Test method for roundness of road glass beads
The roundness rate of reflective glass beads for road use is defined by specifying certain test conditions and artificially dividing glass beads into round beads and non-circular beads, which can be specifically divided into the following two test methods.
1、 Test method of glass bead shape selector
1. Clean the glass plate and the glass bead collector of the glass bead selector by using a cotton ball dipped with a little industrial alcohol.
2. The glass bead shape selector is composed of glass plate, vibrator, regulator and bracket. The glass plate is 150 mm wide and 380 mm long, and its angle with the horizontal direction should be adjustable between 0-5 degrees. The vibration frequency of the glass plate is 50 Hz, and the vertical amplitude of the glass plate can be changed from 0 to 0.5 mm by the regulator.
3. Weigh about 20g sample from the glass bead pattern, accurate to 0.1g.
4. Turn on the power switch of the glass bead selector, adjust the slope of the glass plate and the amplitude of the vibrator, so that the defective glass beads on the glass plate slowly move upward, while the truly round glass beads roll downward.
5. Use a small spoon to feed the glass plate of the shape selector slowly, so that the glass beads will not accumulate ｏｒ slide on the glass plate. All the beads will roll into the ball collector, and the defective glass beads will slowly enter the non-circular bead collector until all glass bead samples are separated.
6. Separate the collected round glass beads and defective glass beads through the glass bead shape selector until all the round glass beads are separated; and after all the defective glass beads pass through the shape selector, no round glass beads are separated.
7. Weigh the total mass n (g) of all the separated round glass beads and the total mass C (g) of the defective glass beads to the accuracy of 0.1g. The roundness rate of glass beads is p = n / (n + C).
2、 Microscope test method
The adhesive tape with glass beads is bonded to the glass carrier plate, and the carrier plate is placed in the field of view of the microscope. The area containing about 200 glass beads is constructed with a grid of appropriate size. After that, photos are taken. According to the figures of "round" and "non-circular" glass beads, round and non-circular beads are distinguished, and then the roundness rate of glass beads is calculated.