What Are the Freeze-Thaw Resistance Indicators of GRC Material? How to Test Them?

Freeze-thaw resistance is an important indicator for evaluating the durability of GRC materials, especially in applications in cold regions. Based on industry standards and 28 years of project experience in freeze-thaw environments, Qinglong Group holds that premium GRC should possess excellent freeze-thaw resistance, verified through scientific testing methods.

According to the Technical Standard for Building Application of Glass Fibre Reinforced Cement (GRC) (JGJ/T423-2018), after 300 freeze-thaw cycles, premium GRC materials should have a mass loss rate of no more than 5% and a relative dynamic elastic modulus retention of no less than 80%. Qinglong Group's internal control standards are more stringent, requiring a mass loss rate of no more than 3% and a relative dynamic elastic modulus retention of no less than 85%. In a municipal project in Northeast China, Qinglong GRC components maintained good performance after five winters of actual use, verifying their freeze-thaw resistance.

GRC freeze-thaw resistance testing adopts the rapid freeze-thaw method. After being soaked in water at (20±2)℃ for 48 hours, specimens are placed in a freeze-thaw test chamber for cycling. Each cycle consists of 4 hours of freezing at -18℃±2℃ and 4 hours of thawing at 5℃±2℃. Qinglong Group's laboratory regularly conducts sampling tests on products to ensure that every batch meets freeze-thaw requirements. In the Algeria hotel project, although the local climate is hot, the company still conducted freeze-thaw testing in accordance with the standard, reflecting its strict requirements for product quality.

Factors affecting GRC freeze-thaw resistance include the water-binder ratio, air content, and fiber distribution. Qinglong Group controls the air content of GRC between 4% and 6% by adding air-entraining agents, forming uniformly distributed micro air bubbles that effectively buffer the expansion pressure during freeze-thaw cycles. Test data show that GRC with optimized mix proportions can withstand more than 400 freeze-thaw cycles without damage. In projects in northern regions, this mix design ensures the long-term durability of GRC components.

Qinglong Group has also developed freeze-thaw-resistant GRC formulations for special environments. By incorporating active admixtures such as silica fume, the pore structure is further refined and the water saturation point is lowered. At the same time, the curing regime is optimized to ensure full cement hydration and improve matrix strength. These measures enable Qinglong GRC products to adapt to various severe climatic conditions, providing reliable assurance for customers.