1、Designation: D7227/D7227M 111D7227/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
2、or, in the case 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 NOTEThis Practice was editorially corrected in September 2012.1. Scope1.1 This practice
3、 covers the process of drying compacted asphalt mixture specimens using vacuum drying apparatus.1.2 The specimens dried by this practice remain at room temperature, which helps in maintaining specimen integrity during thedrying process.1.3 This practice can be used for compacted cylindrical and cubi
4、cal bituminous laboratory and field specimens asphalt mixturespecimens.1.4 This practice can also be used for drying other construction materials such as concrete, soils, aggregates, and loose asphaltmixtures. Use manufacturers the manufacturers recommendations for drying other construction material
5、s.1.5 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in eachsystem may not be exact equivalent; therefore, each system shall be used independently of the other. Combining values from thetwo systems may result in non-conformanceno
6、nconformance with the standard.1.6 The text of this standard references notes and footnotes which provide explanatory material. These notes and footnotes(excluding those in tables and figures) shall not be considered as requirements of the standard.1.7 This standard does not purport to address all o
7、f the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatoryrequirements prior to use.1.8 This international standard was developed in accordance with in
8、ternationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:2D8 T
9、erminology Relating to Materials for Roads and PavementsD3666 Specification for Minimum Requirements for Agencies Testing and Inspecting Road and Paving MaterialsD5361 Practice for Sampling Compacted Bituminous Mixtures for Laboratory Testing3. Terminology3.1 For definitions of terms used in this st
10、andard, refer to Terminology D8.4. Significance and Use4.1 Specimen dry weight is a critical measure in determination of accurate density and many other tests in the construction andraw materials industries. Drying specimens at room temperature is required for some tests and provides an advantage fo
11、r other teststo ensure the integrity and to preserve the characteristics of specimens.1 This practice is under the jurisdiction of ASTM Committee D04 on Road and Paving Materials and is the direct responsibility of Subcommittee D04.21 on SpecificGravity and Density of BituminousAsphalt Mixtures.Curr
12、ent edition approved June 1, 2011June 1, 2017. Published July 2011June 2017. Originally approved in 2006. Last previous edition approved in 2011 asD7227/D7227M 111. DOI: 10.1520/D7227_D7227M-11.10.1520/D7227_D7227M-17.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactAST
13、M Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made
14、 to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyr
15、ight ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14.2 This practice covers drying compacted asphalt mixture specimens in a vacuum chamber that is capable of keeping thespecimen at close to room temperature.Avacuum pump reduces the pressure i
16、nside the chamber, thus allowing water to evaporateat low temperature. Since the specimen naturally cools during the evaporation process, making water harder to evaporate, it isimportant to have proper temperature controls in the chamber to ensure the specimen remains at close to room temperature.Au
17、tomatic controls within the unit allow the specimen to remain at close to room temperature by periodically allowing a flow ofwarm air to enter the vacuum chamber. Cycling between vacuum and airflow conditions allows the specimen to dry in a shortperiod of time. Completely saturated specimens with ov
18、er 30 g 0.07 lb of retained water can be dried in about 30 minutes.min.For most field cores that are not completely saturated, the drying time is generally less than 15 minutes. 15 min.NOTE 1Cycle time (period) can depend on the material composition. Each cycle involves an alternating period of 30 t
19、o 180 secondss of vacuumoperation and 30 to 120 secondss of air flow.4.3 This method can be used for 100 mm 4 in. diameter, 150 mm 6 in. diameter cylindrical, and cubical compactedbituminous asphalt mixture specimens.4.4 This method can also be used for drying loose asphalt mixtures, aggregate sampl
20、es, and other solid specimens. Followmanufacturers the manufacturers recommended procedures for drying specimens other than compacted bituminous asphaltmixture specimens.4.5 This method can be used to determine moisture content and amount of water loss during drying by weighing the samplebefore and
21、after the drying operations.NOTE 2The quality of the results produced by this standard are dependent on the competence of the personnel performing the procedure and thecapability, calibration, and maintenance of the equipment used. Agencies that meet the criteria of Specification D3666 are generally
22、 considered capableof competent and objective testing, sampling, inspection, etc. Users of this standard are cautioned that compliance with Specification D3666 alone doesnot completely ensure reliable results. Reliable results depend on many factors; following the suggestions of Specification D3666
