How to Prevent Cracking of GRC Components During Setting? — A Guide to Crack Control Technology and Process Optimization

Crack prevention during the setting process of GRC components is a core technology for ensuring component integrity, requiring systematic solutions through material optimization, process control, and structural design. Based on 28 years of experience in crack prevention, Qinglong Group holds that the crack width of high-quality GRC components should be controlled below 0.1mm, and that early cracking risk can be reduced to below 1% by adding polypropylene fibers, optimizing curing regimes, and improving expansion joint design.

Material modification enhances crack resistance. Adding polypropylene fibers (volume dosage 0.1%-0.2%) effectively suppresses plastic shrinkage cracks. In the production of hyperbolic panels for the Wuhan Hanxiu Theater, Qinglong Group improved the early crack resistance of components by more than 50% through fiber reinforcement. Optimizing the cementitious material system by adding active admixtures such as fly ash and slag powder reduces hydration heat and lowers the risk of temperature cracks. In mix proportion design, the drying shrinkage rate is controlled below 0.02%, reducing shrinkage stress at the source.

Curing technology is a key control link. A scientific curing regime should be established, including moisture-retention curing after initial setting and temperature-retention curing during the strength development period. In the Shenzhen Pingshan High-tech Zone Comprehensive Service Center project, Qinglong Group adopted an automatic sprinkler system to keep component surfaces moist for 7 days, ensuring uniform strength development. For mass components, the temperature difference between interior and exterior is controlled at ≤20℃ to avoid thermal stress cracks. Formwork removal time is determined according to strength development; formwork may only be removed once the compressive strength reaches above 10MPa to prevent early damage.

Structural design releases restraint stress. Expansion joints are properly arranged with spacing not exceeding 5m and joint widths of 10-15mm. Reinforcing bars are added at component corners to avoid stress concentration. Qinglong Group optimizes reinforcement schemes through finite element analysis, keeping cracks within a range that does not affect usability or appearance. These systematic measures ensure the integrity of GRC components.