It is natural by-product of distillation of crude petroleum. In fact it is a substance containing high
percentage of bitumen and some inert mineral substances. Actually bitumen is the basic constituent of asphalt.
Thus the main difference between bitumen and asphalt is as follows:
When crude petroleum is fractionally distilled in refineries the product is called “bitumen” while the
natural distilled product is known as asphalt. It is blackish-brown is colour, non- inflammable, but burns with a
smoky flame at 250°C temperature.
According to the source, asphalt can be defined as:
(a) Natural or lake asphalt (b) Rock asphalt
(a) Lake asphalt. It is a natural asphalt, found in lakes; It contains about 40 to 70% bitumen and about
30% water, lime, clay and sand etc. lake asphalt is refined by boiling it in tanks. In this process the
water evaporates, and the impurities float to the surface and are removed. It is the best material for
(b) Rock asphalt The asphalt occurring within porous rock structure such as sand stone or lime stone is
known as rock asphalt and quarried and refined. It contains abut 20% bitumen and rest stone.
Asphalt plant in operation
compaction of road