Technical Limits of Minimum Curvature Radius for Single-Curved GRC Panels: Material Ductility and Forming Process Breakthroughs

The minimum achievable curvature radius of single-curvature GRC panels is jointly constrained by material ductility and forming processes. Through mix proportion optimization and process innovation, Qinglong Group has advanced the minimum stable curvature radius to 300mm (at a panel thickness of 15mm). This breakthrough enables GRC to perfectly render architectural forms such as cylinders and cones, expanding its application boundaries in modern architecture. When the curvature radius is less than 500mm, special mix proportions and precise curing control are required to prevent excessive tension on the outer fibers and slurry accumulation on the inner side.

Material modification enhances ductility. By incorporating polycarboxylate high-range water reducers (water reduction rate ≥30%) and viscosity modifiers, the GRC slurry flow is controlled at 180-220mm, ensuring it fully fills the sharp corners of the mold. Fiber selection is crucial: when R＜500mm, alkali-resistant glass fibers with an aspect ratio of 60-80 must be used, with elongation at break ≥2.5%, 20% higher than ordinary fibers. In an art center project in Shenzhen, Qinglong Group successfully produced column capital components with R=350mm using a segmented pressing process, perfectly realizing the design form.

Precise control of production processes. Small-curvature components require vacuum dewatering technology at a pressure of -0.08 to -0.10MPa to prevent air bubble retention. Demolding time must be strictly controlled until strength reaches 10MPa, as premature demolding causes springback deformation. During the curing stage, custom brackets must be used to maintain curvature stability. Qinglong Group uses digital twin technology to predict shrinkage deformation and compensate for it in advance in mold design, keeping shape errors within L/500.

Extreme curvature requires special construction. When R＜300mm, a composite structure is recommended: an inner glass fiber reinforced gypsum (GRG) base layer provides form support, while the outer layer is a 3-5mm thick decorative GRC facing. This construction ensures form precision while reducing cracking risk. Qinglong Group's technical reserves can meet the demands of various complex curved surfaces, offering architects more creative possibilities.