When Is the Best Time to Demold GRC Components? Demolding Timing Criteria and Operating Standards

The timing of GRC component demolding directly affects surface quality and structural strength. Demolding too early can easily cause breakage and deformation, while demolding too late may cause the component to stick to the mold, increasing demolding difficulty. Scientifically determining the demolding timing and standardizing operations is key to ensuring GRC component quality. Drawing on 28 years of production experience, Qinglong analyzes the core points.

1. Core Criteria for Determining Demolding Timing

The demolding timing should be determined comprehensively based on strength development and environmental conditions. The core indicator is the surface strength of the component: scratch the component surface with a fingernail—there should be no obvious scratch (surface hardness ≥ 2.5MPa), and the component edges should show no chipped corners or damage. Under normal conditions (temperature 20°C, humidity 70%), flat panel components require no less than 24 hours before demolding, while irregular complex components need to be extended to 36-48 hours; in high-temperature environments (temperature >30°C), this can be shortened to 18-20 hours, and in low-temperature environments (temperature <10°C), it should be extended to 48-72 hours. Qinglong's test data show that with demolding after 24 hours at 20°C, the compressive strength of components can reach more than 50% of the design value, meeting the demolding strength requirements.

2. Demolding Timing Differences Across Environments and Component Types

Environmental conditions and component types determine adjustments to the demolding timing. In the high-temperature, high-humidity summer environment, cement hydration is fast, so the demolding time can be moved up appropriately, but the surface strength must meet the standard to avoid surface dusting caused by premature demolding; in the low-temperature, dry winter environment, steam curing or thermal insulation measures are required, and demolding should wait until the component strength reaches more than 55% of the design value. Qinglong adopted steam curing in its northern projects, controlling the demolding time at around 48 hours; for small simple components (such as moldings and window surrounds), the demolding time can follow conventional standards, while large irregular components (such as double-curved panels and sculptures) require extending the demolding time by 20%-30% due to their complex forming, to ensure structural stability. The demolding time for the double-curved GRC components of the Guangxi New Media Center all exceeded 48 hours.

3. Standardized Demolding Procedures and Key Points

Standardized demolding operations can prevent component damage. Before demolding, first clear away debris around the mold and check whether there is any adhesion where the component contacts the mold. If there is adhesion, gently pry it loose with wooden wedges; forcibly striking with metal tools is strictly prohibited. The demolding sequence follows the principle of "non-load-bearing parts first, then load-bearing parts; side surfaces first, then front surfaces." Large components use multi-point synchronized demolding to avoid deformation caused by excessive force at a single point. During demolding, use dedicated lifting devices with lifting points consistent with the design, and lift slowly (≤0.5m/min) to prevent the components from hitting the mold. In the Shenzhen Pingshan High-Tech Zone project, Qinglong controlled the component breakage rate below 0.3% through standardized demolding operations.

4. Post-Demolding Treatment and Curing

Timely treatment and curing after demolding ensure stable component performance. Immediately after demolding, inspect the component surface quality, and promptly repair any minor scratches or pitted surfaces with a special repair agent; apply a curing agent to the component surface or cover it with geotextile, maintain the ambient humidity at ≥90%, and continue curing for 7-14 days to ensure continued strength development; transfer the components to the designated storage area and avoid placing them directly on rough ground to prevent surface abrasion. Through refined post-demolding treatment, Qinglong ensures that the factory pass rate of GRC components remains stable at above 99%, laying a solid foundation for subsequent installation.