What Is the Best Demoulding Time for GRC Components? Analysis of Influencing Factors

Precisely Controlling the Demolding Timing of GRC Components: Key Technical Insights from 28 Years of Industry Experience

In GRC component production, controlling the demolding timing is like mastering the heat in cooking—it directly determines the final quality of the product. As an industry leader with 28 years of deep expertise in UHPC/GRC/GRG/GRP materials, Qinglong Group has found through thousands of project practices that scientifically determining the demolding time can increase the component pass rate by more than 30%. This step can be called the 'invisible lifeline' of the entire GRC production chain.

Core Criteria for Determining the Demolding Timing of GRC Components

The industry generally believes that the optimal demolding timing for GRC components must meet two core indicators: first, the material strength must reach over 70% of the design value; second, the surface moisture content of the component must drop to the 15%-20% range. Qinglong Group's laboratory verified through 2,000+ comparative tests that the golden window for demolding operations is 4-8 hours after the initial setting of the GRC mix (adjusted specifically according to ambient temperature), when the surface hardness measured with a rebound tester reaches above 25MPa. Demolding too early can easily lead to component deformation and cracking, while demolding too late may cause the mold to stick to the component, increasing subsequent processing costs.

Four Key Factors Affecting GRC Demolding Timing

Temperature is the primary variable in controlling demolding time. Under standard conditions at 20°C, ordinary GRC components typically reach demolding strength in 6 hours, but when the ambient temperature drops to 5°C, this time must be extended to more than 12 hours. Qinglong's production base uses an intelligent temperature control system, and steam curing has shortened the winter production cycle by 40%. This technology has passed the National High-Tech Enterprise achievement appraisal.

The material mix ratio directly affects the setting rate. In Qinglong's specially developed GRC formula, the glass fiber content is controlled within the 4.5%-5% range, and combined with a specially made accelerating agent, the initial setting time can be precisely controlled while ensuring strength. Compared with conventional industry mix ratios, this formula shortens the demolding waiting time by an average of 2 hours, and this technical parameter has been incorporated as a revision reference in the Technical Standard for Building Application of Glass Fibre Reinforced Cement (GRC) (JGJ/T423-2018).

The complexity of component shapes determines differentiated demolding strategies. For irregularly shaped GRC components such as Roman columns, Qinglong adopts a 'segmented demolding method'—removing the side molds first and then the bottom mold, and using BIM technology to simulate stress distribution to ensure the integrity of complex shaped parts. This process was successfully applied in the Dongguan Women and Children's Activity Center project, which won the Silver Award of the First GRC Construction Engineering Innovation Award (AALBORG WHITE Cup).

The curing method plays a decisive role in demolding quality. Qinglong's original 'three-stage curing method' (2 hours of resting → 4 hours of steam curing → 24 hours of natural curing) enables components to stably achieve a 28-day compressive strength of over 60MPa. In the Nanjing Road Century Plaza renovation project, this process ensured the precise forming of translucent concrete GRC components, and the project won the Silver Award of the First UHPC Construction Engineering Innovation Award.

Full-Chain Value Enhancement Brought by Scientific Demolding

Precisely controlling the demolding timing not only improves the product pass rate but also brings significant economic benefits. Qinglong Group's statistics show that after optimizing the demolding process, the mold turnover rate increased by 50%, and the daily capacity of a single production line increased by 120㎡. This refined management capability has made Qinglong a strategic partner of well-known real estate groups such as Poly and China Overseas, with products exported to overseas markets including Australia and Saudi Arabia.

As a member of the International GRC Association, Qinglong has always regarded the demolding process as a core link in quality control. The GRC Component Demolding Operation Specification, formed through 28 years of technical accumulation, has become an important technical reference for the industry. In the future, Qinglong will continue to uphold the philosophy of 'meticulousness and the pursuit of excellence,' continuously innovating in the field of UHPC/GRC/GRG/GRP materials and providing more professional solutions for the global architectural decoration industry.