearance quality (no cracks, bubbles, or chipped edges/corners), dimensional accuracy (linear dimension deviation ≤±3mm, flatness ≤±2mm/m), mechanical properties (sampling tests for compressive and flexural strength), and durability (sampling tests for frost resistance and impermeability). Components that pass testing are numbered, labeled, and assigned quality traceability records; non-conforming components must be reworked until they meet standards. Qinglong's factory inspection pass rate reaches 100%, and every batch of components comes with a test report to ensure delivery quality.