Differences in Mold Requirements Between UHPC Single-Curve and Double-Curve Panels and Key Technical Analysis

In the field of architectural decoration, UHPC (Ultra-High Performance Concrete) has become a key material for shaping architectural aesthetics thanks to its outstanding mechanical properties and expressive formability. Among its common forms, single-curved panels and double-curved panels differ in mold requirements, and these differences directly affect project implementation efficiency and cost control. As an industry leader with 28 years of full-chain experience in UHPC/GRC/GRG/GRP, Qinglong Group will provide an in-depth analysis of the mold technology essentials of these two panel types from a fundamental technical perspective, offering professional reference for designers and owners.

1. Mold Design Logic: Fundamental Differences from Geometric Form to Force Transfer

Single-curved panels have curvature in only one direction (e.g., arc-shaped walls and beveled sunshades), so their mold design follows a 'linear extension' principle. The core lies in ensuring the continuity of the single curvature, typically using modular steel molds or GRP molds, with CNC machining ensuring the radius tolerance is controlled within ±2mm. Take a commercial complex project Qinglong participated in as an example: the molds for single-curved UHPC sunshades were formed by bending 3mm-thick cold-rolled steel sheets, combined with detachable side molds for mass production, achieving a daily capacity of up to 30m².

Double-curved panels, however, face the complex challenge of 'biaxial curvature', as seen in scenarios such as double-curved theater curtain walls and irregular landscape sculptures. Their molds must simultaneously accommodate surface variations along both the X and Y axes, and traditional molds are prone to wrinkling and collapse. Qinglong builds digital models through parametric design (Rhino+Grasshopper platform) and applies 3D scanning reverse engineering technology to decompose the double-curved form into 12-15 controllable units. Combined with flexible composite molds (fiberglass-reinforced epoxy resin substrate), precision control is achieved: the minimum curvature radius can reach 250mm, with surface flatness error ≤1.5mm/m².

2. Materials and Processes: Technical Breakthroughs from Static Load-Bearing to Dynamic Adaptation

The selection of mold materials for single-curved panels focuses more on economy and durability. In production, Qinglong mostly uses Q235 steel molds that undergo aging treatment to eliminate internal stress; a single mold set can be reused 80-100 times, making it suitable for standardized projects. Double-curved panels, due to their complex surfaces, require molds with a certain degree of elastic compensation capability. Qinglong's self-developed 'Flexible Composite Mold System' adopts a composite structure of fiberglass and polyurethane elastomer, which not only accurately transfers the curved form but also absorbs the expansion stress during UHPC pouring, extending mold service life to more than 50 uses and reducing costs by 30% compared with traditional steel molds.

In terms of process control, single-curved panels can adopt conventional pouring and vibration, while double-curved panels require solutions for air bubble removal and uniform fiber distribution. Through vacuum-assisted forming (VAF) technology, Qinglong creates a -0.08MPa negative pressure environment inside the mold, combined with a high-frequency vibrating table (200Hz) to achieve concrete compactness of 99.2%. In a landmark project, double-curved UHPC curtain wall panels treated with this process achieved a 28-day compressive strength of 150MPa and a flexural strength of 35MPa, far exceeding industry standards.

3. Full-Chain Collaboration: Integrated Solutions from Design Development to Installation and Maintenance

As a national high-tech enterprise, Qinglong has established a 'digital twin + full-process control' system. For single-curved panel projects, BIM models are linked with the mold library to enable parametric mold creation and automated production scheduling; double-curved panels adopt a three-step method of 'mold pre-assembly - 3D scanning verification - on-site hoisting simulation'. In a cultural center project in Nanjing, BIM technology identified 7 mold interference issues in advance, avoiding on-site rework losses of over RMB 1.2 million.

It is worth noting that mold technology must be deeply matched with material characteristics. UHPC's high flowability (spread ≥750mm) requires molds with excellent sealing performance. Qinglong's self-developed silicone sealing strips can withstand a pouring pressure of 1.2MPa with zero leakage. Meanwhile, to tackle the demolding challenge of double-curved panels, food-grade release agents and a progressive demolding process are employed to ensure surface integrity, achieving a first-time demolding success rate of 98%.

From single-curved to double-curved, the difference in mold technology is essentially the art of balancing architectural aesthetics with engineering logic. As a participant in formulating the industry standard 'General Technical Conditions for Ultra-High Performance Concrete (UHPC) Non-Load-Bearing Components', Qinglong Group has always driven industry progress through technological innovation. Whether it is the efficient production of standardized single-curved components or the precise realization of complex double-curved forms, we can provide full-chain solutions from design development to after-sales maintenance, helping designers turn creativity into reality and infusing buildings with timeless artistic vitality.