ASTM_D_7906_-_14.pdf

Designation:D790614Standard Practice forRecovery of Asphalt from Solution Using Toluene and theRotary Evaporator1This standard is issued under the fixed designation D7906;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice is intended to be used to recover asphaltfrom a solvent using the rotary evaporator to ensure thatchanges in the asphalt properties during the recovery processare minimized.1.2 UnitsThe values stated in SI units are to be regardedas standard.No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D92 Test Method for Flash and Fire Points by ClevelandOpen Cup TesterD2172/D2172M Test Methods for Quantitative Extraction ofBitumen From Bituminous Paving MixturesD3666 Specification for Minimum Requirements for Agen-cies Testing and Inspecting Road and Paving Materials3.Summary of Practice3.1 The solution of solvent and asphalt from a prior extrac-tion is first distilled by partially immersing the rotatingdistillation flask of the rotary evaporator in a heated oil bathwhile the solution is subjected to a partial vacuum.During thefinal stage of the process,vacuum is increased and nitrogen orcarbon dioxide gas is introduced to the solution to removeremaining toluene and prevent further aging of the asphalt.Therecovered asphalt can then be tested as required.4.Significance and Use4.1 To determine the characteristics of the asphalt in anasphalt paving mixture,it is necessary to extract the asphaltfrom the aggregate by means of a suitable solvent and then torecover the asphalt from the solvent without significantlychanging the asphalts properties.The asphalt recovered fromthe solvent by this practice can be tested using the samemethods as for the original asphalt cement,and comparisonsbetween the properties of the original and recovered asphaltcan be made.4.2 Users are cautioned that the recovered binder propertiesfrom an asphalt mixture sample may not exactly represent theproperties of the original asphalt binder due to factors outsideof laboratory control such as aging,contamination,and mo-lecular changes caused by exposure to heat and solvents.Consequently,recovered asphalt binder properties should notbe used as a basis for acceptance.NOTE1The quality of the results produced by this is dependent on thecompetence of the personnel performing the procedure and the capability,calibration,and maintenance of the equipment used.Agencies that meetthe criteria of Specification D3666 are generally considered capable ofcompetent and objective testing,sampling,inspection,and so forth.Usersof this practice are cautioned that compliance with Specification D3666alone does not completely assure reliable results.Reliable results dependon many factors;following the suggestions of Specification D3666 orsome similar acceptable guideline provides a means of evaluating andcontrolling some of those factors.5.Apparatus5.1 Rotary Evaporator(see Fig.1),equipped with distilla-tion flask,variable speed motor capable of rotating the distil-lation flask at a rate of at least 40 rpm,condenser(Note 2),solvent recovery flask,and heated oil bath.The angle of thedistillation flask from the horizontal to the bath is set atapproximately 30 6 10.The distillation flask when fullyimmersed in the oil bath should be at a depth of approximately40 mm.5.2 Distillation and Receiving Flasks,a distillation flaskwith a minimum capacity of 1 L is required for the sufficientrecovery of asphalt binder.It is recommended for the receivingflask to have a minimum capacity of 1-L to maximize theamount of solvent recovery.1This practice is under the jurisdiction of ASTM Committee D04 on Road andPaving Materials and is the direct responsibility of Subcommittee D04.25 onAnalysis of Bituminous Mixtures.Current edition approved Jan.1,2014.Published February 2014.DOI:10.1520/D7906-14.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 NOTE2Avertical condenser is recommended for solvents with higherboiling points such as toluene.5.3 Vacuum Pump and Controller,capable of maintaining avacuum of 72.0 6 0.7 kPa down to 6.7 6 0.7 kPa.5.3.1 Vacuum Controller,built into rotary evaporator systemcont