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

Precisely grasping the demolding timing of GRC components is the core link that determines product quality and project efficiency. Our 28 years of industry experience show that scientific demolding management can raise the component pass rate by more than 30%.

In the production and manufacturing of new architectural decorative materials such as UHPC/GRC/GRG/GRP, demolding is like the "final decisive step", directly affecting the forming quality, production efficiency, and overall cost of components. As a national-level high-tech enterprise integrating detailed design, manufacturing, and construction and installation, Qinglong Group draws on 28 years of full-chain practical experience to thoroughly analyze the optimal demolding timing of GRC components and its key influencing factors, providing scientific technical guidance for the industry.

Scientific Criteria for Determining the Demolding Timing of GRC Components

Demolding GRC components is not simply a matter of time, but a systematic project that requires comprehensive consideration of material properties and process parameters. According to the Technical Standard for Building Application of Glass Fiber Reinforced Cement (GRC) (JGJ/T423-2018), the optimal demolding timing should meet three core indicators: first, the surface hardness of the component reaches Shore hardness 65 or above, leaving no obvious marks when scratched with a fingernail; second, the peak of cement hydration heat has passed, with the temperature difference between the component interior and the environment controlled within 25°C; third, trial demolding tests confirm that the component edges and corners are free of damage and the surface shows no mold sticking. In the standardized operations at Qinglong's Guangxi production base, under normal-temperature curing conditions (20±5°C), ordinary GRC components are demolded within 24-48 hours, while complex-shaped GRG components require more than 72 hours. Optimized through 58 patented technologies, this parameter shortens the curing cycle by 15% compared with the industry average.

Four Key Factors Affecting GRC Demolding Quality

The material mix ratio is the fundamental variable in determining demolding timing. Through orthogonal experiments, Qinglong's R&D center found that each 0.5% increase in glass fiber content can improve demolding strength by 8-12%, but exceeding 5% reduces workability and actually increases demolding difficulty. In production practice, we use a glass fiber content of 4.2% combined with a specially formulated low-alkali cement, achieving optimal demolding performance while ensuring strength. Control of ambient temperature and humidity is equally crucial. In the overseas project in Malaysia, for high-temperature environments above 35°C, Qinglong innovatively adopted an intelligent mist curing system, stabilizing the relative humidity at 90%±5%, successfully solving the problem of demolding cracking of GRC components in tropical regions caused by excessively rapid water evaporation.

Mold technology and release agent selection directly affect operational feasibility. Qinglong's self-developed ABS composite molds achieve a surface finish of Ra0.8μm; combined with water-based release agents, demolding resistance is reduced by 40%, making them especially suitable for complex curved components such as GRP daylighting canopies. It is worth noting that the release agent formula needs to be adjusted for different seasons: using antifreeze release agents in winter prevents release agent failure at low temperatures, a detail fully verified in key projects such as the Nanjing East Road Century Plaza renovation.

The curing system is the core link in controlling demolding timing. Qinglong's "three-stage curing method" — keeping components at rest during the initial setting period (0-6h), applying steam curing (50-60°C) during the final setting period (6-24h), and natural cooling before demolding (24-48h) — enables the demolding strength of components to stably reach above 15MPa, improving efficiency by 20% over traditional curing methods. This refined curing management is the key guarantee behind Qinglong's annual production capacity of 600,000 square meters.

Full-Chain Value Brought by Scientific Demolding Management

Mastering the optimal demolding timing delivers multiple values for project implementation: In the Dongguan Women and Children's Activity Center project, precisely controlling the demolding time of GRC decorative lines improved on-site installation efficiency by 25% and reduced rework costs caused by dimensional deviations by about 8%. For real estate developers, optimizing the demolding process shortens production cycles, and combined with Qinglong's BIM modular installation technology, compresses the overall project schedule. For designers, stable demolding quality ensures the precise presentation of complex shapes such as hyperbolic surfaces and openwork reliefs; for example, in a cultural center project, more than 2,000 specially shaped GRC curtain wall panels achieved a first-time demolding pass rate of 98.7%.

As a Vice Chairman Unit of the China GRC Association, Qinglong has always treated the demolding process as a key node in quality control, forming a standardized operating system through 28 years of technological accumulation. Going forward, we will continue to rely on the R&D strength of our provincial engineering technology center to explore intelligent demolding technology for UHPC/GRC composite materials, providing more solid technical support for fulfilling our mission of "Creating Beautiful Architecture" and joining hands with industry partners to promote the high-quality development of new architectural decorative materials.