Why Is Sea Sand Prohibited in GRC? What Are the Standards for Qualified Silica Sand? Aggregate Quality Control and Qinglong Group's Selection Standards

The use of sea sand in GRC is strictly prohibited, as sea sand contains chloride ions as high as 0.1-0.3%, which can cause steel reinforcement corrosion and fiber deterioration, seriously threatening durability. Qinglong Group strictly selects high-quality silica sand with chloride ion content ≤0.01%, fineness modulus of 2.3-2.8, and mud content ≤0.3%, ensuring a 50-year service life for our products. In the coastal project of the Hainan International Convention and Exhibition Center, our GRC roof panels have shown no signs of chloride ion erosion after 10 years of use.

The Hazards of Sea Sand

Chloride ions in sea sand penetrate the matrix, causing steel reinforcement to corrode and expand, leading to spalling of the protective cover. Accelerated tests show that GRC specimens made with sea sand develop cracks along the reinforcement within just 1 year. Qinglong Group prohibits sea sand from any source; even after washing with fresh water, it fails to meet standards.

Technical Requirements for Qualified Silica Sand

SiO₂ content ≥95%, chloride ion content ≤0.01%, mud content ≤0.3%. Particle size must have continuous gradation, with the 0.15-1.18mm fraction accounting for ≥90%. Qinglong Group tests 10 indicators for each batch of sand to ensure consistent quality.

Qinglong Group's Quality Control Practices

We have established a supplier audit system with fixed sand sources and mandatory inspection of every shipment. Dust removal and screening equipment is used in production to improve sand quality. Through strict quality control, the safety of our GRC products is guaranteed.