When is the Best Time to Demold GRC Components?

The best time to demold GRC components is when component strength reaches over 70% of the design strength and the surface moisture content is ≤15%. The timing is mainly affected by temperature, component type, and curing method. Through scientific testing and experienced judgment, Qinglong has achieved a demolding pass rate of 99.8%. Projects such as Shanghai Xinghewan and the Dongguan Women and Children's Activity Center have all achieved damage-free demolding.

1. Meeting Strength Requirements: The Core Indicator for Demolding

Strength is the key to determining demolding timing. Strength requirements: flat components must reach a strength of ≥8MPa, and shaped components (Roman columns, reliefs) must reach ≥10MPa before demolding. Qinglong uses a rebound hammer for on-site testing and demolds only after strength requirements are met. Strength growth pattern: under normal temperature curing (20±5°C), strength can reach 70% of the design value in 72 hours; under high-temperature curing (30-35°C), it can meet the standard in 48 hours. Qinglong adjusts demolding time based on curing temperature. Hazards of insufficient strength: demolding before strength requirements are met can easily cause chipped edges and corners as well as surface damage. Qinglong once demolded 12 hours early on a project, resulting in a 5% component damage rate, and has since strictly followed strength standards.

2. Ambient Temperature and Component Type: Factors for Adjusting Demolding Timing

Temperature and component complexity affect demolding time. Temperature effects: in low-temperature environments (<10°C), cement hydration slows and demolding time needs to be extended by 50-100% (e.g., 72 hours at normal temperature requires 108-144 hours at low temperature). Qinglong uses steam curing in low-temperature environments, shortening demolding time by 30%. In high-temperature environments (>35°C), surface moisture evaporates quickly, so demolding should be done 12-24 hours earlier to avoid surface cracking. Qinglong strengthens moisture-retention curing in high-temperature environments and controls demolding time within 48-60 hours. Component type effects: thin-walled components such as flat panels and simple moldings (thickness ≤20mm) can be demolded early (48-72 hours) once strength requirements are met; complex shapes such as Roman columns and double-curved components (thickness ≥30mm) require an extension of 24-48 hours to ensure internal density. Qinglong adds ultrasonic testing before demolding complex components to confirm there are no internal voids.

3. Qinglong's Demolding Operations and Quality Control

Standardized operations and testing ensure demolding quality. Pre-demolding preparation: clear debris around the mold, check whether the mold connection bolts are loose, and apply release agent (a second coat for complex components). Qinglong uses a dedicated water-based release agent to avoid contaminating component surfaces. Demolding sequence: follow the principle of "non-load-bearing surfaces before load-bearing surfaces, side surfaces before top surfaces," and use dedicated demolding tools (plastic crowbars) to avoid violent prying. Qinglong assigns a dedicated supervisor during demolding, keeping the damage rate below 0.1%. Post-demolding treatment: immediately inspect component surfaces after demolding, promptly repair minor defects, and transfer to the curing stage. Qinglong completes surface repairs within 24 hours after demolding to ensure appearance quality. Project case: the GRC Roman column components (35mm thick) at Fengjingwan, Nanning were demolded after 96 hours of normal temperature curing, with smooth surfaces free of damage, and received high recognition from the client after installation.