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

In the field of architectural decoration, the quality of GRC components directly affects a building's aesthetics and safety, and cracking during the setting process has long been a focal concern of the industry. As an industry leader with 28 years of full-chain experience in UHPC/GRC/GRG/GRP materials, Qinglong Group understands that cracking in GRC components not only affects project schedules but also compromises a building's durability and artistry. Drawing on Qinglong's practical experience in detailed design, manufacturing, construction, and installation, this article systematically explores the key technologies and practical measures for preventing setting-related cracking in GRC components, providing professional solutions for designers, owners, and industry peers.

Analysis of the Causes of Setting-Related Cracking in GRC Components: Multidimensional Challenges from Materials to Processes

GRC (Glass Fiber Reinforced Concrete) is a new type of building material composed of cement, glass fibers, fine aggregates, and other components; its setting process is a complex stage in which physical and chemical changes intertwine. The causes of cracking are mainly concentrated in three aspects: shrinkage stress concentration caused by unbalanced material proportions, such as excessive cement content or insufficient fiber dosage; uneven internal structure caused by production process defects, such as disordered fiber distribution resulting from insufficient mixing; and temperature and humidity gradients caused by uncontrolled curing environments—especially under high-temperature dry conditions or sudden low-temperature changes, when the difference in shrinkage rates between a component's surface and interior becomes too great. While undertaking landmark projects such as the Dongguan Women and Children's Activity Center, Qinglong found that over 90% of cracking problems can be avoided in advance through full-process control, which forms the practical basis of the "prevention first" philosophy.

Material Science and Mix Ratio Optimization: The Underlying Logic of Crack Resistance in GRC Components

The core of preventing cracking begins with the scientific design of material formulations. Leveraging the technical strength of its provincial-level R&D center, Qinglong has established a dynamic mix ratio system tailored to different climate zones: ultra-fine mineral powder and silica fume are introduced into cement-based materials to replace 30%-40% of the cement content, effectively reducing hydration heat and shrinkage rate; alkali-resistant glass fibers 12-25mm in length are uniformly dispersed at a volume dosage of 2.5%-3.5%, forming a three-dimensional spatial network structure that raises the flexural strength of components to over 20MPa; through the combined use of specialized water reducers and water-retaining agents, the water-cement ratio is strictly controlled within the range of 0.35-0.45, ensuring a balance between slurry fluidity and water retention. Compared with traditional mix ratios, Qinglong's optimized GRC material achieves a 28-day drying shrinkage value as low as 0.03%, far exceeding the industry average.

Production Processes and Forming Techniques: Key Aspects of Refined Control

Advanced production processes are the guarantee for realizing material performance. At its production base in Nanning, Guangxi, Qinglong employs fully automatic spray forming equipment, using high-pressure air to uniformly mix fibers with mortar before they adhere to the mold surface, ensuring random fiber orientation and consistent embedment depth; for components with complex shapes such as double-curved surfaces and hollow-out designs, BIM technology is used for pre-assembly simulation to optimize demolding draft angles and rebar framework arrangements, avoiding stress concentration points; steam curing is initiated within 2 hours after pouring, maintaining a temperature of 60-80℃ and relative humidity ≥90% for 4-6 hours to accelerate cement hydration and stabilize the internal structure. In the Century Plaza renovation project on Nanjing East Road, the translucent GRC components produced by Qinglong using this process had dimensional errors controlled within ±2mm, with not a single case of setting-related cracking.

Curing System and Construction Coordination: Whole-Life-Cycle Crack Resistance Assurance

Scientific curing and construction coordination form the last line of defense against later-stage cracking. Qinglong has established a "three-stage curing method": in the initial curing stage (0-12 hours), film covering retains moisture and prevents the surface from losing water too quickly; in the middle curing stage (1-7 days), water spraying or wet burlap covering keeps the surface moist; in the final curing stage (7-28 days), natural curing is combined with monitoring of ambient temperature and humidity, with shading or insulation measures taken when temperature differences exceed 25℃. During on-site installation, 3D laser scanning positioning ensures that the connection joints between components and the main structure have a certain degree of flexibility, with 5-10mm expansion joints reserved to avoid additional stress caused by thermal deformation. In addition, Qinglong's after-sales maintenance service includes regular crack inspection and repair plans for GRC components, forming a closed-loop crack-resistant management system from production to operation and maintenance.

Preventing setting-related cracking in GRC components is essentially the systematic integration of material properties, process precision, and environmental control. As a national "Specialized, Refined, Distinctive, and Innovative" enterprise, Qinglong Group has always maintained an attitude of "meticulousness and the pursuit of excellence," transforming 28 years of engineering experience into replicable technical standards, and has participated in the formulation of multiple industry specifications, including the Technical Standard for Building Application of Glass Fiber Reinforced Cement (GRC). Going forward, Qinglong will continue to focus on the innovative R&D of UHPC/GRC/GRG/GRP materials, providing full-chain technical support for creating safer and more durable architectural decoration works, and joining hands with designers and owners to create "beautiful architecture."