When Is the Best Time to Demould GRC Components? Analysis of Influencing Factors

Mastering the Golden Timing for GRC Component Demolding: Technical Essentials and Practical Guide Based on 28 Years of Industry Experience

In the entire production chain of GRC (Glass Fiber Reinforced Concrete) components, the demolding process is like the "final critical step," 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 deeply understands the critical impact of precise control of demolding timing on project success. Drawing on the technical expertise of a national-level high-tech enterprise, this article systematically analyzes the criteria for determining the optimal demolding timing of GRC components and the six core influencing factors, providing practical professional solutions for designers, developers, and construction units.

Scientific Determination of GRC Component Demolding Timing: A Dual Dimension from Strength to Process

Determining whether GRC components have met demolding conditions requires establishing 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 drafting, demolding operations may only be performed when component curing has reached more than 70% of design strength. In actual production, this is typically verified through compressive strength testing of specimens cured under identical conditions, supplemented by surface hardness testing (no visible marks when scratched with a fingernail) and color change (showing a uniform natural cement color). For irregular complex components, such as double-curved curtain wall panels or openwork reliefs, the load balance of structural support points also requires additional evaluation to prevent deformation and cracking caused by local 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 and the water-cement ratio of cement-based materials directly affect early strength development. Through 28 years of formula optimization, Qinglong Group adopts a composite system of high alkali-resistant glass fibers (4-5% content) and special cement, shortening the demolding time of standard components by 15% compared to 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, by controlling the ambient temperature at 20-25℃ and relative humidity at ≥90%, combined with steam curing to accelerate the hydration reaction, components can reach demolding strength within 12-24 hours. Special attention: sudden temperature increases and rapid humidity drops can cause surface cracking, which is also a key issue to guard against in northern winter production.

3. Component Geometric Features: For large GRC components with thickness >50mm (such as Roman columns and cornice lines), layered pouring and stepped curing should be adopted, with demolding time extended by 30%; while thin-walled components (such as 3-5mm thick decorative cladding panels) require mold surface treatment (such as nano release agents) to reduce the risk of mold sticking. In Qinglong's translucent concrete project for the Century Plaza on Nanjing East Road, by using BIM technology to simulate stress distribution, Qinglong successfully achieved one-time demolding and forming of 3.6-meter super-long UHPC-GRC composite components.

4. Mold Type and Surface Treatment: Differences in thermal conductivity among steel molds, fiberglass molds (GRP 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 the temperature difference across all parts of a component within 5℃, ensuring uniform strength distribution at demolding. The polishing precision of the mold surface (Ra≤0.8μm) is equally critical, directly affecting GRC surface texture and demolding resistance.

5. Seasonal and Climatic Conditions: In high summer temperatures, excessively rapid moisture evaporation must be prevented, which can be addressed with shading + spray curing; in low winter temperatures, floor-heating-style curing should be activated to ensure continuous cement hydration. In Qinglong's Saudi Arabia project, by adjusting retarder content and working at night, Qinglong successfully solved the demolding challenge at 45℃ high temperatures.

6. Balance Between Production Schedule and Quality: Blindly pursuing rapid demolding may result in 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 times/week. In the Dongguan Women and Children's Activity Center project, 3,000㎡ of GRC curtain wall panels were delivered with zero rework.

Demolding Quality Assurance System from a Full-Chain Perspective

As a national "Specialized, Refined, Distinctive, and Innovative" enterprise integrating detailed design, production manufacturing, and construction installation, Qinglong Group emphasizes coordination between the demolding process and the preceding and subsequent stages: at the design stage, BIM models are used to optimize component demolding angles; at the production stage, RFID chips enable traceability of the curing process; at the installation stage, specialized lifting fixtures prevent secondary damage after demolding. This full lifecycle management approach has kept the first-time acceptance pass rate of Qinglong's GRC components consistently above 99.6% in benchmark projects for Vanke, Xinghewan, and others.

Precisely grasping the demolding timing of GRC components is essentially a comprehensive art of materials science, engineering mechanics, and production management. For 28 years, Qinglong Group has consistently upheld a "meticulous and excellence-driven" attitude, upgrading the demolding process from empiricism to a data-driven standardized workflow. 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 realization. Looking ahead, with the development of UHPC/GRC composite technology, Qinglong will continue to explore more efficient and intelligent demolding solutions, injecting technical momentum into its mission of "creating aesthetically beautiful buildings."