1、Designation: D 4125 05Standard Test Methods forAsphalt Content of Bituminous Mixtures by the NuclearMethod1This standard is issued under the fixed designation D 4125; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last
2、 revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 These test methods cover the procedures for determin-ing the asphalt content of samples of uncompacted bituminousmixtures
3、 (Test Method A), and of laboratory compactedspecimens of bituminous mixtures (Test Method B) by exam-ining a test sample with an apparatus that utilizes neutronthermalization techniques.1.2 The values expressed in SI units are regarded as thestandard. The inch-pounds equivalents may be approximate.
4、1.3 A precision and bias statement for Method B in thisstandard has not been developed at this time. Therefore,Method B should not be used for acceptance or rejection of amaterial for purchasing purposes.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with
5、 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. See Section 6 and8.4.2, 8.5.6, and Note 4, for specific hazards.2. Referenced Documents2.1 ASTM Standards:2C 6
6、70 Practice for Preparing Precision and Bias Statementsfor Test Methods of Construction MaterialsD75 Practice for Sampling AggregatesD 140 Practice for Sampling Bituminous MaterialsD 979 Practice for Sampling Bituminous Paving MixturesD 1461 Test Method for Moisture or Volatile Distillates inBitumin
7、ous Paving MixturesD 1559 Test Method for Resistance to Plastic Flow ofBituminous Mixtures Using Marshall Apparatus3D 1561 Practice for Preparation of Bituminous Mixture TestSpecimens by Means of California Kneading CompactorD 3387 Test Method for Compaction and Shear Propertiesof Bituminous Mixture
8、s by Means of the U.S. Corps ofEngineers Gyratory Testing Machine (GTM)D 4013 Practice for Preparation of Test Specimens of Bitu-minous Mixtures by Means of Gyratory Shear Compactor3. Significance and Use3.1 These test methods are useful as a rapid, nondestructivetechnique for determination of aspha
9、lt content of bituminousmixtures.3.2 These test methods are suitable for quality control andacceptance testing for construction and for research anddevelopment applications. The test method is used for deter-mination of asphalt content only as it does not provideextracted aggregate for gradation ana
10、lysis.3.3 The non-destructive nature of the test allows repetitivemeasurements to be made on a single test sample for statisticalanalysis of test data.3.4 These test methods determine the asphalt content of atest sample by comparing the measured asphalt content withpreviously established calibration
11、 data.3.4.1 The asphalt content of a material expressed as apercentage, is the ratio of the mass of asphalt in a given massof material to the total mass of the sample or to the mass of thesolid material particles.4. Interferences4.1 The fundamental assumptions inherent in this testmethod are that th
12、e material under test is homogeneous andthat hydrogen present is in the form of asphalt or has beenotherwise accounted for in the calibration process.1These test methods are under the jurisdiction of ASTM Committee D04 onRoad and Paving Materials and is the direct responsibility of Subcommittee D04.
13、25on Analysis of Bituminous Mixtures.Current edition approved June 1, 2005. Published July 2005. Originally approvedin 1983. Last previous edition approved in 2000 as D 4125 94 (2000).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm
14、.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.2 Accurate results will be dependent upon proper
15、calibra-tion of the apparatus to the material being tested.4.3 This apparatus measures the total amount of hydrogen inthe sample including hydrogen present in the form of water.Unless the test sample is free of water, such percentage must bedetermined in accordance with the provisions of Test Method
16、D 1461 and the percentage determined subtracted from theasphalt percentage as measured by the apparatus.4.3.1 Alternatively, the sample may be dried to a constantmass in an oven at 110 6 5C (230 6 9F), thereby nullifyingthe need for the correction.4.4 This apparatus may be sensitive to outside influ
17、ences,therefore, any other source of neutron radiation shall be kept atleast 10 m (30 ft) from the apparatus during use. The areaaround the apparatus shall be kept free of large amounts ofhydrogenous material, such as water, plastics, or asphalt duringuse.4.5 Moving the apparatus to a different loca
18、tion, even withinthe same laboratory, can cause a change in backgroundradiation measurements. Also, if objects containing hydrog-enous materials are moved in the area near the apparatus, themeasurement counts may be affected. New background mea-surements shall be taken prior to use whenever backgrou
