1、Designation: D7870/D7870M 13Standard Practice forMoisture Conditioning Compacted Asphalt MixtureSpecimens by Using Hydrostatic Pore Pressure1This standard is issued under the fixed designation D7870/D7870M; the number immediately following the designation indicates theyear of original adoption or, i
2、n 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. Scope1.1 This practice includes procedures for preparing com-pacted asphalt mixture specime
3、ns, exposing the specimens tohydrostatic pore pressure inside an enclosed chamber andguidance on testing the specimens for the effect of water on thetensile strength or change in other properties of the asphaltmixture, such as density, modulus, etc.1.2 Specimens conditioned according to this practic
4、e can betested using methods and test procedures referenced in thisdocument and those results may provide information as to theeffect of the moisture conditioning of this practice on themoisture sensitivity of those mixtures.1.3 The text of this standard references notes and footnoteswhich provide e
5、xplanatory material. These notes and footnotes(excluding those in tables and figures) shall not be consideredas requirements of the standard.1.4 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equival
6、ents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the standard.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of t
7、his 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:2D979 Practice for Sampling Bituminous Paving MixturesD1561 Practice for Preparation of Bituminous Mixture TestSpecimen
8、s by Means of California Kneading CompactorD2726 Test Method for Bulk Specific Gravity and Densityof Non-Absorptive Compacted Bituminous MixturesD3665 Practice for Random Sampling of Construction Ma-terialsD3666 Specification for Minimum Requirements for Agen-cies Testing and Inspecting Road and Pav
9、ing MaterialsD4013 Practice for Preparation of Test Specimens of Bitu-minous Mixtures by Means of Gyratory Shear CompactorD4867 Test Method for Effect of Moisture on AsphaltConcrete Paving MixturesD5361 Practice for Sampling Compacted Bituminous Mix-tures for Laboratory TestingD6752 Test Method for
10、Bulk Specific Gravity and Densityof Compacted Bituminous Mixtures Using AutomaticVacuum Sealing MethodD6925 Test Method for Preparation and Determination ofthe Relative Density of Hot Mix Asphalt (HMA) Speci-mens by Means of the Superpave Gyratory CompactorD6926 Practice for Preparation of Bituminou
11、s SpecimensUsing Marshall ApparatusD6927 Test Method for Marshall Stability and Flow ofBituminous MixturesD6931 Test Method for Indirect Tensile (IDT) Strength ofBituminous Mixtures2.2 AASHTO Standards:3AASHTO TP 79 Standard Method of Test for Determiningthe Dynamic Modulus and Flow Number for Hot M
12、ixAsphalt (HMA) Using the Asphalt Mixture PerformanceTester (AMPT)3. Significance and Use3.1 This practice provides an accelerated conditioningmethod under cyclic loading. This system is capable ofoperating at higher than normal temperatures and creating porepressure within a compacted asphalt mixtu
13、re to achieve anacceleration of the effects that a mixture would experience overtime from traffic at normal temperatures and conditions. The1This test method is under the jurisdiction of ASTM Committee D04 on Roadand Paving Materials and is the direct responsibility of Subcommittee D04.22 onEffect o
14、f Water and Other Elements on Bituminous Coated Aggregates.Current edition approved June 1, 2013. Published June 2013. DOI: 10.1520/D7870_D7870M-132For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandard
15、s volume information, refer to the standards Document Summary page onthe ASTM website.3Available from American Association of State Highway and TransportationOfficials (AASHTO), 444 N. Capitol St., NW, Suite 249, Washington, DC 20001,http:/www.transportation.org.Copyright ASTM International, 100 Bar
16、r Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1accelerated conditioning in this practice is intended to simulatethe stresses induced in a wet pavement by a passing vehicletire. The pulse shape produced by this system approximates aLorentzian function with a half peak wi
