Why Sea Sand Is Prohibited in GRC: Qualified Silica Sand Standards and Qinglong Raw Material Control System

Raw material selection is the fundamental guarantee of GRC material quality. Sea sand is strictly prohibited from use in GRC production due to its inherent characteristics, while qualified silica sand has become the core aggregate choice for premium GRC. Qinglong, a professional manufacturer with 28 years of full-chain GRC experience, has established a stringent raw material control system to ensure product quality from the source.

The core reason sea sand is prohibited in GRC lies in its high chloride ion content and impurity contamination. Sea sand contains large amounts of salts such as sodium chloride, with chloride ion content typically above 0.1%, far exceeding the 0.06% limit permitted for GRC materials. These chloride ions severely corrode alkali-resistant glass fibres, causing fibre strength degradation and accelerated ageing, and destroying the interfacial bond between fibres and the cement matrix, ultimately causing the flexural and tensile performance of GRC components to decline dramatically. At the same time, chloride ions can trigger corrosion of the steel frame inside GRC (if present), and the volume expansion caused by rusting leads to cracking and spalling of components, seriously compromising structural safety. In addition, impurities in sea sand such as shells and salts reduce the workability and compactness of the GRC mix, resulting in surface sanding and hollowing of products, affecting both decorative effect and durability. Through years of project practice, Qinglong has found that GRC components produced with sea sand develop problems such as strength loss and surface damage within 3-5 years, while products made with qualified silica sand can serve stably for more than 20 years.

Qualified silica sand must meet strict technical standards to serve as the ideal aggregate for GRC. According to industry specifications, qualified silica sand for GRC shall meet the following requirements: chloride ion content ≤0.01%, to ensure no corrosion problems arise; silicon dioxide content ≥95%, with high hardness and good wear resistance, to enhance GRC strength and durability; reasonable particle grading, with particle size between 0.15-1.25mm, of which particles of 0.3-0.6mm account for no less than 50%, ensuring good compactness with the cement paste; mud content ≤1% and clay lump content ≤0.5%, to prevent impurities from affecting mix performance; water absorption ≤2%, to reduce impact on the GRC water-cement ratio. The relevant industry standards that Qinglong participated in formulating clearly specify the various indicators for silica sand used in GRC, providing a scientific basis for raw material selection.

Qinglong has established a three-level silica sand control system of "source screening - warehousing inspection - process monitoring" to ensure that every batch of raw materials meets standards. In source screening, Qinglong has established long-term partnerships with premium silica sand mines, giving priority to natural silica sand with high quartz content and low impurities. In the warehousing inspection stage, each batch of silica sand is tested for multiple indicators including chloride ion content, mud content and particle grading, and raw materials that fail inspection are firmly rejected. During production, an automated aggregate metering system precisely controls the silica sand dosage, while mix performance is monitored in real time to ensure that silica sand works synergistically with other materials. In the Dongting Lake Museum GRC imitation-stone component project, the premium silica sand selected by Qinglong enabled the components to achieve a simulation fidelity of over 95% while ensuring high strength and durability. In the Singapore international project, strictly standard-compliant silica sand allowed GRC products to successfully adapt to the tropical marine environment. For owners and designers, whether raw materials are qualified directly determines the quality and lifespan of GRC products. Only by choosing a supplier like Qinglong with a comprehensive raw material control system can risks from unqualified materials such as sea sand be avoided at the source, ensuring the safety and stability of GRC architectural decoration.