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

Precision in Timing the Demolding of GRC Components: Key Technical Points Summarized from 28 Years of Industry Experience

In the production of GRC components, controlling the demolding timing is like mastering the heat in cooking—it directly determines the final quality of the product. As an industry-leading enterprise with 28 years of full-chain experience in UHPC/GRC/GRG/GRP materials, Qinglong Group deeply understands the importance of this step for engineering quality. This article systematically analyzes the criteria for determining the optimal demolding timing of GRC components and the influencing factors, providing industry peers with practice-based technical reference.

Core Indicators for Determining the Demolding Timing of GRC Components

Scientifically determining the demolding timing of GRC components requires a multi-dimensional evaluation system. According to the Technical Standard for Building Application of Glass Fibre Reinforced Cement (GRC) (JGJ/T423-2018), which Qinglong Group helped develop, components can be considered basically ready for demolding when their surface hardness reaches a Shore hardness of 65 or above and the curing age meets 12-24 hours (adjusted specifically according to ambient temperature). In actual practice, experienced technicians also apply the finger-press test—pressing the component surface leaves no obvious indentation, and the rebound feel is clear. This combination of traditional methods and modern testing techniques has formed Qinglong's unique "dual-indicator confirmation method".

Four Key Factors Affecting the GRC Demolding Process

Material mix ratio is the fundamental variable determining demolding time. The special low-alkali cement and alkali-resistant glass fibre composite system used at Qinglong's production bases, optimized through 58 patented technologies, shortens the demolding time of standard components by 15% compared with the industry average. For every 10℃ drop in ambient temperature, the demolding time needs to be extended by about 30%; therefore, the intelligent temperature-controlled curing system at the Nanning production base keeps ambient fluctuations within ±2℃. Component thickness and shape are equally critical—for specially shaped GRC components thicker than 100mm, Qinglong adopts a step-by-step demolding process, first loosening the mold and then letting it rest, effectively avoiding cracking caused by stress concentration. As for the curing regime, Qinglong's original "three-stage curing method" (6 hours of pre-curing + 12 hours of steam curing + 24 hours of natural curing) ensures early strength development while laying the foundation for structural stability after demolding.

Differences in Demolding Timing for Different Types of GRC Components

For GRC components used in different application scenarios, demolding timing control must be handled differently. Load-bearing components such as exterior wall cladding panels require higher early strength and usually need to be cured to more than 70% of the design strength; whereas non-load-bearing components such as decorative mouldings can be demolded somewhat earlier provided surface quality is assured. For the double-curved GRC curtain wall panels customized by Qinglong for the Dongguan Women and Children's Activity Center project, stress distribution was simulated using BIM technology, pinpointing the demolding timing to the hour, ultimately achieving zero-damage installation of more than 3,000 components. The project won the Silver Award of the AALBORG WHITE Cup GRC Construction Engineering Innovation Award.

Grasping the demolding timing of GRC components is a systematic project that integrates science and experience, requiring coordinated control of materials, processes, and environment. As a national "Specialized, Refined, Distinctive, and Innovative" enterprise, Qinglong Group has always regarded such key production technologies as its core competitiveness. Through more than 20 years of engineering practice, it has established a full-chain quality control system extending from detailed design to after-sales maintenance. For designers and owners, choosing a GRC manufacturer with mature production processes is an important prerequisite for ensuring project quality—after all, high-quality GRC components depend not only on outstanding design creativity but also on precise control of every production step.