23、or some similaracceptable guideline provides a means of evaluating and controlling some of those factors.FIG. 1 Water Removal Plate and Sample Holder Installed in Sample ChamberD7227/D7227M 1725. Apparatus5.1 Absorptive Cloth or Paper Towels, Absorptive cloth or paper towels, for drying water from s
24、urface of the specimens.5.2 Vacuum Chamber, with a pump capable of evacuating a sealed and enclosed chamber to a pressure of 6 mm Hg 6 Torr,6 Torr, when at sea level. The chamber shall be large enough to accommodate specimens of 150 mm 6 in. width or diameterand 180 mm 7 in. in height. The device sh
25、all have an automatic vacuum, airflow, and temperature control features to ensureproper drying of the specimen at close to room temperatures.Automatic controls of the unit shall be calibrated by the manufacturerprior to initial use. The device shall have the capability to display vacuum readings in
26、the chamber and number of cycles.5.3 Water Removable Plate, used for removing free water from the bottom surface of the specimen chamber.5.4 Electronic cold trap with an airflow divider plate, used for trapping water and stopping it from entering the vacuum pump.5.5 A handheld infrared temperature s
27、ensor accurate to 65C 9 F 65 C 9 F for measuring surface temperature of thespecimens.6. Sampling6.1 Test specimens may be molded from laboratory prepared laboratory-prepared specimens or taken from the pavement in thefield. Field specimens should be obtained in accordance with Practice D5361.7. Test
28、 Specimen7.1 To speed up the drying process, keep and maintain the specimens to be dried between 15 C and 30C 60F and85F.15 C and 30 C 60 F and 85 F.7.2 If desired, specimens may be separated from other pavement layers in accordance with Practice D5361.8. Procedure8.1 Turn On the Unit: UnitPlug the
29、unit in a power outlet and turn on the on/off switch. Follow manufacturers themanufacturers recommendations for warm up and self test procedures.8.2 Daily Test: Test EverydayEvery day before starting the testing operation, dry the cold trap and the specimen chamber. Runthe unit without any specimens
30、. The pressure reading on the display should be 6 mm Hg.Hg 6 Torr or less. If the indicatedpressure is higher than 6 mm.mm Hg 6 Torr, check the system for items that might need service, such as oil level and quality,seals, or water in the chamber. Refer to the manufacturers trouble shooting troubles
31、hooting instructions for obtaining a properpressure reading in the chamber. For drying other construction materials, follow the manufacturers recommendations for pressurerequirements in the chamber.8.3 Drying Specimens: SpecimensUse a handheld infrared thermometer to ensure that the surface temperat
32、ure of the specimenis between 15C15 C and 30C 60F30 C 60 F and 85F.85 F. If the specimen is below 15C 60F15 C 60 F or above30C 85F,30 C 85 F, place the specimens in a room temperature environment until the surface temperature approaches therequired testing temperature of 15C15 C to 30C 60F30 C 60 F
33、and 85F.85 F.8.3.1 Use paper towel or an absorptive cloth to remove any standing water from the surface of the specimen.8.3.2 Place the specimen on top of the specimen support plate inside the chamber.8.3.3 Place the lid on the vacuum chamber and press the lid down to ensure secure contact between t
34、he lid and the chamber.Press the appropriate key, for example the Start key, to begin the drying process.8.3.4 When the specimen is dry, the unit will automatically stop. The unit is calibrated at the factory to sense a “dry specimencondition”.condition.” Dry specimen condition is determined at the
35、factory for the pressure at which no water remains in thechamber. During testing, the unit continuously reads the pressure inside the chamber and checks this pressure against the “dryspecimen condition” pressure determined during factory calibration. Follow manufacturers procedure for calibrating th
36、e deviceto dry specimen condition.NOTE 3Sample is considered dry when the measured weight after vacuum drying process is 0.1% or less of 24-hour24-h oven drying at 50C 122F.50 C 122 F.8.4 Electronic Cold Trap: TrapLiquid and ice, or both, will accumulate in the cold trap as specimens are drying. Bet
37、weendrying specimens and for faster drying, it is best to remove the cold trap lid and the airflow divider plate and wipe out any freestanding water in the cold trap. Always place the divider back into the cold trap before drying the next specimen.9. Report9.1 Report the following information:9.1.1
38、At the end of the drying process, report the ending pressure in mm Hg Torr, and total number of cycles displayed onthe screen. This information may be used by the manufacturer or the user for trouble shooting the device, if needed.D7227/D7227M 173ASTM International takes no position respecting the v
39、alidity of any patent rights asserted in connection with any item 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 s
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41、arters. Your comments will receive careful consideration at a meeting 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 stand
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