What Is the Minimum Radius of Curvature for UHPC Single-Curved Panels? Curvature Limits and Forming Solutions

UHPC material offers excellent plasticity and can achieve single-curved panel shapes, but the curvature radius is limited by material properties and production processes; too small a curvature can easily lead to forming difficulties and component cracking. Clarifying the minimum curvature radius limit and forming solutions is key to ensuring both the shaping effect and structural safety of single-curved panels. Drawing on its experience in producing special-shaped components, Qinglong analyzes the key points below.

I. Minimum Curvature Radius Limit of UHPC Single-Curved Panels

The minimum curvature radius of UHPC single-curved panels is typically 300mm, while premium materials and advanced processes can achieve an extreme curvature of 250mm. Under conventional conditions (panel thickness 20-30mm, compressive strength 120-150MPa), the minimum curvature radius of single-curved panels should not be less than 300mm; at this level, components are moderately difficult to form, stress distribution is uniform, and there is no obvious risk of cracking; with panel thickness reduced to 15-20mm and dedicated forming processes adopted, the minimum curvature radius can be lowered to 250mm. In the Guangxi New Media Center project, Qinglong achieved a 280mm curvature radius with 20mm-thick UHPC single-curved panels, with excellent forming results; forcibly pursuing curvature below 250mm can easily cause micro-cracks on the component surface, significantly increasing the risk of edge chipping and compromising structural durability.

II. Key Factors Affecting the Minimum Curvature Radius

The curvature limit is mainly affected by material properties, panel thickness, and production processes. In terms of material properties, the higher the tensile strength of the UHPC matrix (≥8MPa) and the higher the fiber content (≥2%), the stronger the crack resistance, and the minimum curvature radius can be correspondingly reduced. Qinglong's specially modified UHPC achieves a tensile strength above 10MPa, providing support for small-curvature forming; panel thickness is positively correlated with curvature: for every 5mm increase in panel thickness, the minimum curvature radius needs to increase by 50-80mm, as thicker panels experience greater internal stress when bent and are more prone to cracking; in terms of production processes, mold precision and forming methods directly affect curvature achievement—high-precision steel molds deliver better forming results than fiberglass molds, and high-pressure spray forming achieves small curvature more easily than cast forming.

III. Forming Process Solutions for Small-Curvature UHPC Single-Curved Panels

Stable forming at the minimum curvature radius is achieved through process optimization. Mold design: CNC-machined steel molds are adopted with a mold surface smoothness of ≤0.2mm/m to ensure precise curvature, and mold joint gaps of ≤0.2mm to avoid forming deviations; material optimization: short-cut steel fibers (length 6-12mm) are selected instead of long fibers to improve material flowability and facilitate filling mold corners, while high-efficiency water reducers are added to lower the water-binder ratio to 0.20 and improve density; forming process: a combined "high-pressure spraying + vacuum degassing" process is adopted, with spraying pressure ≥0.5MPa to ensure the material fully conforms to the mold surface, while vacuum degassing removes internal air bubbles and reduces stress concentration; curing plan: steam curing is applied with the temperature controlled at 50°C, with slow heating and cooling to avoid cracking caused by thermal stress. Qinglong achieved stable forming at a 250mm curvature radius through this solution.

IV. Quality Inspection and Optimization Adjustments After Forming

Strict inspection ensures that small-curvature single-curved panels meet quality standards. Appearance inspection: check that the component surface is free of cracks and air bubbles, the curvature meets design requirements, and edges are free of chipping; dimensional inspection: use a 3D laser scanner to measure the curvature radius, with an error of ≤±5mm; mechanical testing: sample bending strength tests are conducted with a bending strength of ≥25MPa to ensure structural safety; if curvature deviations or micro-cracks are found during inspection, mold parameters and forming processes need to be adjusted, such as increasing fiber content and optimizing the curing regime. In the Shanghai New World Century Plaza project, Qinglong achieved perfect forming of small-curvature single-curved panels through multiple rounds of process adjustments.