AASHTO R 59:2011 Standard Practice for Recovery of Asphalt Binder from Solution by Abson Method.
3.1. The solution of solvent and asphalt binder from a prior extraction is distilled under prescribed conditions to a point where most of the solvent has been distilled, at which time carbon dioxide gas is introduced into the distillation process to remove all traces of the extraction solvent. The recovered asphalt binder (distillation residue) can then be subjected to further testing as required.
4.1. The asphalt binder should be extracted from the asphalt mixture in accordance with Method A or E (Note 2) of T 164 as there is some experimental evidence that the recovered asphalt binder may have slightly lower penetration values when recovered from solutions obtained from hot extraction methods.
Note 2 —Equipment in Method E of T 164 can be modified by a vacuum trap attached to the top of the bendpoint site tube to collect the extract.
5.1. Centrifuge—Batch unit capable of exerting a minimum centrifugal force of 770 times gravity or a continuous unit capable of exerting a minimum fbrce of 3000 times gravity.
8.1. The sample shall consist of a solution, from previous extraction by Method A or E (Note 2) of T 164, of an asphalt mixture sample of sufficient mass to result in about 75 to 100 g of recovered asphalt binder. More or less quantities of asphalt binder may be recovered; however, the properties of the recovered asphalt binder may not be in agreement with those recovered from a sample of sufficient mass to result in an asphalt binder quantity of 75 to 100g. In case of a dispute, 75 to100 g should be recovered.
8.2. During the extraction process, it is important that all of the asphalt binder in the mixture be extracted as there could be some selective solvency of the asphalt binder. The harder, more viscous components of the asphalt binder might be left in the mixture if the extraction is not carried to completion.
8.3. Since heavy petroleum distillates such as mineral spirits or kerosene will affect the properties of the recovered asphalt binder, it is important to avoid the use of such solvents in cleaning the extraction and recovery apparatus and use only trichloroethylene or methylene chloride for cleaning. Residues of heavy petroleum solvents on the equipment may contaminate the recovered asphalt binder and affect its test properties, It is also necessary to use new filter rings, clean felt pads, or other uncontaminated filtering media in the extraction OCCSS to avoid contamination from a previous extraction.AASHTO R 59 pdf download.