Key Technical Points and Implementation Strategies for Steam Curing GRC Components in Low-Temperature Environments

Key Technical Points and Implementation Strategies for Steam Curing of GRC Components in Low-Temperature Environments

In the field of architectural decoration materials, GRC (Glass Fiber Reinforced Concrete) is widely used in high-end projects such as grand theaters, commercial complexes, and landmark buildings for its lightweight, high-strength, and richly formable characteristics. However, production quality control of GRC components in low-temperature environments has long been an industry challenge, and steam curing, as a critical step, directly affects the strength development and durability of components. As an industry leader with 28 years of full-chain experience in UHPC/GRC/GRG/GRP materials, Qinglong Group has drawn on the practice of hundreds of low-temperature projects to develop a systematic steam curing technical solution, providing professional solutions for designers and owners.

### Core Challenges of Low-Temperature Environments for GRC Component Production

Low temperatures (typically referring to ambient temperatures below 5°C) significantly slow the cement hydration reaction, leading to slow early strength growth of GRC components and problems such as surface cracking and loose structure. Traditional natural curing under low-temperature conditions requires the curing period to be extended 3-5 times, seriously affecting project delivery efficiency. Qinglong Group laboratory data show that when the ambient temperature drops to 0°C, GRC components without curing measures achieve only 65% of the standard value in 28-day strength, while proper steam curing can raise this figure to over 95%, while also shortening the curing time to 1/3 of the traditional process.

### Four Key Technical Points of GRC Component Steam Curing

**1. Gradient Heating Control Technology** Steam curing in low-temperature environments must strictly follow the three-stage process of "slow heating - constant temperature curing - gradient cooling". Qinglong Group uses an intelligent temperature control system to keep the heating rate at 10-15°C/h, preventing component cracking caused by excessive internal-external temperature differences. In the constant temperature stage (usually 60-70°C), humidity sensors maintain a relative humidity above 90% to ensure full formation of cement gel. This technology was successfully applied in a landmark project in Nanjing, keeping the surface flatness error of GRC curtain wall panels within 2mm/m.

**2. Mold Preheating and Component Wrapping Process** For large GRC components (such as shaped decorative lines over 6 meters long), Qinglong innovatively combines mold preheating (40-50°C) with wrapping in heat-resistant cotton quilts. This reduces steam heat loss and keeps the temperature difference between the core and surface of components within 5°C. During winter construction in Harbin, this process raised the first-pass qualification rate of 5,000㎡ of GRC exterior wall panels to 98%, far exceeding the industry average.

**3. Steam Quality and Flow Regulation** Saturated steam is the ideal heat source for GRC curing. Qinglong removes condensate and impurities through steam purification devices to ensure steam dryness ≥95%. Steam flow is also dynamically adjusted according to component thickness: thin panels below 30mm use intermittent steam supply, while thick panels above 60mm use continuous steam supply combined with circulation fans to ensure uniform heat penetration. This technology has been included as a compilation reference in the Technical Standard for Architectural Application of Glass Fiber Reinforced Cement (GRC) (JGJ/T423-2018).

**4. Post-Curing Slow Cooling Treatment** Sudden cooling causes thermal stress in GRC components. After curing is completed, Qinglong adopts a phased cooling method: first closing the steam valve for 30 minutes of natural cooling, then starting the ventilation system to bring the component temperature within ±10°C of ambient temperature. This measure effectively solved the problem of post-demolding cracking of components in low-temperature environments in a commercial complex project in Shenyang, saving more than 2 million yuan in rework costs.

### Qinglong Group's Full-Chain Steam Curing Implementation Support

As a national high-tech enterprise and a drafting unit of GRC industry standards, Qinglong controls steam curing quality throughout the whole process from design to production to construction. In the detailed design stage, BIM technology is used to simulate the temperature field distribution of components in low-temperature environments; the production stage is equipped with 28 automated curing kilns to achieve 24-hour continuous operation; during construction and installation, special technical briefings are provided to ensure that secondary curing after on-site assembly meets standards. To date, Qinglong GRC components have passed 500 freeze-thaw cycle tests at -40°C, with performance indicators far exceeding national standards, and are widely used in key projects in severe cold regions such as Northeast and Northwest China.

Steam curing of GRC in low-temperature environments is a combination of technology and experience. Based on 28 years of industry experience, Qinglong Group deeply integrates material characteristics, equipment innovation, and process optimization to provide reliable low-temperature production solutions for the architectural decoration field. Going forward, Qinglong will continue to promote technological breakthroughs of GRC materials in extreme environments and, with the mission of "Creating Aesthetic Architecture", help more landmark projects achieve a perfect unity of design and quality.