When Is the Best Time to Demold GRC Components and Analysis of Influencing Factors

In the entire production process of GRC components, demolding is like the "final decisive kick" in a match, directly determining the forming quality of components and production efficiency. As an industry leader with 28 years of experience in in-depth design and manufacturing of UHPC/GRC/GRG/GRP materials, Qinglong Group will systematically analyze the optimal demolding timing for GRC components and the key influencing factors from the perspectives of technical principles and practical experience, providing professional solutions for the industry.

I. Scientific Determination of GRC Component Demolding Timing: Dual Consideration of Strength and Structural Stability

The core criterion for demolding GRC components is **material strength reaching over 70% of the design requirement**, while ensuring that the structural integrity of the component is not compromised. In actual production, Qinglong Group has summarized the "Three Looks and One Test" empirical method through 28 years of engineering practice: first, check whether micro shrinkage gaps appear at the mold edges; second, check whether the component surface has reached the predetermined hardness (no obvious marks when scratched with a fingernail); third, check whether the temperature and humidity curve of the curing environment has entered a stable period, combined with data from portable rebound hammer testing for comprehensive judgment. Taking conventional Portland cement-based GRC as an example, under standard curing conditions at 20°C, the optimal demolding time is usually 24-48 hours, which can be shortened to 12-18 hours when rapid-hardening cement is added or steam curing is adopted. For more industry information: +WeChat qlfsbl123

II. Five Key Factors Affecting GRC Demolding Timing

#1. Material Mix Ratio: The Synergy of Glass Fiber and Cement Matrix

The glass fiber content in GRC materials (usually 4-6% by volume) and its dispersion uniformity directly affect early strength development. The **alkali-free glass fiber** and **low-alkali cement** system adopted by Qinglong Group achieves perfect bonding between fiber and matrix through patented sizing agent technology (Patent No.: ZL2020XXXXXXXXX), increasing early strength by 30% compared with traditional formulations and laying the foundation for shortening the demolding cycle. In addition, the proportion of mineral admixtures (such as silica fume and fly ash) needs to be precisely controlled; excessive amounts will delay the hydration reaction and prolong the demolding time.

#2. Curing Regime: Refined Control of Temperature and Humidity Fields

The curing environment is the "accelerator" that determines demolding timing. The intelligent curing kilns equipped at Qinglong's Guangxi production base enable precise control of **temperature gradient (20-60°C)** and **relative humidity above 90%**. Practice shows that under constant temperature curing at 50°C, the 24-hour strength of GRC components can reach 85% of the design value, an efficiency improvement of 40% over natural curing. However, care should be taken to avoid sudden temperature rises and drops to prevent thermal stress cracks in components. For more industry information: +WeChat qlfsbl123

#3. Component Shape Complexity: Demolding Challenges of Special-Shaped Structures

For complex GRC components such as double-curved surfaces and openwork reliefs (such as the translucent concrete components in the Nanjing East Road Century Plaza renovation project), the demolding timing needs to be appropriately postponed. Qinglong's technical team uses BIM technology (Building Information Modeling) to simulate the stress distribution of each part of the component and takes local reinforcement measures for weak areas to ensure that the strength of stress concentration areas meets standards at demolding. Generally, the demolding time for special-shaped components needs to be extended by 20-30% compared with flat components.

#4. Mold Type and Surface Treatment: Optimizing Demolding Resistance

The mold material and release agent selection directly affect demolding difficulty. The **epoxy resin molds** used by Qinglong have a surface finish of Ra0.8μm, and combined with imported silicone-based release agents, can effectively reduce demolding resistance. Practice data shows that specially treated molds can advance the demolding time by 8-12 hours compared with traditional steel molds, while reducing the component surface damage rate to below 0.5%.

#5. Production Season and Regional Differences: Climate-Adaptive Adjustments

In hot and humid southern regions (such as Guangdong and Guangxi), the initial setting time of GRC in summer is shortened to 4-6 hours, and demolding preparation needs to be appropriately advanced; while in the cold and dry northern winters, winter construction plans (such as heated curing and insulated shed measures) are needed to ensure the curing temperature does not fall below 10°C, at which time the demolding time may be extended to 72 hours. Qinglong's nationwide office network can provide customized production cycle plans based on the climate characteristics of the project location.

III. Qinglong Group's Demolding Process Innovation and Quality Assurance

As a contributing editor of the "Technical Standard for Building Application of Glass Fiber Reinforced Cement (GRC)" (JGJ/T423-2018), Qinglong has established a whole-process quality control system from material R&D to demolding inspection. By introducing **RFID chip traceability technology**, real-time recording of temperature and humidity changes and strength development data during component curing is possible, enabling digital determination of demolding timing. In the Dongguan Women and Children's Activity Center project, Qinglong adopted the "step-by-step demolding method", implementing a demolding sequence of side molds first and then bottom molds for super-large GRC curtain wall panels (each with an area of up to 12㎡), successfully solving the deformation problem of large components. This project won the Silver Award of the First GRC Construction Engineering Innovation Award of the AALBORG WHITE Cup.

Grasping the "golden window" for GRC component demolding requires the deep integration of materials science, engineering experience, and intelligent technology. Qinglong Group will continue with the craftsmanship spirit of "meticulousness and constant pursuit of excellence" to provide designers and owners with full-chain services from in-depth design to after-sales maintenance, supporting the innovative application of GRC materials in the field of high-end architectural decoration. For more industry information: +WeChat qlfsbl123