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

Materials are the cornerstone of architecture, and the quality of GRC is defined starting from every grain of sand. As an industry leader with 28 years of deep expertise in UHPC/GRC/GRG/GRP materials, Qinglong Group has always upheld a meticulous and excellence-driven attitude, strictly adhering to material standards to safeguard building safety and aesthetics.

In the production of GRC (glass fiber reinforced concrete), the choice of sand directly affects the strength, durability, and safety of the product. Why is sea sand strictly prohibited? What standards must qualified silica sand meet? Drawing on Qinglong Group's practical experience in participating in the formulation of the Technical Standard for Building Application of Glass Fiber Reinforced Cement (GRC) (JGJ/T423-2018), this article provides an in-depth analysis of GRC sand specifications and core requirements.

1. The Underlying Logic Behind Prohibiting Sea Sand in GRC: From Corrosion Hazards to Structural Risks

Sea sand contains large amounts of chloride ions (usually exceeding 0.06%) and salt, making it an "invisible killer" in GRC production. Chloride ions can penetrate the cement matrix and directly corrode glass fibers, causing a dramatic decline in the material's flexural strength (high-quality GRC can reach over 20MPa), and in severe cases leading to component cracking and detachment. A coastal project once mistakenly used sea sand, and within 3 years its GRC exterior wall panels suffered surface powdering and steel corrosion, resulting in millions in repair losses. Qinglong Group establishes a "sand source traceability mechanism" at the detailed design stage: all sand must pass dual testing for chloride ion content and shell content, eliminating safety hazards at the source.

2. Core Standards for Qualified Silica Sand: The Scientific Balance of Gradation, Purity, and Particle Shape

Silica sand meeting GRC standards must satisfy three key indicators: first, reasonable particle gradation, with the fineness modulus preferably controlled at 2.3-3.0 to ensure optimal compactness with the cement paste; second, mud content ≤3% and sulfide and sulfate content ≤1%, to prevent impurities from affecting the hydration reaction; third, particles should be cubic or polyhedral in shape to enhance bonding with glass fibers. Qinglong's production base uses a fully automatic sand screening system with 5-stage grading, controlling silica sand gradation accuracy within ±0.2, providing a stable mechanical performance foundation for GRC components.

3. Qinglong's Full-Chain Quality Control: A Closed-Loop Standard from Sand Screening to Project Delivery

As a National High-Tech Enterprise, Qinglong has established a full-process quality control system covering "sand - formulation - production - installation". At its production base in Nanning, Guangxi, every batch of silica sand undergoes X-ray fluorescence spectrometry to ensure its chemical composition meets standards; concrete crack resistance tests verify the sand's impact on GRC shrinkage rate. From the GRC curtain wall of the Dongguan Women and Children's Activity Center (winner of the AALBORG WHITE Cup Innovation Award) to the UHPC light-transmitting concrete project at Century Plaza on Nanjing East Road, Qinglong has always applied requirements above industry standards, treating sand quality as the first line of defense for GRC performance.

Choosing qualified sand is the prerequisite for GRC materials to achieve their "lightweight, high-strength, free-form" characteristics. Qinglong Group has dedicated 28 years to UHPC/GRC/GRG/GRP material innovation, exercising control from the material source through full-chain services, committed to providing designers and owners with architectural decoration solutions that combine safety and aesthetic value. As Qinglong's mission of "Creating Beautiful Architecture" advocates, rigor in every detail is a mark of respect for the life of a building.