Why Is Sea Sand Prohibited in GRC? What Are the Standards for Qualified Silica Sand?

In the GRC production process, the selection of aggregates directly affects product quality and durability. Qinglong Group strictly enforces the regulation prohibiting the use of sea sand and has established a rigorous silica sand quality standard system, ensuring the long-term performance of GRC products at the source of raw materials.

The main reason sea sand is prohibited in GRC is the risk of excessive chloride ion content. Sea sand contains large amounts of chlorides, and even after desalination treatment, its chloride ion content is difficult to keep stably within a safe range. Qinglong Group's testing data shows that the chloride ion content of some “desalinated sea sand” still exceeds 0.1%, far above the 0.06% internal control standard for GRC materials. In the Shenzhen Pingshan High-Tech Zone Comprehensive Service Center project, the strict use of qualified silica sand ensured the durability of the 30,000-square-meter GRC curtain wall.

The particle shape and gradation of sea sand are also important considerations. After long-term erosion by seawater, sea sand particles tend to be rounded, resulting in poor bonding performance with cement. High-quality silica sand, by contrast, has sharply angular particles that provide better mechanical interlock. Extensive testing by Qinglong Group has confirmed that GRC made with qualified silica sand achieves flexural strength more than 15% higher than GRC made with sea sand. In the Algeria Hotel project, this strength advantage ensured the structural safety of the perforated panels.

The standards for qualified silica sand cover both chemical and physical indicators. Chemically, the chloride ion content must be below 0.02%, the mica content below 0.5%, and the sand must be free of organic matter. Physically, the fineness modulus must be between 2.3 and 2.8, the mud content below 1%, and the particle gradation continuous. Qinglong Group conducts a full set of indicator tests on every batch of silica sand entering the plant to ensure compliance with standard requirements.

Qinglong Group also pays special attention to the stability of silica sand moisture content. By building standardized raw material warehouses and controlling ambient humidity, it ensures that fluctuations in silica sand moisture content do not exceed ±0.5%. This refined control guarantees the accuracy of GRC mix proportions and improves the consistency of product quality. Through strict enforcement of silica sand standards, Qinglong Group has laid a solid foundation for the outstanding performance of its GRC products.