The spread quantity of reflective glass beads in the construction of marking line should be moderate. If the amount of glass beads is too small, the reflection spots are little, and the brightness of marking line is poor. If the amount of glass beads is too much, it will be difficult to form a return reflection.
In the construction of road marking, if the surface spreading reflective glass beads are too many, it is easy to form "virtual bead". In this case, reflective glass beads can't attach well on the marking line, so it's easy to fall off from the marking surface. Before the "virtual bead" falls off, the light reflecting brightness of the marking at night is extremely poor, and the marking will have overall or partial darkening phenomenon.
When it comes to the embedded degree of glass bead, foreign research results show that: reflective glass beads embedded in the part of the marking is 55%~67% of the spherical diameter of the glass beads, at this time the light can almost completely reflect. For a single glass bead, when the embedding degree of the glass bead is less than 50%, the regression reflection effect can be extremely poor. When the embedding degree of glass bead is about 60%, the regression reflection effect is the best. As the degree of embedding increases, the regression effect decreases, because the amount of light entering the bead decreases with the degree of embedding. In actual construction, the distribution of glass beads is rarely single, but from the perspective of statistics, the optical behavior of many glass beads and the behavior of single glass beads are very similar under the above conditions.
In terms of geometrical dimensions of glass beads, in the use of marking, the glass beads with large particle size are easier to fall off from the marking surface than the glass beads with small particle size. This is because the torque of glass beads with large particle size are usually larger when they are stressed. However, the use of large particle glass beads can significantly improve the visibility of marking at night. In fact, the improvement of the return reflection effect of large particle glass beads is mainly reflected in the rainy night or wet road. Generally speaking, large particle glass beads and small particle glass beads are more effective in the wet and rainy night.
Glass beads - coating interface condition, interface properties and other factors also affect the regression reflection. In this case, glass beads - the coating interface is relatively smooth, close to the ideal concave mirror, which has a focusing effect on the light. The light entering the glass beads almost returns to the driver's vision along the original direction.
The coating itself is relatively rough, the coating is not too dense after film formation, and there are many bubbles or other fillers with larger particles in it. Glass beads - coating interface is acerbity, part with glass beads - air interface. Glass beads and coating interface becomes smaller, in this case, the light will not only scatter greatly, but also make part of the light escape through the glass bead - air interface. Whether scattering or light lines passing through the glass bead air interface, it will cause part of the light loss and reduce the return reflection effect. This is the reason that the reflectance of conventional hot-melt road marking coating is not as bright as MMA two-component road marking coating.