What Is the Minimum Curvature Radius of a Single-Curve GRC Panel? Extreme Bending and the Limits of Qinglong Group's Forming Technology

The minimum curvature radius of single-curved GRC panels depends on four factors: "material properties, panel thickness, reinforcement method, and production process," and its technical boundaries can be continuously pushed forward through material mechanics and process innovation. Based on extensive experiments and project practice, Qinglong Group defines the minimum curvature radius of conventional single-curved GRC panels as 15 times the panel thickness—meaning a 15mm-thick panel can achieve an R225mm bend, and a 10mm ultra-thin panel can even achieve a sharp R150mm bend. In an art installation project in Shenzhen, we adopted a special reinforcement process to successfully achieve an extreme R120mm bend, breaking the industry record. Pursuing the minimum curvature is the ultimate test of material toughness and process precision.

Material Toughness Is the Foundation of Bending Limits

The bending capability of GRC mainly depends on matrix toughness and fiber reinforcement. By optimizing the mix proportion, we keep the compression-to-flexural strength ratio between 3 and 4, and use high-zirconia alkali-resistant glass fiber (ZrO₂≥16%) so that the material exhibits plastic deformation characteristics rather than brittle fracture when bent. In special cases, PVA fiber can be added to further enhance toughness.

Collaborative Design of Panel Thickness and Reinforcement Method

Thin panels more easily achieve small-radius bends, but the problem of insufficient stiffness must be solved. We adopt a "thin panel with ribs" strategy, placing radial stiffening ribs on the non-exposed face of the panel, ensuring bendability while providing sufficient stiffness. In the Dongguan Women and Children's Activity Center project, 6mm-thick decorative profiles achieved an R100mm bend through back ribbing.

Layered Manufacturing Process Controls Cracking Risk

For sharp bends, one-shot molding tends to cause premature cracking on the outer side due to tension. We developed a layered spraying process: a tough base layer with high fiber content (5%) is sprayed first, then covered with a standard face layer, effectively suppressing crack formation. This process enabled the curved column cladding of the Liyuan Hotel in Nanning to achieve a smooth R180mm bend.

Mold Precision and Demolding Technology Assurance

Small-curvature molds demand extremely high machining precision; we use five-axis CNC machining for metal molds, achieving profile surface accuracy of ±0.1mm. During demolding, air-bag assistance or segmented demolding techniques are used to prevent damage caused by suction forces. In the Yirui project in Shenzhen, the demolding success rate for R150mm sharp-bend panels reached 99.5%.

The bending limits of single-curved GRC are constantly being redefined. Through material innovation and process breakthroughs, Qinglong Group provides architects with increasingly free form-making possibilities.