Production Process and Standards for Reflective Glass Beads Used in Road Markings

　　Road reflective glass beads are tiny spherical glass beads formed by melting glass sand (waste glass) at high temperatures. Under a microscope, they appear spherical, colorless, and transparent, with a refractive index ranging from 1.50 to 1.64 and diameters typically between 75 micrometers and 1,400 micrometers. Hence, they are also referred to as reflective glass microbeads. Currently, the two main production processes for road reflective glass beads in China are the flame floating method and the electric heating melting method.

　　Road reflective glass beads, used as reflective materials in road markings (paint), can enhance the retroreflective performance of pavement marking coatings and improve nighttime driving safety. This has been recognized by transportation authorities worldwide. When a vehicle drives at night, headlights shining on road markings equipped with glass beads cause the light to be reflected back parallel to its original path, enabling drivers to clearly see the direction ahead and thus significantly enhancing nighttime driving safety. Today, reflective glass beads have become an indispensable reflective material in road safety products.

　　Road-reflective glass beads are primarily used in both cold-applied and thermoplastic road marking paints. One type is added as a pre-mixed material, ensuring long-term reflectivity of the markings throughout their service life; the other type is sprinkled onto the surface during marking application, providing immediate reflective effects.

　　Coated glass microspheres come in two types: one is used for road reflectivity, and the other for screen reflectivity. These coated glass microspheres are externally treated with a high-performance organic material, which reduces the tendency of dust particles in the air to adhere to their surfaces. Thanks to the specific coupling agents contained within the coated microspheres, the adhesion between the microspheres and the coating is significantly improved, preventing some of the finer glass microspheres from settling into the coating. Due to their buoyant properties, these coated microspheres float on the surface of the coating during application, providing a large surface area that can increase utilization efficiency by more than 30%. After being coated, the glass microspheres exhibit even superior performance. In environments that are frequently rainy, foggy, or humid, they offer enhanced reflectivity.

　　Technical Parameters

　　Appearance: Colorless and transparent sphere, smooth and perfectly round, with no visible bubbles or impurities.

　　Roundness rate: Roundness rate ≥ 80% Density: 2.4–2.6 g/cm³ Refractive index: Nd ≥ 1.50

　　Composition: Sodium-calcium glass composition, SiO2 content > 70%

　　Standards implemented by some countries:

　　Chinese Standard GB/T 24722--2009

　　British Standard BS6088 Class A B;

　　American Standard AASHTO M247 Type 1, Type 2;

　　European standards EN1423 and EN1424;

　　Turkish Standard TS EN1423;

　　New Zealand Standard NZS2009: 2002;

　　Taiwanese Standard CNS;

　　Japanese Standard JIS R3301;

　　Australian Standard A, B, C, D.