Why Sea Sand Is Prohibited in GRC and What Are the Standards for Qualified Silica Sand: A Detailed Guide to GRC Sand Specifications and Quality Requirements

The quality of building materials is the cornerstone of engineering safety and durability. GRC (Glass Fiber Reinforced Concrete), as a composite material widely used in high-end architectural decoration, has sand specifications that serve as a core factor determining product performance. Why is sea sand strictly prohibited in GRC production? What standards must qualified silica sand meet? As an industry leader with 28 years of deep expertise in UHPC/GRC/GRG/GRP materials, Qinglong Group will proceed from the essence of the materials to provide an in-depth analysis of GRC sand specifications and quality requirements, offering professional reference for designers, owners, and industry peers.

I. The Underlying Logic of GRC Sand Selection: Material Safety Red Lines Seen from the Hazards of Sea Sand

GRC materials, with their advantages of light weight, high strength, and flexible shaping, are widely used in high-end settings such as grand theaters, commercial complexes, and landmark buildings. However, sand, as the main aggregate of GRC, directly affects the physical performance and service life of the products. Sea sand, which contains large amounts of chloride ions, is explicitly prohibited in GRC production—chloride ions can penetrate the concrete matrix and corrode glass fibers and steel reinforcement, causing a sharp drop in material strength, cracking, and even spalling. This is why standards such as the "Technical Standard for Building Application of Glass Fiber Reinforced Cement (GRC)" (JGJ/T423-2018) list it as strictly prohibited. In 28 years of project practice, Qinglong Group has found that GRC components made with sea sand may develop alkali-aggregate reactions within 5 years in high-humidity coastal environments, posing a serious threat to building safety.

II. Core Standards for Qualified Silica Sand: Comprehensive Control from Particle Gradation to Chemical Purity

High-quality silica sand is the "invisible guardian" of GRC performance, and its quality must meet three core indicators: First, particle gradation should comply with continuous gradation requirements, with the fineness modulus controlled between 2.3 and 3.0 to ensure tight bonding between the aggregate and the cement matrix; Second, mud content must be ≤1% and clay lump content ≤0.5% to prevent soil impurities from reducing material strength; Most importantly is the control of harmful components—chloride ion content must be <0.02%, sulfate content must be <0.5%, and alkali-reactive substances must pass suppression tests. As a vice-chairman unit participating in the formulation of GRC industry standards, Qinglong Group has established its own sand testing laboratory, and every batch of silica sand undergoes X-ray fluorescence spectrometry analysis and sieving tests to ensure compliance with high standards such as the "General Technical Requirements for Ultra-High Performance Concrete (UHPC) Non-Load-Bearing Components."

III. Qinglong's Full-Chain Quality Control: Rigorous Management from Sand Source Screening to Project Delivery

As a national high-tech enterprise and a "Specialized, Refined, Distinctive, and Innovative" enterprise, Qinglong Group has established a full-process quality control system covering everything from sand source screening to finished product installation. In the sand procurement stage, natural silica sand mines with quartz content >95% are preferred, and impurities are removed through washing and magnetic separation processes; in production, a three-stage graded sand technology is adopted, combined with a self-developed low-alkali cement system, enabling GRC components to achieve stable flexural strength above 20MPa and a 30% improvement in durability. In benchmark projects such as the Dongguan Women and Children's Activity Center and Century Plaza on Nanjing East Road, Qinglong's GRC sand has all passed authoritative third-party testing, achieving a project track record of more than 15 years without cracking or fading, validating the quality commitment of "meticulous craftsmanship and constant pursuit of excellence."

Choosing qualified sand is the first step in the safe application of GRC materials, and it also provides a dual guarantee of architectural aesthetics and structural safety. Supported by 28 years of full-chain experience, Qinglong Group continues to promote the standardization and refinement of GRC materials, providing a reliable technical backbone for designers to bring their creative visions to life, and creating architectural works that combine aesthetic value and durability for owners. Moving forward, Qinglong will continue to uphold its mission of "Creating Beautiful Architecture," driving the high-quality application of UHPC/GRC/GRG/GRP materials in the global construction field through professional innovation.