1、Designation: D7227/D7227M 17Standard Practice forRapid Drying of Compacted Asphalt Mixture SpecimensUsing Vacuum Drying Apparatus1This standard is issued under the fixed designation D7227/D7227M; the number immediately following the designation indicates theyear of original adoption or, in the case
2、of revision, the year of last revision. A number in parentheses indicates the year of lastreapproval. A superscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers the process of drying compactedasphalt mixture specimens using vacuum dr
3、ying apparatus.1.2 The specimens dried by this practice remain at roomtemperature, which helps in maintaining specimen integrityduring the drying process.1.3 This practice can be used for compacted cylindrical andcubical laboratory and field asphalt mixture specimens.1.4 This practice can also be us
4、ed for drying other construc-tion materials such as concrete, soils, aggregates, and looseasphalt mixtures. Use the manufacturers recommendations fordrying other construction materials.1.5 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values s
5、tated ineach system may not be exact equivalent; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in nonconformancewith the standard.1.6 The text of this standard references notes and footnoteswhich provide explanatory material. These no
6、tes and footnotes(excluding those in tables and figures) shall not be consideredas requirements of the standard.1.7 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 saf
7、ety and health practices and determine the applica-bility of regulatory requirements prior to use.1.8 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International
8、Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D8 Terminology Relating to Materials for Roads and Pave-mentsD3666 Specification for Minimum Requirements for Agen-cies Testing and Insp
9、ecting Road and Paving MaterialsD5361 Practice for Sampling Compacted Bituminous Mix-tures for Laboratory Testing3. Terminology3.1 For definitions of terms used in this standard, refer toTerminology D8.4. Significance and Use4.1 Specimen dry weight is a critical measure in determi-nation of accurate
10、 density and many other tests in the construc-tion and raw materials industries. Drying specimens at roomtemperature is required for some tests and provides an advan-tage for other tests to ensure the integrity and to preserve thecharacteristics of specimens.4.2 This practice covers drying compacted
11、 asphalt mixturespecimens in a vacuum chamber that is capable of keeping thespecimen at close to room temperature. A vacuum pumpreduces the pressure inside the chamber, thus allowing water toevaporate at low temperature. Since the specimen naturallycools during the evaporation process, making water
12、harder toevaporate, it is important to have proper temperature controlsin the chamber to ensure the specimen remains at close to roomtemperature. Automatic controls within the unit allow thespecimen to remain at close to room temperature by periodi-cally allowing a flow of warm air to enter the vacu
13、um chamber.Cycling between vacuum and airflow conditions allows thespecimen to dry in a short period of time. Completely saturatedspecimens with over 30 g 0.07 lb of retained water can bedried in about 30 min. For most field cores that are notcompletely saturated, the drying time is generally less t
14、han15 min.1This practice is under the jurisdiction of ASTM Committee D04 on Road andPaving Materials and is the direct responsibility of Subcommittee D04.21 onSpecific Gravity and Density of Asphalt Mixtures.Current edition approved June 1, 2017. Published June 2017. Originallyapproved in 2006. Last
15、 previous edition approved in 2011 as D7227/D7227M 111. DOI: 10.1520/D7227_D7227M-17.2For 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
16、page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for
17、 theDevelopment of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.1NOTE 1Cycle time (period) can depend on the material composition.Each cycle involves an alternating period of 30 to 180 s of vacuumoperation and
18、30 to 120 s of air flow.4.3 This method can be used for 100 mm 4 in. diameter,150 mm 6 in. diameter cylindrical, and cubical compactedasphalt mixture specimens.4.4 This method can also be used for drying loose asphaltmixtures, aggregate samples, and other solid specimens. Fol-low the manufacturers r
19、ecommended procedures for dryingspecimens other than compacted asphalt mixture specimens.4.5 This method can be used to determine moisture contentand amount of water loss during drying by weighing thesample before and after the drying operations.NOTE 2The quality of the results produced by this stan
20、dard aredependent on the competence of the personnel performing the procedureand the capability, calibration, and maintenance of the equipment used.Agencies that meet the criteria of Specification D3666 are generallyconsidered capable of competent and objective testing, sampling,inspection, etc. Use
