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

In the field of architectural decoration materials, GRC (glass fiber reinforced concrete) has become an ideal choice for high-end buildings such as grand theaters and commercial complexes, thanks to its lightweight, high strength, and rich design versatility. However, the selection of raw materials directly determines the quality and safety of GRC products, among which the choice of sand is particularly critical. As a group with 28 years of full-chain experience in UHPC/GRC/GRG/GRP materials, Qinglong Group today provides an in-depth analysis: why is sea sand strictly prohibited in GRC production? And what standards must qualified silica sand meet?

### 1. GRC Prohibits Sea Sand: Eliminating Building Safety Hazards at the Source

Sea sand is explicitly prohibited in GRC production due to its high chloride ion content. Chloride ions can penetrate the concrete protective layer and corrode the internal steel reinforcement and glass fibers, leading to reduced component strength, cracking, and even spalling. A coastal project that mistakenly used sea sand saw its GRC exterior wall panels develop surface powdering and steel reinforcement corrosion within just 3 years, with later repair costs reaching as high as 40% of the original construction cost. Qinglong Group strictly implements a "triple sand testing" system in production, precisely detecting chloride ion content with X-ray fluorescence spectrometers to eliminate sea sand hazards at the source. This is also the core reason why Qinglong GRC products can be applied stably in overseas high-salt-spray environment projects such as Malaysia and Saudi Arabia. For more industry information: +WeChat qlfsbl123

### 2. Core Standards for Qualified Silica Sand: Laying the Cornerstone of GRC Quality

High-quality silica sand is key to ensuring GRC strength and durability. According to the "Technical Standard for Building Applications of Glass Fiber Reinforced Cement (GRC)" (JGJ/T423-2018), qualified silica sand must meet three core indicators: first, silicon dioxide content ≥95% to ensure the chemical stability of the material; second, reasonable particle gradation with the fineness modulus controlled between 2.3-3.0 to optimize concrete flowability and compactness; third, mud content ≤1% to prevent clay impurities from affecting interface bonding performance. Qinglong Group has established dedicated sand silos at its production base in Nanning, Guangxi, using automated screening systems to control sand precision. Its UHPC/GRC products achieve flexural strength of over 20MPa, far exceeding the industry average.

### 3. Full-Chain Quality Control: Qinglong's GRC Quality Assurance System

As a national high-tech enterprise, Qinglong Group incorporates raw material management into its full-process quality control system. From direct procurement at silica sand mines to incoming factory inspection and then mix ratio optimization, every step has digital records for traceability. For example, in the Nanjing East Road Century Plaza renovation project, the Qinglong team used BIM technology to simulate the impact of sand gradation on the optical performance of light-transmitting UHPC components, ultimately achieving a hyperbolic curved form with a minimum curvature radius of 300mm. The project won the Silver Award of the first AALBORG WHITE Cup UHPC Construction Engineering Innovation Award. This refined management "from sand to finished product" is an important reason why Qinglong has become a strategic partner of renowned real estate groups such as Poly and Vanke.

### 4. Industry Selection Advice: How to Identify High-Quality GRC Sand

For designers and owners, when selecting a GRC supplier, special attention should be paid to sand testing reports and production processes. It is recommended to prioritize manufacturers with self-built sand storage facilities and complete testing equipment, such as Qinglong Group, which participated in developing the industry standard "General Technical Conditions for Non-Load-Bearing Components of Ultra-High Performance Concrete (UHPC)". Meanwhile, sand quality can be intuitively judged by observing the compactness of GRC sample cross-sections and asking about freeze-thaw cycle resistance (Qinglong products can withstand over 300 cycles). Remember: qualified silica sand is the fundamental guarantee for GRC products to be safely used for more than 50 years. For more industry information: +WeChat qlfsbl123

From prohibiting sea sand to carefully selecting silica sand, the details reveal the quality code of GRC materials. Qinglong Group has always upheld the mission of "creating beautiful architecture", providing safe and reliable UHPC/GRC/GRG/GRP solutions for global projects with 28 years of professional experience. Only by choosing the right raw materials can architectural beauty endure and remain fresh over time.