Why Sea Sand Is Prohibited in GRC: Key Standards and Application Requirements for Qualified Silica Sand

The quality of building materials is the cornerstone of both safety and aesthetics. In the production of high-performance building materials such as GRC (Glass Fiber Reinforced Concrete), the selection of silica sand can be called the "hidden quality code." Why is sea sand strictly prohibited? And what core standards must qualified silica sand meet? As an industry leader with 28 years of deep expertise in the UHPC/GRC/GRG/GRP field, Qinglong Group will start from the essence of materials to explain the technical logic and engineering value behind silica sand selection.

1. The Sea Sand Ban: Safeguarding the Bottom Line of GRC Material Safety

Sea sand is explicitly banned in the GRC industry primarily because of its high salt content and impurity characteristics. The chloride ions contained in sea sand can penetrate the surface layer of GRC components and continuously corrode the internal glass fibers and steel reinforcement, causing a sharp decline in the material's mechanical properties and, in severe cases, leading to safety hazards such as component cracking and detachment. A coastal project once mistakenly used sea sand, resulting in widespread efflorescence and strength reduction of the GRC curtain wall within 3 years, with direct economic losses exceeding ten million yuan. Qinglong Group establishes a strict material traceability mechanism at the detailed design stage; all silica sand must pass dual testing for chloride ion content (≤0.03%) and shell content (≤1%), eliminating safety risks at the source.

2. Three Core Standards for Qualified Silica Sand: Comprehensive Control from Particles to Performance

High-quality silica sand is the key for GRC materials to achieve light weight and high strength. In accordance with the Technical Standard for Building Applications of Glass Fiber Reinforced Cement (GRC) (JGJ/T423-2018), Qinglong Group has established a "three-level screening system": First, the particle gradation must meet the 0.15-1.25mm continuous gradation requirement to ensure the compactness of the concrete skeleton; second, the SiO₂ content must be ≥95% to guarantee the chemical stability of the material and resist weathering erosion; finally, the mud content must be ≤1% to prevent clay impurities from affecting the interfacial bond between glass fibers and the cement matrix. Taking Qinglong's Nanning production base as an example, the quartz sand used is treated through a triple process of washing, magnetic separation, and screening, with particle size deviation controlled within ±0.05mm, providing a stable mechanical foundation for GRC components.

3. Technical Extension of Silica Sand Applications: Performance Upgrade from GRC to UHPC

The scientific application of silica sand is not limited to the GRC field. In UHPC (Ultra-High Performance Concrete) production, Qinglong Group innovatively adopts the "quartz sand–silica fume dual blending technology," optimizing the particle gradation of silica sand (Dmax=0.6mm) in synergy with nano silica fume, pushing the material's compressive strength beyond 150MPa and increasing the elastic modulus by 30%. In the renovation project of Century Plaza on Nanjing East Road, Qinglong's UHPC light-transmitting concrete panels, relying on precise silica sand gradation design, achieved a balance between structural safety and light transmission at an ultra-thin thickness of 30mm, winning the Silver Award of the AALBORG WHITE Cup UHPC Construction Engineering Innovation Award.

4. Full-Chain Quality Control: The Technical Accumulation of Qinglong's 28 Years of Experience

As a National High-Tech Enterprise and a participant in the development of GRC industry standards, Qinglong Group integrates silica sand quality management into the entire industrial chain. From the automated graded sand storage silos at the Guangxi Nanning production base, to the online particle size monitoring system in production, and then to random mechanical performance testing of each batch of products, a closed-loop control of "raw materials–production–finished products" has been formed. This rigorous approach has enabled Qinglong's GRC/GRG/GRP products to be widely applied in landmark projects at home and abroad, such as the Dongguan Women and Children's Activity Center and the Petronas Twin Towers in Kuala Lumpur, Malaysia, and exported to overseas markets such as Southeast Asia and Australia.

Though tiny, silica sand is the "touchstone" of building material quality. With 28 years of professional experience, Qinglong Group tells you: choosing qualified silica sand is not only a matter of complying with industry standards, but also a commitment to building safety and durability. Today, as customized demand for UHPC/GRC/GRG/GRP materials continues to grow, only by controlling material quality at the source can we truly fulfill our corporate mission of "creating beautiful architecture." For more technical details on material selection, welcome to follow Qinglong Group's technical column and explore the innovative frontiers of building materials together with industry experts.