What Performance Indicators Must Be Tested Before UHPC Components Leave the Factory? Testing Standards and Acceptance Process Explained

Pre-delivery inspection of UHPC components is the last line of defense for product quality. It must cover core indicators including mechanical properties, dimensional accuracy, surface quality, and durability to ensure components meet design requirements and industry standards. Defining inspection items, standards, and procedures is key to standardized production. Drawing on 28 years of quality inspection experience, Qinglong analyzes the core points of pre-delivery inspection.

I. Core Mechanical Property Inspection Indicators

Mechanical properties are the foundation for the safe use of UHPC components, with key testing focused on compressive strength, flexural strength, and fracture energy. Cube compressive strength is tested with 100mm×100mm×100mm specimens; after 28 days of standard curing, strength must be ≥150MPa, while Qinglong's internal control standard is raised to ≥160MPa. Flexural strength is tested with 100mm×100mm×400mm specimens, with three-point bending test strength ≥25MPa. Fracture energy must be ≥2000J/m² to ensure the crack resistance and impact resistance of components. Each production batch requires 3 groups of test specimens with a sampling ratio ≥3%. Test methods comply with the "General Technical Conditions for Non-load-bearing Ultra-High Performance Concrete (UHPC) Components" standard. Qinglong uses automated compression testing machines to ensure inspection data is accurate and reliable. For example, the UHPC sculpture components for the Shanghai Astronomy Museum achieved a 100% pass rate in mechanical property testing.

II. Dimensional Accuracy and Surface Quality Inspection

Dimensional accuracy directly affects installation results, while surface quality determines the decorative effect, and inspection standards are clearly defined. Dimensional inspection covers length, width, thickness, and diagonal deviations. For flat panel components, length deviation must be ≤±3mm, thickness deviation ≤±2mm, and diagonal deviation ≤±4mm; Qinglong uses laser rangefinders for measurement with an accuracy of ±0.1mm. Surface quality is inspected through a combination of visual examination and touch. Surfaces must be free of cracks (width ≤0.1mm), air bubbles (diameter ≤3mm, no more than 3 per square meter), chipped edges and corners, and other defects, with surface flatness error ≤2mm/m and texture fidelity for stone-imitating components ≥95%. Non-conforming components must be repaired or scrapped. Qinglong applies a "dual-person re-inspection" system for surface inspection to ensure accurate results. For example, the UHPC components for the Yangshengtang Pharmaceutical Hangzhou Industrial Park achieved a surface pass rate above 99%.

III. Key Durability Inspection Items

Durability testing ensures the long-term stable use of components and must be targeted according to the service environment. Routine testing includes freeze-thaw resistance (strength loss ≤5% after 200 freeze-thaw cycles), impermeability grade (≥P30), and chloride ion penetration coefficient (≤1×10⁻¹³m/s). For coastal environments, salt spray corrosion resistance testing is added (no obvious corrosion after 500 hours). For industrial environments, chemical corrosion resistance testing is added (strength loss ≤10% after 24 hours of immersion). Qinglong uses specialized testing equipment to complete durability tests, with sampling inspections conducted once per quarter to ensure products meet the requirements of different environments. For example, the UHPC components for the Ouargla Hotel in Algeria passed salt spray corrosion testing and are suitable for coastal environments.

IV. Pre-delivery Inspection Process and Conformity Criteria

Pre-delivery inspection of UHPC components follows the process of "sampling - testing - judgment - release" to ensure standardization and rigor. First, samples are randomly selected by batch, with no fewer than 3 pieces (sets) per batch. Second, tests are conducted on mechanical properties, dimensions, surface quality, and durability, with inspection data recorded. Third, results are judged against standards: a component is conforming only when all inspection items meet requirements; for a failed item, double sampling for re-inspection is allowed, and if re-inspection still fails, the entire batch is scrapped. Finally, a pre-delivery inspection report is issued, and conforming components are marked with an identification number, production date, and conformity mark before leaving the factory. Qinglong has established an inspection data traceability system, with inspection reports for each batch archived for at least 20 years. For example, all UHPC components for the Shenzhen Pingshan High-tech Zone Comprehensive Service Center project come with complete inspection reports, ensuring traceability and providing core evidence for project acceptance.