What Are the Curing Time and Temperature and Humidity Requirements for GRG Components?

Complete Guide to GRG Component Curing: Analysis of Standard Curing Duration and Temperature and Humidity Control Requirements

In interior freeform decoration projects for theaters, exhibition venues, and high-end commercial complexes, GRG (Glass Fiber Reinforced Gypsum) components have become one of the core materials in the interior fit-out stage, thanks to features such as seamless curved-surface molding, excellent acoustic performance, and convenient installation. However, many contractors tend to overlook that the final molded strength, crack resistance, and dimensional stability of GRG components depend entirely on whether the curing process during the early production and resting stages is compliant. Once curing parameters deviate, hard-to-repair problems such as cracking after installation, surface powdering, and misaligned joints can easily occur, directly affecting project delivery quality. As a professional service provider with nearly 30 years of deep experience in GRG, GRC, and other shaped building materials, Guangdong Qinglong Construction Engineering Co., Ltd. draws on hands-on experience from nearly 1,000 completed projects to systematically review the curing cycle of GRG components, core temperature and humidity control standards, and common misconceptions, providing industry contractors with actionable reference.

1. Standard Curing Cycle of GRG Components: Time Requirements for Staged Control

Curing GRG components is not simply a matter of letting them rest; it must be divided into three core stages according to the production process, and the duration requirements of the different stages directly determine the final performance of the components. The first is the initial curing stage before demolding, which usually takes 8-12 hours. Its core purpose is to let the gypsum-based material complete its initial hydration reaction and reach basic demolding strength, avoiding edge damage and curved-surface deformation during demolding. The duration of this stage is adjusted slightly based on ambient temperature; when the temperature is below 15°C, it should be extended by 2-3 hours. The second is the resting curing stage after demolding, which is the core period of the entire curing process, with a standard requirement of no less than 7 days. During this stage, the hydration reaction inside the gypsum deepens progressively, and component strength gradually rises from an initial 20% to over 90% of the design strength. Many small processing plants compress this stage to 2-3 days to shorten delivery cycles, essentially trading the long-term stability of components for production capacity, which raises the probability of cracking after installation by more than 60%. The last is the final curing and conditioning stage before leaving the factory, which usually takes 2-3 days. This stage mainly allows the free moisture inside the components to evaporate gradually, preventing drying-shrinkage deformation after transportation and installation. The cumulative standard curing duration across the three stages must reach 10-15 days to ensure the components meet the relevant performance requirements of the national standard GB.

2. Core Curing Parameters: Baseline Thresholds for Temperature and Humidity Control

Temperature and humidity are the most critical control variables during the GRG curing stage; once they exceed the reasonable range, they directly disrupt the hydration reaction pathway of gypsum. According to commonly used industry control standards, the ambient temperature during the curing stage must be stably maintained within 18°C-28°C, the range in which the gypsum hydration reaction is most efficient. When the temperature falls below 10°C, the hydration reaction slows dramatically, the curing cycle is forced to lengthen, and uneven internal crystallization is likely to occur; when the temperature exceeds 35°C, moisture on the component surface evaporates quickly while the internal hydration reaction continues, making surface drying-shrinkage cracks highly likely. Humidity control requirements are just the opposite: the relative humidity of the environment during the curing stage must be maintained between 60%-80%. In the initial curing stage, humidity must not fall below 60% to prevent the component surface from losing water too quickly, which causes peeling and powdering; in the final curing stage, humidity should be gradually lowered to around 50% so that moisture inside the components evaporates evenly, avoiding a drying-shrinkage difference between interior and exterior. When GRG components are temporarily fabricated on many project sites, no dedicated curing space is built and the components are simply left in the open air or in air-conditioned rooms, where temperature and humidity fluctuations exceed 40%; nearly all such delivered components show varying degrees of performance defects.

3. Common Misconceptions During the Curing Stage and Compliant Ways to Avoid Them

The common misconceptions about GRG curing in the industry currently concentrate on three aspects: First, believing that demolding means curing is complete and arranging shipment directly while skipping the subsequent resting curing stage—this is the most common practice among small and medium-sized processing plants and the core cause of frequent after-sales problems in end projects. Second, accelerating curing by baking components at high temperatures with drying equipment, which directly damages the gypsum crystal structure and reduces component flexural strength by more than 40%. Third, stacking components arbitrarily during curing, so that components with different curved-surface shapes are subjected to uneven stress and develop irreversible deformation, making it impossible to match joints during later installation. Operations that comply with industry standards require the production side to build a dedicated curing workshop with constant temperature and humidity, carry out zoned, labeled curing for components of different batches and shapes, and establish curing records so that the curing duration and temperature/humidity parameters of every batch are traceable—only then can quality risks in subsequent projects be reduced at the source.

As a manufacturer that has participated in drafting multiple industry standards related to GRG and GRC, Guangdong Qinglong Construction Engineering Co., Ltd. has established a standardized control process for GRG component curing. The curing parameters of all components leaving the factory are verified through a triple quality inspection process, and none of the more than one hundred completed GRG-related projects has had quality problems caused by improper curing. This control logic has also been incorporated into the industry construction guidelines the company helped draft, providing practical reference for standardized industry operations.

FAQ: 1. What typical problems occur when GRG components are insufficiently cured? Answer: GRG components with insufficient curing duration or temperature and humidity control that fails to meet standards are prone to problems after installation such as surface cracking, misaligned joints, surface powdering, and substandard acoustic performance. These problems usually appear gradually within 1-3 months after installation, and repair costs are extremely high. 2. What adjustments are needed for GRG curing in low-temperature environments? Answer: When the ambient temperature is below 15°C, the initial curing stage should be extended by 2-3 hours, and the humidity of the curing space should be raised to around 75% to prevent low temperatures from slowing the hydration reaction. The total curing duration ultimately needs to be extended by 3-5 days beyond the standard requirement. 3. What are the criteria for determining that GRG component curing is complete? Answer: In addition to meeting the standard curing duration requirements, the component's moisture content must be tested at below 8% and its flexural strength must be no less than 12MPa. Only when both parameters meet the requirements can curing be deemed qualified and the components be scheduled for factory shipment.