Analysis of UHPC Casting Methods and Key Construction Points

Amid the wave of innovation in building materials, Ultra-High Performance Concrete (UHPC) is becoming the new favorite in landmark buildings and high-end decoration, thanks to its outstanding mechanical properties and design plasticity. As an industry leader with 28 years of full-chain experience in UHPC/GRC/GRG/GRP materials, Qinglong Group knows well that scientific casting technology is the key to unlocking the potential of UHPC materials. This article systematically analyzes mainstream UHPC casting methods and their key construction points, providing designers and engineering parties with a technical guide that combines professionalism and practicality.

The selection of UHPC casting technology must balance material properties with engineering requirements. Currently, mainstream methods fall into three categories: shotcrete casting, formwork casting, and precast casting. The shotcrete casting method sprays UHPC mixture evenly onto the mold or substrate surface through a high-pressure spray gun, making it suitable for complex curved components and large-span structures, with core advantages of reducing air bubbles and improving density. In the Nanjing East Road Century Plaza renovation project, Qinglong adopted this technology to achieve precise forming of translucent concrete components. By adjusting the spray pressure (controlled at 0.3-0.5MPa) and spray angle (45°-60°), the surface flatness and uniform light transmission of the components were ensured.

The formwork casting method is an upgraded version of traditional casting technology, requiring the use of specially made steel molds or elastic molds. This method places extremely high demands on the formwork system. Qinglong achieved mold precision control within ±1mm through its independently developed BIM parametric formwork design system. During construction, attention must be paid to the rheological properties of UHPC, adopting a combination of layered casting (each layer no more than 500mm thick) and high-frequency vibration (vibration frequency 200-300 times/minute) to avoid uneven strength caused by aggregate accumulation. In the Dongguan Women and Children's Activity Center project, Qinglong used the formwork casting technology to complete GRC-UHPC composite curtain wall panels with a maximum size of 8m. Through optimized mix ratios and curing regimes, the 28-day compressive strength of the components exceeded 150MPa.

As the core process of industrialized production, the precast casting method has achieved large-scale application at Qinglong's Guangxi production base. Through the coordinated operation of automatic spreading machines and vibrating tables, combined with steam curing (curing temperature 80-90℃, curing time 4-6 hours), this process shortens the production cycle of precast components to 1/3 of that of traditional methods. Notably, the steel bar embedding in UHPC precast components requires special treatment—Qinglong's original "Fiber-Rebar Collaborative Anchoring Technology" increases interface bond strength by more than 40% by adjusting the steel fiber content (volume ratio 2%-3%) and roughening the rebar surface. This technology has been successfully applied in a UHPC sunshade panel project for a commercial complex in Shenzhen.

Whichever casting method is adopted, quality control during construction is of vital importance. Drawing on 28 years of construction experience, Qinglong has distilled the core points of "Three Controls and One Inspection": controlling raw material metering precision (error ≤±1%), controlling casting environment temperature and humidity (optimal temperature 15-25℃, humidity ≥90%), controlling the curing regime (moist curing for the first 7 days), and non-destructive testing within 24 hours after casting. These measures ensured that the UHPC curtain wall project Qinglong undertook for a Malaysian airport maintained an excellent performance of ten years without cracks under a tropical marine climate.

From conceptual design to finished product delivery, Qinglong empowers the implementation of UHPC projects with its "full-chain service" philosophy. As a national high-tech enterprise and a participant in industry standard setting, Qinglong not only provides material supply but also helps customers achieve a seamless transition from creativity to reality through value-added services such as detailed design optimization, construction simulation, and after-sales maintenance tracking. In the future, as UHPC penetrates widely into municipal, transportation, cultural tourism and other fields, Qinglong will continue to drive industry progress through technological innovation, letting the mission of "Creating Beautiful Architecture" take root in every premium project.