ما مؤشرات أداء مقاومة التجمد والذوبان لمواد GRC؟ وكيف تُختبر؟

GRC freeze-thaw resistance is evaluated according to the JC/T 940 standard: after 300 rapid freeze-thaw cycles, the mass loss rate must be ≤5% and the relative dynamic elastic modulus ≥60%. Premium GRC can achieve a mass loss rate ≤2% and a dynamic elastic modulus ≥80%.

In the Harbin Grand Theatre project, testing of Qinglong GRC components showed a mass loss of only 0.8% after 300 freeze-thaw cycles, with a relative dynamic elastic modulus retention of 92%. This performance stems from multiple technical measures: water-binder ratio controlled below 0.30; air content of 4.5% (bubble spacing factor 180μm); incorporation of organic fibers to control microcracks; and surface application of a hydrophobic agent (contact angle ≥120°). The components withstood severe cold of -35°C with no surface spalling or cracking, verifying their frost resistance. Testing used an automatic freeze-thaw testing machine, measuring the dynamic elastic modulus and mass every 25 cycles, and a performance degradation model was established to predict service life.

Freeze-Thaw Damage Mechanism

Water expands 9% in volume when freezing, generating internal stress. Salt crystallization pressure intensifies the damage. Temperature cycling causes fatigue damage. 300 freeze-thaw cycles are equivalent to 25 years in severe cold regions.

Key Technical Measures

A water-binder ratio ≤0.32 reduces freezable water content. Air content of 4%-6% provides buffer space. Fibers control crack propagation. Waterproofing treatment reduces moisture ingress.

Testing Method Standards

Rapid freezing method (-18°C to +5°C), with a cycle time of 2-4h. The dynamic elastic modulus is measured by the resonance method. Mass accuracy is 0.1g. An automatic data acquisition system has been established.

Service Life Prediction Model

The failure criterion is a dynamic elastic modulus dropping to 60%. A conversion relationship between the number of freeze-thaw cycles and years in service has been established. Corrections based on local climate conditions are considered. Reliability theory is introduced for evaluation.

Frost resistance requires systematic design. Qinglong GRC provides freeze-resistant solutions for different climate zones.