21、rs of this standard are cautioned that compliance withSpecification D3666 alone does not completely ensure reliable results.Reliable results depend on many factors; following the suggestions ofSpecification D3666 or some similar acceptable guideline provides ameans of evaluating and controlling some
22、 of those factors.5. Apparatus5.1 Absorptive Cloth or Paper Towels, for drying waterfrom surface of the specimens.5.2 Vacuum Chamber, with a pump capable of evacuating asealed and enclosed chamber to a pressure of 6 mm Hg6 Torr, when at sea level. The chamber shall be large enoughto accommodate spec
23、imens of 150 mm 6 in. width ordiameter and 180 mm 7 in. in height. The device shall havean automatic vacuum, airflow, and temperature control featuresto ensure proper drying of the specimen at close to roomtemperatures. Automatic controls of the unit shall be calibratedby the manufacturer prior to i
24、nitial use. The device shall havethe capability to display vacuum readings in the chamber andnumber of cycles.5.3 Water Removable Plate, used for removing free waterfrom the bottom surface of the specimen chamber.5.4 Electronic cold trap with an airflow divider plate, usedfor trapping water and stop
25、ping it from entering the vacuumpump.FIG. 1 Water Removal Plate and Sample Holder Installed in Sample ChamberD7227/D7227M 1725.5 A handheld infrared temperature sensor accurate to65 C 9 F for measuring surface temperature of the speci-mens.6. Sampling6.1 Test specimens may be molded from laboratory-
26、prepared specimens or taken from the pavement in the field.Field specimens should be obtained in accordance with Prac-tice D5361.7. Test Specimen7.1 To speed up the drying process, keep and maintain thespecimens to be dried between 15 C and 30 C 60 F and85 F.7.2 If desired, specimens may be separate
27、d from otherpavement layers in accordance with Practice D5361.8. Procedure8.1 Turn On the UnitPlug the unit in a power outlet andturn on the on/off switch. Follow the manufacturers recom-mendations for warm up and self test procedures.8.2 Daily TestEvery day before starting the testingoperation, dry
28、 the cold trap and the specimen chamber. Run theunit without any specimens. The pressure reading on thedisplay should be 6 mm Hg 6 Torr or less. If the indicatedpressure is higher than 6 mm Hg 6 Torr, check the system foritems that might need service, such as oil level and quality,seals, or water in
29、 the chamber. Refer to the manufacturerstroubleshooting instructions for obtaining a proper pressurereading in the chamber. For drying other constructionmaterials, follow the manufacturers recommendations forpressure requirements in the chamber.8.3 Drying SpecimensUse a handheld infrared thermom-ete
30、r to ensure that the surface temperature of the specimen isbetween 15 C and 30 C 60 F and 85 F. If the specimen isbelow 15 C 60 F or above 30 C 85 F, place the speci-mens in a room temperature environment until the surfacetemperature approaches the required testing temperature of15 C to 30 C 60 F an
31、d 85 F.8.3.1 Use paper towel or an absorptive cloth to remove anystanding water from the surface of the specimen.8.3.2 Place the specimen on top of the specimen supportplate inside the chamber.8.3.3 Place the lid on the vacuum chamber and press the liddown to ensure secure contact between the lid an
32、d the chamber.Press the appropriate key, for example the Start key, to beginthe drying process.8.3.4 When the specimen is dry, the unit will automaticallystop. The unit is calibrated at the factory to sense a “dryspecimen condition.” Dry specimen condition is determined atthe factory for the pressur
33、e at which no water remains in thechamber. During testing, the unit continuously reads thepressure inside the chamber and checks this pressure againstthe “dry specimen condition” pressure determined duringfactory calibration. Follow manufacturers procedure for cali-brating the device to dry specimen
34、 condition.NOTE 3Sample is considered dry when the measured weight aftervacuum drying process is 0.1% or less of 24-h oven drying at 50 C122 F.8.4 Electronic Cold TrapLiquid and ice, or both, willaccumulate in the cold trap as specimens are drying. Betweendrying specimens and for faster drying, it i
35、s best to remove thecold trap lid and the airflow divider plate and wipe out any freestanding water in the cold trap. Always place the divider backinto the cold trap before drying the next specimen.9. Report9.1 Report the following information:9.1.1 At the end of the drying process, report the endin
36、gpressure in mm Hg Torr, and total number of cycles displayedon the screen. This information may be used by the manufac-turer or the user for trouble shooting the device, if needed.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item
37、mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical commit
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39、ting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive,
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