What Are the Common Mold Materials for UHPC Components? Analysis of Their Advantages and Applications

Seizing the Golden Timing for GRC Component Demolding: Technical Essentials and Practical Guide from 28 Years of Industry Experience

In the full production chain of GRC (Glass Fiber Reinforced Concrete) components, demolding is like the decisive final kick, directly determining product precision, surface quality, and production efficiency. As an industry leader with 28 years of experience in detailed design and manufacturing of UHPC/GRC/GRG/GRP materials, Qinglong Group fully understands the critical impact that precise control of demolding timing has on project success. Drawing on the technical expertise of a national high-tech enterprise, this article systematically explains the criteria for determining the optimal demolding timing for GRC components and the six core influencing factors, providing designers, developers, and construction contractors with practical, professional solutions.

Scientific Determination of GRC Component Demolding Timing: The Dual Dimensions of Strength and Process

Determining whether GRC components have met demolding conditions requires a dual evaluation system of "strength compliance + process compatibility." According to the Technical Standard for Building Application of Glass Fiber Reinforced Cement (GRC) (JGJ/T423-2018), which Qinglong Group participated in developing, demolding operations may only be performed once curing has reached at least 70% of the design strength. In actual production, this is typically verified through compressive strength testing of test specimens cured under the same conditions, supplemented by surface hardness checks (no visible marks when scratched with a fingernail) and color changes (showing a uniform natural cement color). For complex shaped components, such as double-curved curtain wall panels or openwork reliefs, the load balance of structural support points must also be additionally evaluated to prevent deformation and cracking caused by localized stress concentration.

Six Key Factors Affecting GRC Demolding Timing and Control Strategies

1. Material Mix Ratio and Fiber Content: The length and content of glass fibers in GRC materials, together with the water-cement ratio of the cementitious material, directly affect early strength development. Through 28 years of formula optimization, Qinglong Group uses a composite system of high alkali-resistant glass fibers (4-5% content) and specialty cement, reducing the demolding time of standard components by 15% compared with the industry average. Practice shows that when fiber dispersion uniformity improves by 20%, the time to reach demolding strength can be advanced by 2-3 hours.

2. Curing Environment Parameters: Temperature, humidity, and curing time form a triangular relationship. In the constant temperature and humidity curing kilns at Qinglong's Guangxi production base, ambient temperature is controlled at 20-25°C and relative humidity at ≥90%, combined with steam curing to accelerate the hydration reaction, allowing components to reach demolding strength within 12-24 hours. Special caution is needed: sudden temperature increases and sharp humidity drops can cause surface cracking—a key issue to guard against in winter production in northern regions.

3. Component Geometry: For large GRC components thicker than 50mm (such as Roman columns and cornice moldings), layered casting and stepped curing should be adopted, with demolding time extended by 30%; thin-walled components (such as 3-5mm thick decorative cladding panels), on the other hand, require mold surface treatment (such as nano release agents) to reduce sticking risk. In Qinglong's translucent concrete project at Century Plaza on Nanjing East Road, BIM technology was used to simulate stress distribution, successfully achieving one-time demolding and forming of 3.6-meter extra-long UHPC-GRC composite components.

4. Mold Type and Surface Treatment: Differences in thermal conductivity among steel molds, GRP (fiberglass) molds, and silicone molds lead to different curing rates. Qinglong's independently developed patented composite mold (Patent No. ZL2023XXXXXX) features a built-in temperature control system that keeps temperature differences across component sections within 5°C, ensuring uniform strength distribution at demolding. Mold surface polishing precision (Ra≤0.8μm) is equally critical, as it directly affects GRC surface texture and demolding resistance.

5. Seasonal and Climatic Conditions: In hot summer environments, rapid moisture evaporation must be prevented, using shading plus mist-spray curing; in cold winter, floor-heating-style curing should be activated to ensure the cement hydration reaction continues. In its Saudi Arabia project, Qinglong successfully solved the demolding challenge at 45°C high temperatures by adjusting retarder dosage and scheduling nighttime construction.

6. Balancing Production Schedule and Quality: Blindly pursuing rapid demolding can lead to insufficient later-stage component strength, while excessive delays increase mold turnover costs. Qinglong optimizes production scheduling through an ERP system, raising mold turnover to an industry-leading 3-4 cycles/week; in the Dongguan Women and Children's Activity Center project, 3,000㎡ of GRC curtain wall panels were delivered with zero rework.

A Full-Chain Demolding Quality Assurance System

As a national specialized, refined, distinctive, and innovative enterprise integrating detailed design, manufacturing, and construction installation, Qinglong Group emphasizes coordination between the demolding process and the preceding and following stages: BIM models optimize component demolding angles at the design stage, RFID chips enable curing process traceability at the production stage, and specialized lifting fixtures are provided at the installation stage to prevent secondary damage after demolding. This full life-cycle management mindset has kept Qinglong's GRC components at a first-time acceptance rate above 99.6% in benchmark projects such as Vanke and Xinghewan.

Precisely grasping the demolding timing of GRC components is, in essence, a comprehensive art of materials science, engineering mechanics, and production management. For 28 years, Qinglong Group has consistently maintained a "meticulous and excellence-driven" attitude, upgrading its demolding processes from empiricism to data-driven standardized procedures. For designers and owners pursuing high-quality architectural decoration effects, choosing a GRC manufacturer with full-chain technical capabilities means choosing reliable assurance from design concept to finished product. Looking forward, as UHPC/GRC composite technology develops, Qinglong will continue exploring more efficient and intelligent demolding solutions, injecting technical momentum into its mission of "creating beautiful architecture."