How to Prevent Cracking of GRC Components During Setting: Research on Key Technologies and Practical Measures

In the field of architectural decoration, GRC components, with their lightweight, high-strength, and richly shaped characteristics, have become the "beauty ambassadors" of numerous landmark buildings. However, cracking during the setting process is like a hidden "quality trap"—it not only affects aesthetics and structural safety, but may also drive up project costs. As an industry leader with 28 years of deep expertise in UHPC/GRC/GRG/GRP materials, Qinglong Group, drawing on full-chain technical experience from material formulation to process control, has built a systematic anti-cracking solution that provides solid assurance for the stable quality of GRC components.

Root-Cause Analysis of GRC Component Setting Cracks: The Dual Challenge of Materials and Process

The setting cracks in GRC components are not caused by a single factor, but result from the combined effects of material properties, environmental conditions, and construction techniques. From a material perspective, the chemical shrinkage and drying shrinkage stresses generated during cement hydration, if not released in time, can easily trigger micro-cracks; insufficient interfacial bond strength between glass fibers and the cement matrix can also lead to stress concentration. In terms of environmental factors, extreme conditions such as high temperatures, strong winds, and sharp temperature differences accelerate moisture evaporation and disrupt the balance of hydration reactions. In addition, process issues such as unreasonable mold design and the absence of a curing regime further amplify the risk of cracking. While undertaking major projects such as the Dongguan Women and Children's Activity Center and the Nanjing Road Century Plaza, Qinglong Group, through tracking and analyzing thousands of GRC components, summarized a trinity anti-cracking technical system of "material optimization – process control – environmental adaptation."

Breakthroughs in Materials Science: From Formula Optimization to Fiber Reinforcement Technology

Material innovation is the core of solving the problem of GRC setting cracks. In response to the shrinkage characteristics of cement-based materials, Qinglong Group's R&D team adopted "dual admixture technology"—compounded incorporation of fly ash and mineral powder—which not only reduces hydration heat, but also refines the pore structure through secondary hydration reactions, keeping the drying shrinkage rate within 0.03%. For fiber reinforcement, alkali-resistant glass fibers with an alkali content below 0.8% were selected and applied using a three-dimensional random distribution process, precisely controlling fiber content at 4.5%–5% to ensure more than 8,000 fibers per cubic centimeter of GRC material, significantly improving matrix toughness. Compared with traditional GRC, Qinglong's optimized material achieves a flexural strength of up to 22 MPa and a 40% improvement in crack resistance. This technical achievement has passed the Guangdong Province Science and Technology Achievement Appraisal and has been applied to shaped curtain wall components for a landmark project in Saudi Arabia.

Full-Process Quality Control: Closed-Loop Management from Mold Design to Intelligent Curing

Superb craftsmanship is the key safeguard against cracking. Qinglong Group introduced BIM technology for parametric mold design, using PU molds with matched elastic modulus for components with complex curved surfaces to reduce stress damage during demolding. In the mixing stage, planetary mixers are used to achieve uniform material blending, with mixing time strictly controlled at 3–5 minutes to ensure fibers are dispersed without clumping. In the forming stage, vacuum vibration forming technology raises component compactness to over 98% and reduces internal porosity. The curing process breaks through traditional models with an innovative "three-stage intelligent curing" approach: during the initial setting period (0–6 hours), 90% humidity and a constant temperature of 20°C are maintained; during the hardening period (6–48 hours), the temperature is gradually lowered to ambient temperature; during the curing period (7–28 days), slow drying is achieved by combining spraying with covering. This process system keeps the cracking rate of Qinglong GRC components below 0.5%, far lower than the industry average.

Engineering Practice and Industry Value: From Technical Solutions to Standard Setting

As a participating unit in drafting the Technical Standard for Application of Glass Fibre Reinforced Cement (GRC) in Building Works (JGJ/T423-2018), Qinglong Group has transformed its anti-cracking technical experience into industry standards, driving the GRC industry's upgrade from "experience-based" to "technology-based." In the expansion project of the Nanning International Convention and Exhibition Center, facing super-large-span GRC ceiling components (each piece covering an area of up to 12 ㎡), the "prestressed reinforcement + block-by-block casting" technique was adopted to successfully avoid deformation and cracking during setting, and the project won the "China Building Decoration Award." To date, Qinglong GRC products have been exported to more than 10 countries including Australia and Malaysia, demonstrating excellent crack-resistance stability in overseas high-temperature and high-humidity environments—a testament to the universality of the technical solution.

Preventing setting cracks in GRC components requires both precise control of materials science and the systematic accumulation of engineering experience. Founded on 28 years of full-chain practice, Qinglong Group integrates the craftsman spirit of "meticulousness and constant refinement" into every technical detail—not only providing customers with high-quality GRC products, but also leading the industry toward green and precision development through technological innovation and standards output. In the future, as UHPC/GRC composite technology sees deeper application, Qinglong will continue to explore more durable anti-cracking solutions, injecting the power of technology into its mission of "creating beautiful architecture."