17、dth of approximately 1s at 276 kPa 40 psi.3.2 The factors that influence the potential for moisturedamage to occur include aggregate mineralogy, mixture airvoids, water, cyclic applied stress, and elevated temperature.This practice provides a method and apparatus that is capableof producing three of
18、 these factors: water, stress, and hightemperature. Aggregate mineralogy and air voids are mixtureproperties.3.3 Specimens conditioned by this system can be testedusing a variety of different tests including, Test Method D6931,Test Method D6927, bulk specific gravity difference obtainedby Test Metho
19、ds D6926 or D6752 for before and afterconditioning, dynamic modulus, flow number,AASHTO TP 79and visual inspection for stripped aggregates.NOTE 1The quality of the results produced by this standard aredependent on the competence of the personnel performing the procedureand the capability, calibratio
20、n, and maintenance of the equipment used.Agencies that meet the criteria of Practice D3666 are generally consideredcapable of competent and objective testing, sampling, inspection, etc.Users of this standard are cautioned that compliance with Practice D3666alone does not completely assure reliable r
21、esults. Reliable results dependon many factors; following the suggestions of Practice D3666 or somesimilar acceptance guideline provides a means of evaluating and control-ling some of those factors.4. Apparatus44.1 Balance in accordance with Test Method D2726.4.2 Water bath capable of maintaining a
22、temperature of 256 1C 77 6 2F.4.3 System (similar to Fig. 1) having a specimen chambercapable of testing one or more specimens with diameters of150 mm 6 in. or less. The system should be capable ofapplying a cyclic pressure peak of approximately Lorentzianfunction in shape with a peak pressure withi
23、n 630 kPa 64psi of the pressure set point and a width of the pressure peakat half maximum of 1 6 0.5 s.4.3.1 The system shall be equipped with appropriate valvesfor automatically purging (de-airing) and removing air fromthe specimen chamber and allowing replacement of the acces-sible air void spaces
24、 with water.4.3.2 The specimen chamber shall be capable of withstand-ing pressures of up to 690 kPa 100 psi.4The sole source of supply of the apparatus known to the committee at this timeis InstroTek, Inc., 5908 Triangle Drive, Raleigh, N.C. If you are aware of alternativesuppliers, please provide t
25、his information to ASTM International Headquarters.Your comments will receive careful consideration at a meeting of the responsibletechnical committee,1which you may attend.FIG. 1 Moisture Conditioning SystemD7870/D7870M 1324.3.3 The system should be equipped with temperaturecontrols to allow set po
26、int temperatures of between 30 and60C 86 to 140F with measurements accurate to within61C 62F.4.3.4 The system shall be capable of producing and control-ling cyclic pressures between 200 and 420 kPa 30 to 50 psiwith measurements accurate to within 630 kPa 64 psi.4.3.5 The system should be capable of
27、applying and con-trolling cyclic pressure and temperature and controlling thewater temperature and pressure within the enclosed specimenchamber at a desired level.4.4 One or more containers sufficient in size to hold waterand specimen(s).5. Preparation of Test Specimens5.1 Preparation of Laboratory
28、Test Specimens5.1.1 Prepare mixtures in batches of sufficient size to makeat least three specimens for each test as specified in 5.1.2.5.1.2 Use specimens 100 mm 4 in. in diameter and 63 62 mm 2.5 6 0.08 in. high or 150 mm 6 in. in diameter and100 6 5mm46 0.2 in. high. The percent air void of eachsa
29、mple used for conditioning shall be in the range of 6.5 to7.5 %. If compacting to an optimum percent air void to matchcompaction at the time of construction, all individual sampleconditioned shall not be more than 60.5 % different from theoptimum percent air void. Average the air voids of thespecime
30、ns being conditioned at one time in order to get asclose to the optimum air void value of 7 % or optimum voidlevel measured or expected in the field at the time of construc-tion. Follow the procedures in Test Method D4867 and PracticeD5361 to prepare the samples. Compact the specimens byusing any on
31、e of the following: Test Method D6925,orPractices D1561, D4013, and D6926.5.1.3 Extract the specimen from the mold and cool to roomtemperature.5.2 Preparation of Field Specimens5.2.1 Select a truck to be sampled in accordance withPractice D3665.5.2.2 Secure a specimen from the truck at the plant ina
