As a matter of fact Bitumen is one of the most fascinating materials we have ever come across. And one of the most underestimated ones at the same time which again is part of its fascination.
What is actually known about bitumen is in fact very little:
Interestingly enough nobody knows exactly what Bitumen is. Accordingly all definitions you can find are descriptive rather than explaining what Bitumen is.
Generally speaking bitumen is a very complex mixture of more than 100,000 different hydrocarbons. It is commonly described as a colloidal system out of a continuous phase, the maltenes, and a dispersed phase, the asphaltenes.
After that early stage of the description there is already some disagreement amongst chemists regarding its structure and the composition of bitumen. It is stated that it is exceedingly difficult to separate individual hydrocarbons in pure form and that it is almost impossible to separate and identify all the different molecules of bitumen as the number of molecules with different chemical structure is extremely large.
So let us take a step back to the maltenes and asphaltenes. In an attempt to further describe the bitumen elemental composition the so called SARA analysis has been used which is originally an analysis method that divides crude oil components according to their polarizability and polarity. SARA stands for the four substance groups Saturates, Aromatics, Resins and Asphaltenes, whereby the Saturates, Aromatics and Resins together represent the maltene fraction.
As part of the work on bitumen chemistry and structure realised in the USA known as a the Strategic Highway Research Program, SHRP, which is a 20 year research program started 1987, the ASTM D4124 (standard test method for separation of bitumen into four fractions) had been developed in order to provide a standardised testing method. This method reflects the SARA composition of a bitumen.
It is undisputed that bitumen consists out of four substance groups, saturates, aromatics, resins and asphaltenes and that the balance of these four substances determine the quality of the bitumen. Furthermore the elements carbon, hydrogen, nitrogen, sulphur, oxygen, vanadium and nickel can be found.
Interestingly enough the term bitumen itself is as ambiguous as the composition of the material. For instance are the terms bitumen and asphalt used interchangeably to mean both natural and manufactured forms of the product. Outside the United States, the product is mainly called bitumen. Furthermore crude oils with an API gravity of less than 10 are referred to as bitumen as well, although we are still talking about an unrefined crude oil.
In essence it is fair to say that bitumen is not bitumen and from our point of view it is fundamentally insufficient to describe the quality of the construction material bitumen for instance by softening point and ring and ball values only. You need to go deeper than this. We are more than happy to support you by telling you how.