Do Double-Curved GRC Panels of Different Thicknesses Differ in Forming Difficulty? An In-Depth Analysis of the Correlation Between Thickness and Process Adaptability

Double-curved GRC panels of different thicknesses vary significantly in forming difficulty. This variation is not a simple linear relationship, but involves complex interactions among multiple factors including material rheology, fiber distribution, and demolding stress. Based on extensive engineering practice, Qinglong Group roughly divides double-curved GRC into three ranges by forming difficulty: thin panels (15-20mm), medium-thick panels (20-30mm), and ultra-thick panels (>30mm). Among them, thin panels are prone to deformation, ultra-thick panels are prone to heat accumulation and cracking, and medium-thick panels are relatively balanced but require uniformity control—each category demands a targeted process strategy.

The forming difficulty of thin panels (15-20mm) lies in their low stiffness and susceptibility to deformation. During demolding, handling, and curing, they are highly prone to warping caused by self-weight or external forces. The solution lies in optimizing the distribution of reinforcing fibers—we adopt directional spraying technology to enable the fibers to form an efficient spatial network within the panel plane. Mold design must provide adequate support, and customized curvature brackets must be used immediately after demolding for curing. In addition, thin panels are extremely sensitive to water-binder ratio and shrinkage control, requiring a low-shrinkage cementitious system and high-efficiency water reducers.

Medium-thick panels (20-30mm) are a common thickness for double-curved shapes; the difficulty lies in ensuring uniform thickness across the entire cross-section and consistent fiber distribution while avoiding internal defects. We adopt a layered spraying process with strict control over the thickness and spraying angle of each layer. A single spray layer that is too thick will lead to poor fiber orientation and internal voids. During curing, special attention must be paid to the temperature difference between the interior and exterior, to prevent thermal stress cracks caused by the surface hardening too quickly while internal hydration heat cannot dissipate.

Ultra-thick panels (>30mm) are commonly found in large sculptures or structural components; their core challenges are hydration heat accumulation and drying shrinkage. We take a series of special measures: incorporating a high proportion of mineral admixtures (such as slag powder) into the mix to reduce hydration heat; embedding cooling water pipes for internal cooling; and establishing a reasonable staged curing regime to control the rates of temperature rise and fall. The demolding time for ultra-thick panels must also be significantly extended—they must wait until their core strength has fully developed to resist the adhesion forces and self-weight stress during demolding. Qinglong Group has established corresponding process databases and quality control points for each thickness range, ensuring that precise forming of complex double-curved shapes can be achieved regardless of thickness.