19、ndconditions have changed (see Section 10).5. Apparatus5.1 While exact details of construction for the apparatusmay vary, the system shall consist of the following items:5.1.1 Neutron SourceAn encapsulated and sealed radio-active source such as americium/beryllium.5.1.2 DetectorsAny type of thermal
20、neutron detectors,such as helium-3 or boron trifluoride.5.1.3 Read-Out Instrument, such as a scaler or a directreading digital device calibrated in percent asphalt.5.2 Other Apparatus:5.2.1 Stainless Steel Sample Pans, of uniform size andmass.5.2.2 Balance, capable of weighing to 20 kg (44 lb),reada
21、ble to 1 g (0.0002 lbm).5.2.3 Oven, capable of heating to 177 6 3C (350 6 5F).5.2.4 Straightedge, steel, approximately 450 mm (18 in.) inlength.5.2.5 Flat Plate, metal or wood, having an area slightlylarger than the sample pan. The metal plate shall have aminimum thickness of 10 mm (38 in.). The woo
22、den plate shallhave a minimum thickness of 20 mm (34 in.).5.2.6 Assorted Spoons and Mixing Bowls.5.2.7 Thermometer with a temperature range of 10 to250C (50 to 482F).5.3 Additional Apparatus for Test Method B:5.3.1 Molded Laboratory Specimen Container, (provided byinstrument manufacturer) to allow f
23、or proper testing of labo-ratory compacted samples (see Fig. 1).5.3.2 Apparatus, necessary to prepare compacted specimensas specified in Test Methods D 1559, D 1561, D 3387,orPractice D 4013.6. Hazards6.1 WarningThis equipment utilizes radioactive materi-als which may be hazardous to the health of t
24、he users unlessproper precautions are taken. Users of this equipment mustbecome completely familiar with possible safety hazards andwith all applicable regulations concerning the handling and useof radioactive materials. Effective user instructions togetherwith routine safety procedures are a recomm
25、ended part of theoperation of this apparatus.7. Sampling7.1 Obtain random samples of aggregates in accordancewith Practice D75.7.2 Obtain random samples of freshly produced bituminouspaving mixture in accordance with Practice D 979.7.3 Obtain random samples of bituminous materials inaccordance with
26、Practice D 140.8. Calibration8.1 The test results obtained using this test method will beinfluenced by the types of aggregate, source, and grade ofasphalt, and by the mix gradation. Accordingly, a calibrationcurve must be developed for each mix type and aggregateblend to be tested under this test me
27、thod.8.1.1 A new calibration curve shall be developed wheneverthere is a change in the source of asphalt or aggregate or asignificant change in aggregate gradation.8.1.2 Anew calibration curve shall be established for new orrepaired apparatus.8.2 For Test Method A, calibrate the apparatus using thef
28、ollowing procedures:FIG. 1 Molded Laboratory Specimen-Containers MeasurementValues in SI Units (CM)Other Values for Reference OnlyD41250528.2.1 Sample the aggregates in accordance with 7.1 andblend the aggregates in the proper proportions. Obtain enoughaggregate for a minimum of three samples. Appro
29、ximately 30kg (65 lb) will be required, and8.2.2 Sample the bituminous materials in accordance with7.3. Approximately 2.5 kg (5.5 lb) will be required.8.3 Use a minimum of three prepared samples to establishthe calibration curve. The range of asphalt contents shall varyby at least two percent asphal
30、t content from the lowest to thehighest contents in the samples. The range shall encompass theasphalt content of the proposed mix design. The mass of thesamples shall be within 10 g of each other.8.3.1 Unless the apparatus makes provision for temperaturecorrections, all calibration samples shall be
31、tested at a uniformtemperature, within 65C (9F). Calibration samples shouldbe prepared and tested as close as possible to the temperatureof test samples of completed mixes.8.4 Prepare a blank sample (sample of hot, dry aggregatewithout asphalt) to determine the mass to be used for calibra-tion and p
32、lant mix samples. Using this mass will ensure thesame average density for all test samples.8.4.1 Thoroughly mix at least 10 kg (22 lb) of the aggregateafter heating and drying it to a constant mass and temperature.8.4.2 Fill a sample pan with the aggregate in two or threelayers, avoiding segregation
33、. Using a scoop or spatula, distrib-ute the aggregate to reduce voids and segregation. For eachlayer raise the pan approximately 20 to 50 mm (1 to 2 in.) fromthe working surface and tap the pan against the workingsurface two or three times to settle the contents. Fill the pan toa point slightly abov
34、e the top edge. Slide a straightedge alongthe top of the pan until the aggregate is absolutely flush withthe top edge of the pan. (CautionDo not compact thesample.)8.4.3 Determine the mass of the blank sample to the nearestgram and record data. Use this mass for all calibration andplant mix test sam
