As an alternative to the use of a furnace to determine the amount of binder and aggregate content in an asphalt mixture there is now a machine available that uses solvent extraction to separate the binder and aggregate from the bitumen and uses distillation to recover the solvent.
This is a closed system extraction method for the determination of sieve analysis, binder content and if requested, binder quality.
The bitumen analysis process is achieved by:
• Solution of binder using a washing chamber and a rotating sieve drum
• Separating the filler and binder/solvent in a high performance centrifuge
• Attached distillation unit to separate binder and solvent
• Drying of minerals and filler and re-use of solvent
This fully automatic machine operates under a vacuum so there are no solvent fumes released to the laboratory. Further, the machine has a vent which can be connected externally or to an activated carbon filter etc. This machine also overcomes the problem of several existing types of machines where the aggregate and binder samples are fully dried and do not require any later drying in an oven which can cause problems with solvent escaping into the lab.
This machine operates at low temperatures so that the binder weight is not decreased in the same way as with a furnace. Recent developments have also included the use of non-toxic solvents and solvents which have appropriate specific gravity to allow powdered rubber to be separated from the other components in a bitumen mix that contains rubber. With new development and innovation, reduced solvent loss per extraction is achieved. The new Asphalt Analyser unit achieves less than 20ml of solvent loss per cycle.