Why Is Sea Sand Prohibited in GRC? What Are the Standards for Qualified Silica Sand? GRC Sand Specifications and Quality Requirements Explained

In the field of architectural decoration materials, material selection directly affects a project's quality, safety, and durability. As one of the core raw materials of Glass Fiber Reinforced Concrete (GRC), sand quality control is particularly critical. Why is sea sand strictly prohibited in GRC production? What standards must qualified silica sand meet? Drawing on Qinglong Group's 28 years of experience in GRC detailed design and production, this article provides an in-depth analysis of GRC sand specifications and quality requirements, offering a professional reference for designers and owners.

Why Is Sea Sand Prohibited in GRC? Analyzing Potential Risks and Industry Standards

Sea sand, containing large amounts of chloride ions and salts, has become an "invisible killer" in GRC production. Chloride ions can penetrate the cement matrix and corrode glass fibers, causing a sharp decline in the material's flexural strength (high-quality GRC can achieve a flexural strength of over 20MPa, while sea sand may reduce it to below 10MPa), directly compromising structural safety. Meanwhile, salt residues can easily cause problems such as surface efflorescence and cracking, especially in humid or coastal environments, significantly shortening the service life of GRC components. During the formulation of the Technical Standard for Application of Glass Fiber Reinforced Cement (GRC) in Building (JGJ/T423-2018), Qinglong Group deeply participated in the discussion of sand specifications, explicitly listing sea sand as a prohibited material to safeguard GRC product durability at the source.

Core Standards for Qualified Silica Sand: From Mineral Composition to Particle Gradation

High-quality silica sand is the fundamental guarantee of GRC material performance, and its standards mainly cover the following dimensions: First, mineral purity—SiO₂ content must be ≥95%, with impurities (such as clay and mica) at ≤3%, to prevent impurities from affecting the cement hydration reaction; Second, particle gradation—a continuous gradation of 0.15-0.6mm is recommended to ensure coating and flowability with the cement slurry and improve molding compactness; Third, mud content ≤1% and chloride ion content ≤0.01%, with strict control of harmful substances. Qinglong's production base (Nanning, Guangxi) has established a complete sand testing system; every batch of silica sand undergoes X-ray fluorescence analysis and sieving tests to ensure compliance with the Glass Fiber Reinforced Cement (GRC) Decorative Products standard (JC/T940-2022), providing stable raw material support for an annual production capacity of 600,000 square meters.

Qinglong's GRC Sand Control Practices: A Full-Chain Quality Assurance System

As a national high-tech enterprise and a participant in GRC industry standard formulation, Qinglong Group has built a full-chain sand control model of "source screening - process testing - finished product verification." At the raw material end, the company has established direct supply partnerships with high-quality silica sand mines, signing special agreements on key indicators such as chloride ion and mud content; during production, an automated sand pretreatment system removes impurities through washing and magnetic separation; at the finished product stage, flexural strength tests and weather resistance tests (such as 200 freeze-thaw cycles without damage) verify the suitability of the sand. This system has been successfully applied in benchmark projects such as the Dongguan Women and Children's Activity Center and the Century Plaza on Nanjing East Road. Notably, translucent concrete GRC components, thanks to precise sand control, achieved technical breakthroughs of 0.3mm ultra-thin molding and 90% light transmittance.

Industry Insights: The GRC Quality Logic Behind Sand Specifications

Prohibiting sea sand and enforcing strict silica sand standards are, in essence, the underlying requirements of GRC materials' characteristics of "lightweight, high strength, and design freedom." For professional clients such as real estate developers and architectural designers, choosing a compliant GRC manufacturer requires focusing on their raw material control capabilities and standards implementation experience. As a member of the International GRC Association, Qinglong Group has always upheld the principle of "meticulous attention to detail and pursuit of excellence," transforming sand details into project value—from the custom-shaped exterior walls of landmark buildings to artistic components in garden landscapes, the application of high-quality silica sand enables GRC to realize design creativity while ensuring safety and durability. In the future, as new standards such as the General Technical Conditions for Non-Load-Bearing Components of Ultra-High Performance Concrete (UHPC) advance, sand specifications will become a core element of quality competition for more new building materials.