35、ples. (See Note 2.)8.4.4 Place the pan containing the blank sample in theapparatus and take a measurement in accordance with themanufacturers instructions.8.4.5 Record the blank sample count.8.4.6 To detect changes in aggregate that may affect testresults, a sample of aggregate may be prepared and t
36、ested eachday as described herein. If a significant change in the count(60.5 %) has occurred, then check the calibration as describedin 9.3. If necessary, prepare a new calibration curve as outlinedin 8.5 (see Note 1).NOTE 1Batch plant hot bin samples may be used to obtain the dryaggregate count. Ca
37、re must be taken to ensure that the aggregate iscompletely dried and properly mixed before testing when using hot binsamples.8.5 Prepare a minimum of three calibration samples usingthe following procedures:8.5.1 Heat the aggregates and asphalt cement to approxi-mately 150C (300F). Heat all bowls, sa
38、mple pans, and toolsto approximately 150C (300F).8.5.2 To prevent samples from being biased by residualasphalt retained in the mixing bowl, do not clean the bowl aftereach mixing of the samples. Scrape it clean, leaving a coatingof asphalt mix residue. This allows for a more accurate mixingof sample
39、s. Prior to mixing the first sample, a mixture ofasphalt and aggregate fines may be used as a light coating onthe interior of the mixing bowl.8.5.3 Using an aggregate sample of sufficient size to fill thesample pan, add the proper amount of asphalt (within1gofdesired percent by mass) and mix thoroug
40、hly in the mixingbowl.8.5.4 Fill the sample pan in three layers. After placing eachlayer in the sample pan, using a scoop or spatula, distribute thelayer of material evenly in the pan to reduce voids andsegregation. Lift the pan approximately 20 to 50 mm (1 to 2in.) and tap it on the working surface
41、 two or three times tosettle the contents. The last layer should fill the pan to a pointslightly above the top edge.8.5.5 Determine the mass of the sample and add or subtractmaterial until the mass is within 10 g of the mass of the blanksample.NOTE 2The mass of the blank sample may not be sufficient
42、 tocompletely fill the calibration and plant mix test sample pans for all mixes.The asphalt cement may act as a lubricant allowing additional consolida-tion of the aggregate particles. An adjusted blank sample mass may bedetermined by preparing a calibration sample using these procedures andusing th
43、e mass of this sample as the blank sample mass for this and allremaining samples.8.5.6 Using a flat plate of wood or metal as a press,compress the sample until it is level with the top edge of thepan. Waxed paper may be used under the press to preventasphalt sticking to the press. (CautionThis is th
44、e onlycompactive effort the sample should receive.)8.5.7 Place the sample in the apparatus and take a timedmeasurement in accordance with the manufacturers instruc-tions.8.5.8 Repeat this process for the remainder of the calibrationsamples.8.6 For Test Method B calibrate the apparatus using thefollo
45、wing procedures:8.6.1 Sample the aggregates in accordance with 7.1 andprepare for blending in accordance with the laboratory com-pacted method to be used,8.6.2 Sample the bituminous materials in accordance with7.3.8.6.3 At a minimum of four (4) known asphalt contents,prepare at least three (3) compa
46、cted specimens using TestMethods D 1559, D 1561, D 3387, or Practice D 4013. Varythe range of asphalt contents by at least 2 % from the lowest tothe highest. The masses of each set of replicate specimens shallbe within 10 g of each other.NOTE 3Specimens prepared for other purposes such as determinin
47、gthe laboratory mix design of bituminous mixtures may be used in thisprocedure, however, no other testing of the specimens should be doneprior to performing this procedure.8.6.3.1 Determine the mass of each specimen to the nearestgram,8.6.4 For 10-cm (4-in.) specimens, select the two (2) speci-mens
48、at each asphalt content having the mass nearest eachother. For 15-cm (6-in.) specimens, select the one (1) specimenof each set that has a mass closest to the mass of the otherD4125053specimens to be tested. The specimens not used in this processshould be retained for use in other testing procedures
49、inaccordance with Note 3,8.6.5 Place the specimens in the molded laboratory speci-men container and place the container in the apparatus. Taketimed measurements in accordance with the manufacturersinstructions, and8.6.6 Repeat this process with each of the other three sets ofcalibration samples.8.7 When using this procedure to prepare calibration curvesfor mixes containing recycled asphalt pavement (RAP) mate-rials, the RAP material shall be of a uniform gradation, asphaltcontent, and asphalt type. In preparing calibration samples, thesame percentage of RAP
