Bitumen emulsion is a mixture of fine droplets of bitumen and water. But as the bitumen is a petroleum product it doesn’t mix with water and as it is sticky in nature, it doesn’t easily gets disintegrated into fine droplets. To overcome this problem an emulsifier is used.
Emulsifier can be defined as a surface-active agent. Emulsifier keeps the bitumen in its fine droplet state by disallowing it to mix with other droplets. As the droplets are very fine they suspend in water.
“Therefore, bitumen emulsion is a dispersed liquid consisting of three products, i.e. water, bitumen and emulsion”.
Manufacture of Bitumen Emulsion
The production of bitumen emulsion takes place in two simple steps:
Step 1:
Firstly, the water is mixed with the appropriate emulsifier and other chemical agents. The choice of emulsifier depends upon its ionic nature of the mix.
Step 2:
Now water emulsifier mix is added with bitumen in a colloidal mill. The amount of bituminous to be added depends upon the nature of use of bitumen emulsion. If it is used for important works then between percent can range up to 60 to 70%.
The average range of bitumen mixed is from 40 to 70%.
The colloidal mill breaks down the bitumen into very tiny droplets. Average size of bitumen droplet is about 2 Micron. But the droplets try to join them self with each other and make it settle down.
But the emulsifier added creates a coating of surface charge around every drop droplet of the bitumen that helps to keep away from each other on the other hand it is also it also keeps the droplet in dispersed and suspended form.
The mix received from the colloidal mill is stored in the storage tanks and used as per requirement.