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

How to Prevent Cracking of GRC Components During Setting: A Discussion of Key Technologies and Practical Measures

In the field of architectural decoration, GRC (Glass Fiber Reinforced Concrete) is widely used in high-end projects such as grand theaters, commercial complexes, and landmark buildings thanks to its lightweight, high-strength, and flexible styling characteristics. However, GRC components are prone to cracking during the setting process, which not only affects aesthetics and structural safety but may also lead to increased project costs and construction delays. As an industry leader with 28 years of full-chain experience in UHPC/GRC/GRG/GRP materials, Qinglong Group has drawn on its deepened design, manufacturing, and installation practices to develop a systematic cracking prevention solution, providing professional technical support for designers and owners.

Analysis of the Core Causes of Cracking in GRC Components During Setting

The cracking of GRC components mainly stems from the combined failure of material mix proportions, forming processes, and curing environments. From the perspective of material properties, if the shrinkage stress generated by the hydration reaction of cement-based materials becomes unbalanced with the restraining effect of glass fibers, micro-cracks are likely to occur; during production, uneven fiber dispersion or improper water-cement ratio control can cause internal stress concentration within components; while temperature and humidity fluctuations during the curing stage may intensify the shrinkage difference between the surface and the interior. Taking a commercial complex project as an example, an unoptimized mix design once caused through cracks in cornice line components; later, by adjusting the silica fume content and fiber length distribution, the cracking rate was successfully reduced by 80%.

Prevention Technologies at the Material Science Level: Mix Optimization and Fiber Reinforcement

In material formulation design, Qinglong Group adopts a “dual admixture technology” to enhance the crack resistance of GRC: 10%-15% silica fume is added as a partial replacement for cement to reduce hydration heat and shrinkage; meanwhile, alkali-resistant glass fibers 12-25mm in length are selected to ensure a volume content of 3%-5%, forming a three-dimensional randomly oriented support structure. The optimal mix proportion obtained through orthogonal tests increases the flexural strength of GRC to above 20MPa and improves the elastic modulus by 15%, effectively suppressing early plastic cracking. In addition, adding 0.05%-0.1% polypropylene fiber as a toughening component can further alleviate drying shrinkage stress.

Production Process Innovation: Precise Control of Compression Molding and Steam Curing

In the manufacturing stage, Qinglong has introduced automated compression molding equipment, using pressure of 2.5-3.5MPa to increase the compactness of the mixture by 25% and reduce internal porosity. For large components (such as Roman columns taller than 3 meters), a “layered pouring + gradient pressurization” process is adopted to avoid settlement cracks caused by self-weight. Three-stage temperature control is implemented during the curing stage: during the initial setting period (0-4 hours), humidity is kept at ≥90% and temperature at 20-25℃; during the curing period (4-24 hours), steam curing at 60-70℃ is applied to accelerate strength development; during the cooling period, the components are cooled slowly at a rate of ≤5℃/h to prevent thermal stress cracking. Through this process, a museum project raised the first-pass acceptance rate of special-shaped curtain wall panels from 78% to 95%.

Coordinated Safeguards in Installation and Later Maintenance

Refined operations during on-site installation are equally critical for crack prevention. Qinglong uses BIM technology for pre-assembly simulation to accurately locate anchoring points and ensure uniform load distribution across components; installation gaps of 8-12mm are reserved and filled with elastic sealant to absorb thermal deformation. For projects in regions with large temperature differences, an innovative “sliding support” design has been developed, allowing components to expand and contract freely within a range of ±30mm. In terms of later maintenance, a regular inspection system has been established, and micro-cracks are sealed with a special repair mortar (mix ratio: cement:quartz sand:epoxy resin = 1:2:0.3) to prevent moisture ingress that could lead to corrosion of the steel reinforcement.

As a National High-Tech Enterprise and a participant in formulating GRC industry standards, Qinglong Group has always regarded technological innovation as its core competitiveness. From material R&D to engineering practice, through full-chain quality control, the company has successfully provided anti-cracking solutions for more than a thousand projects at home and abroad, among which the Dongguan Women and Children's Activity Center project won the Silver Award of the first GRC Construction Engineering Innovation Award. Moving forward, Qinglong will continue to deepen its expertise in the field of UHPC/GRC/GRG/GRP materials, guided by the mission of “creating beautiful architecture”, to provide more reliable technical support for designers in realizing their creative visions and to advance the industry toward high-quality development.