32、ccordance with Practice D979.5.2.3 Compact the specimens in accordance with 5.1.1.6. Procedure6.1 Follow manufacturers recommendation for setting upthe moisture conditioning system. The system shall be capableof conditioning a total of three 100 mm 4 in. in diameter and63 6 2 mm 2.5 6 0.08 in. high
33、or two 150 mm 6 in. indiameter and 100 6 5mm46 0.2 in. high samples.NOTE 2Specimens with 100 mm 4 in. diameter may saturate quickerand condition differently than specimens with 150 mm 6 in. diameter.Specimen size variation should be considered when comparing results fordifferent size specimens to ea
34、ch other for a given asphalt mixture.6.2 Place the first specimen in the system and fill withsufficient water at 20 to 40C 68 to 104F water to cover thespecimen.6.3 Place a specimen plate on top of the specimen separatorspacers. Specimen separator spacers are used to ensure properseparation between
35、specimens. Place the second specimen ontop of the specimen plate (see Fig. 2). Specimen shall not bestacked directly on top of each other at anytime during or afterthe conditioning process.6.4 Pour sufficient water in the system to cover the secondspecimen. Water temperature should be less than the
36、testtemperature.6.5 Repeat section 6.4 and 6.5 if conditioning three speci-mens at one time (see Fig. 3).6.6 Fill the specimen tank with water and secure the lid.Water temperature should be less than the test temperature.FIG. 2 Two Sample ConfigurationD7870/D7870M 1336.7 Partially fill both of the o
37、verfill cups on the lid in orderto replenish the chamber with water during the de-airingprocess. De-airing will continue periodically throughout theconditioning process. The overfill cups are necessary to ensurewater is supplied to the system, as air is pushed (pumped) outof the specimen(s) during p
38、ore pressure generation.6.8 Set number of cycles to 3500.6.9 Set Pressure to 40 psi.6.10 For mixtures containing PG high temperature gradeshigher than 60, set the temperature to 60C.6.11 For mixture with PG high temperature grades less than60 and all Warm Mix Asphalt (WMA) mixtures, set tempera-ture
39、 to 50C.6.12 Allow the system to heat the water and the specimen(s)in the specimen chamber to the set point temperature, to initiatethe pressure cycle operation and complete the conditioningprocess. These steps should be automatically controlled andperformed by the system within the specified limits
40、.6.13 When the cycling process is completed, open the drainvalve and allow all water to drain. This step shall be performedautomatically by the system or manually a maximum of 20 minafter the cycling process is completed.6.14 Remove the lid.6.15 Close the drain valve, after all water has been draine
41、dfrom the chamber.6.16 Pour sufficient tap water, 18 to 27C 65 to 80F, inthe specimen chamber to cover the specimen(s). This will helpreduce the specimen(s) temperature and to ensure the speci-men(s) do not fall apart during removal from the chamber.6.17 Allow 2 to 3 min for the specimens to cool. O
42、pen thedrain valve and allow the water to drain out.6.18 Carefully remove the specimen(s) from the specimenchamber and place the specimen(s) in a water containercapable of maintaining a temperature of 25 6 1C 77 6 2Ffor 2 to 3 h. Specimens shall not be stacked or placed directlyon top of each other,
43、 during loading, unloading and condition-ing process.NOTE 3When conducting fundamental, mechanical and tensilestrength tests to determine the sensitivity of the mixture to moisturedamage and relative change in sample properties from before to afterconditioning. the test should be started no longer t
44、han six hours after thecompletion of the conditioning by this practice.7. Keywords7.1 antistripping additives; asphalt concrete paving mix-tures; cyclic stress; moisture; moisture conditioning; porepressure; tensile strength; waterFIG. 3 Three Sample ConfigurationD7870/D7870M 134ASTM International t
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47、essed to ASTM International Headquarters. 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
48、the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).D7870/D7870M 135
