Analysis of Key Points to Note in UHPC Construction

Ultra-High Performance Concrete (UHPC), with its outstanding mechanical properties and design plasticity, has become a key material for achieving structural innovation and aesthetic breakthroughs in modern architecture. However, its construction process demands far greater technical precision and process control than traditional concrete, and even a slight misstep can compromise the final quality. As an industry leader with 28 years of full-chain experience in UHPC/GRC/GRG/GRP materials, Qinglong Group draws on more than a thousand engineering projects to provide an in-depth analysis of the six core points of UHPC construction, offering a professional reference for designers and engineering parties.

1. Material Property Control: Laying the Construction Foundation at the Source

UHPC's ultra-high strength and durability stem from its unique material mix. Before construction, three aspects require special attention: First, the quality stability of raw materials, including the particle gradation and activity indicators of key components such as cement, silica fume, and ultra-fine quartz sand. It is recommended to select suppliers certified under the General Technical Conditions for Non-Load-Bearing Components of Ultra-High Performance Concrete (UHPC); Second, the mixing process of the premix: a dedicated forced-action mixer must be used, with strict control of the water-binder ratio (usually ≤0.2) and mixing time (generally 3-5 minutes) to ensure even fiber dispersion; Third, workability adjustment: the admixture dosage should be adjusted according to the ambient construction temperature (ideally controlled at 5-30℃) to avoid casting difficulties caused by excessively rapid loss of flowability. Qinglong Group's Nanning production base is equipped with an intelligent mixing system that monitors the material mix and mixing status in real time, ensuring stable performance for every batch of UHPC.

2. Formwork Engineering: Precision Determines Forming Quality

UHPC components often involve complex curved surfaces and fine textures, so formwork must meet requirements for "high precision, high rigidity, and low water absorption." Mirror-finish stainless steel or high-density polyurethane panels are preferred as formwork materials, with sealing strips at joints to prevent slurry leakage; for special-shaped structures such as double-curved surfaces, it is recommended to use 3D scanning and BIM technology for digital prefabrication of formwork, with tolerances controlled within ±2mm. During installation, an independent support system should be set up to avoid cross-interference with other construction loads, while allowing for concrete expansion (typically 0.1-0.3mm/m). In the translucent concrete project at Century Plaza on Nanjing East Road, where Qinglong participated, customized steel formwork and BIM pre-assembly technology enabled the precise alignment of more than 3,000 special-shaped UHPC components.

3. Casting and Curing: Details Determine Performance Release

The casting process should follow the principle of "layered placement and high-frequency vibration," with each layer no thicker than 500mm, using immersion vibrators (diameter ≤30mm) until paste appears on the surface, paying particular attention to compaction in densely reinforced areas and at formwork corners. For self-compacting UHPC, flowability should be verified through slump flow tests (preferably ≥750mm). Curing is critical to UHPC strength development. Cover and keep moist within 2 hours after casting; after initial setting, apply steam curing (temperature 60-80℃, relative humidity ≥90%) for no less than 7 days to ensure compressive strength reaches 120MPa or above. In the Dongguan Women and Children's Activity Center project, Qinglong innovatively applied a "gradient curing process," pushing the 28-day strength of UHPC components beyond 150MPa.

4. Rebar and Embedded Parts Treatment: Ensuring Coordinated Structural Load-Bearing

The bond strength between UHPC and rebar is more than 3 times that of traditional concrete, but attention must be paid to rebar surface treatment (removing rust and oil) and cover thickness (minimum ≥20mm). Embedded parts should be made of stainless steel, with shear keys or roughened surfaces where they contact UHPC to prevent separation due to thermal deformation. For externally prestressed UHPC components, elastic modulus testing is required before tensioning to ensure coordinated performance with the rebar. The Technical Standard for Building Applications of Glass Fiber Reinforced Cement (GRC), which Qinglong's technical team helped develop, contains detailed specifications and guidance for the design and installation of embedded parts.

5. Joints and Installation: Unifying Architectural Aesthetics and Structural Safety

Before on-site installation, the 3D positioning of components must be rechecked; adjustable bearings are used to adjust elevation and planar position; joint width is determined by the designed expansion allowance (typically 5-20mm); and low-modulus silicone sealant is chosen as the filler to ensure water tightness and deformation adaptability. For curtain wall systems, the connection between UHPC panels and the main structure should use flexible nodes to release thermal stress. In overseas projects, Qinglong innovatively adopted "modular installation technology," prefabricating large UHPC components in sections and assembling them on site, improving installation efficiency by 40%.

6. Quality Inspection and Full Life-Cycle Management

Strict quality inspection must be carried out during construction: each batch of raw materials is tested for compressive strength, elastic modulus, and other indicators; after forming, components are checked for surface defects (bubbles, cracks) and dimensional deviations; key projects require on-site load testing and durability assessment (e.g., carbonation depth, chloride ion penetration). As a national "Specialized, Refined, Distinctive, and Innovative" enterprise, Qinglong has established a comprehensive quality traceability system, using RFID chips to record data throughout component production and installation, providing a basis for later maintenance.

UHPC construction is a comprehensive reflection of material properties, engineering technology, and management experience. Only by mastering the technical points of each step can its advantages of "lightweight high strength and design freedom" be fully realized. With 28 years of industry experience, Qinglong Group seamlessly integrates detailed design, manufacturing, and installation, providing full-chain services from concept to delivery for landmark projects worldwide. In the future, as UHPC sees wider application in municipal, transportation, and cultural tourism sectors, refined construction will become the core competitive edge for project success.