In evaluating the performance of equipment such as bituminous machines, it is necessary in all cases to take into account the quality of the emulsion obtained. The main indicator of quality is the dispersion of the emulsion, which is determined in practice using microscopic analysis. For these purposes, in addition to the microscope, you need to have a micrometer object and an eyepiece micrometer or eyepiece grid.
Take 3-4 drops of the prepared emulsion and dilute them in a large volume (about 100 cm3) of an aqueous solution of emulsifier, on which the emulsion was prepared. Droplets of diluted emulsion are placed in the slide of the slide and carefully place a cover glass on top so that there are no air bubbles between the two glasses.
Next, an eyepiece micrometer (or eyepiece grid) is inserted into the eyepiece and the sizes of the droplets of the binder in the emulsion are compared with graduations on the scale. All measured droplets are divided into classes: 0 – 1 micron, 1 – 2 microns, etc.
Then, using the data obtained in the rectangular coordinate system, distribution curves are constructed. The diameter of the droplets in microns is plotted on the abscissa axis, and the number of droplets or their volume content is plotted along the ordinate axis.
Dispersion of emulsions
In addition to the properties and the ratio of emulsifiable materials, the dispersion of emulsions is affected by: emulsification mode, working gap width, temperature of emulsification, etc.
Rotor speed of the bitumen machine
Affects the quality of the emulsion produced as follows. With a circumferential speed of 3 m / s, the bitumen emulsion is non-uniform, even with a very topical emulsifier. At a circumferential speed of 9 m / s, it is possible to emulsify on less active emulsifiers, but the emulsion also turns out to be non-uniform. Highly dispersed and homogeneous emulsion is obtained at a speed of more than 15 m / s.
The concentration of binder bitumen in the emulsion
A large influence on the performance of bitumen-emulsion machines has a concentration of binder (bitumen) in the emulsion. This effect is partly due to a change in the viscosity of the emulsion with a change in the amount of bitumen.
An increase in the bitumen content in the emulsion contributes to an increase in the dispersion and allows emulsification over a large gap width.