How to Prevent Cracking of GRC Components During Setting: Key Techniques and Practical Measures

In the field of architectural decoration, GRC components are widely used in high-end projects such as grand theaters, commercial complexes, and landmark buildings, thanks to their lightweight, high-strength, and richly styled characteristics. However, cracking during setting has long been an industry pain point, affecting not only aesthetics and structural safety but also potentially increasing later maintenance costs. As an industry leader with 28 years of full-chain experience in UHPC/GRC/GRG/GRP materials, Qinglong Group has combined detailed design, manufacturing, and construction practice to develop a systematic anti-cracking solution, providing professional technical support for designers and owners.

Essentially, the setting and cracking of GRC components result from the combined action of internal material stresses and the external environment. From a material perspective, glass fiber reinforced cement undergoes volume shrinkage during the hydration reaction; if shrinkage is restrained or moisture evaporates unevenly, cracks are easily triggered. From a process perspective, oversights such as uneven mixing, unbalanced fiber distribution, and improper curing conditions can also become hidden hazards of cracking. Through participation in formulating the Technical Standard for Building Application of Glass Fiber Reinforced Cement (GRC) (JGJ/T423-2018), Qinglong Group has conducted in-depth research on optimizing material proportions and process parameters, forming a trinity anti-cracking system of "materials-design-construction."

1. Material Proportion Optimization: Building the "Genes" of Crack Resistance
The crack resistance of GRC components begins with the scientific design of material formulations. Qinglong Group uses high-purity Portland cement and alkali-resistant glass fibers (content ≥5%), determining the optimal proportions through orthogonal tests to raise flexural strength to above 20MPa, while incorporating polypropylene fibers and expansion agents to offset cement hydration shrinkage. At the Nanning production base, every batch of materials must pass compressive strength, flexural strength, and drying shrinkage tests to ensure compliance with the Glass Fiber Reinforced Cement (GRC) Decorative Products (JC/T940-2022) standard. Practice shows that the optimized formulation can reduce the incidence of early shrinkage cracks by more than 60%. For more industry information: +WeChat qlfsbl123

2. Detailed Design Control: Reducing Stress Risks at the Source
The design phase is a key line of defense against cracking. For large curved components or special-shaped designs, the Qinglong team uses BIM technology for parametric modeling and simulates stress distribution during setting through finite element analysis, arranging deformation joints and reinforcing ribs in advance. For example, in the Dongguan Women and Children's Activity Center project, GRC cladding panels with spans exceeding 3 meters adopted a "segmented assembly + built-in steel framework" design, which ensured both styling integrity and the release of thermal stress. In addition, the design phase must also specify details such as component thickness (generally ≥15mm) and reinforcement density to avoid cracking caused by unreasonable structure.

3. Refined Production Processes: Full-Process Quality Control
Every step of production and manufacturing requires strict control. Qinglong introduced automated spray-up molding equipment to ensure even distribution of glass fibers; it adopts a combination of steam curing and natural curing, with components cured for 72 hours in a 40℃ constant temperature and humidity environment, then left to rest outdoors for 28 days, allowing the hydration reaction to proceed fully and stably. For complex components, 3D scanning technology achieves mold precision errors of ≤2mm, reducing internal stress after forming. In the Century Plaza renovation project on Nanjing East Road, the production pass rate of translucent GRC components reached 98%, with not a single case of setting cracks. For more industry information: +WeChat qlfsbl123

4. Construction Installation and Later Curing: Key On-Site Anti-Cracking Measures
On-site construction must follow the "flexible installation" principle. Qinglong uses adjustable stainless steel hangers that allow components to undergo slight displacement with temperature changes; before installation, the substrate is checked for flatness, and where errors exceed 5mm, grouting is used for leveling to avoid localized stress concentration. In later curing, components must be covered with wet cloths for 14 days after installation, with spray cooling applied during high summer temperatures to prevent rapid evaporation of surface moisture. These measures have been validated in real estate projects by Poly, China Overseas, and others, effectively ensuring the long-term stability of GRC components.

Preventing setting cracks in GRC components requires material science as the foundation and refined management as the core, running through the entire process of design, production, and construction. As a national high-tech enterprise, Qinglong Group has always combined technological innovation with engineering practice, leveraging 58 patented technologies and full-chain service capabilities to provide customers with "one-stop" solutions from scheme design to after-sales maintenance. In the future, with the development of UHPC/GRC composite technology, Qinglong will continue to explore better anti-cracking solutions, helping realize its mission of "creating aesthetically beautiful buildings" and setting a quality benchmark for the industry.