ASTM D7428-2008 402 Standard Test Method for Resistance of Fine Aggregate to Degradation by Abrasion in the Micro-Deval Apparatus.pdf

1、Designation: D 7428 08Standard Test Method forResistance of Fine Aggregate to Degradation by Abrasion inthe Micro-Deval Apparatus1This standard is issued under the fixed designation D 7428; the number immediately following the designation indicates the year oforiginal adoption or, in the case of rev

2、ision, the year of last 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 This test method covers a procedure for testing fineaggregate for resistance to abrasion using the

3、 Micro-Devalapparatus.1.2 The values stated in SI units are to be regarded as thestandard.1.3 The text of this method references notes and footnoteswhich provide explanatory material. These notes and footnotes(excluding those in tables and figures) shall not be consideredas requirements of the test

4、method.1.4 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. Refer

5、enced Documents2.1 ASTM Standards:2C88 Test Method for Soundness of Aggregates by Use ofSodium Sulfate or Magnesium SulfateC117 Test Method for Materials Finer than 75-m (No.200) Sieve in Mineral Aggregates by WashingC 136 Test Method for Sieve Analysis of Fine and CoarseAggregatesC 670 Practice for

6、 Preparing Precision and Bias Statementsfor Test Methods for Construction MaterialsD 6928 Test Method for Resistance of Coarse Aggregate toDegradation by Abrasion in the Micro-Deval ApparatusE11 Specification for Wire Cloth and Sieves for TestingPurposes3. Terminology3.1 Definitions:3.1.1 constant m

7、ass, nthe condition of a test sample driedat a temperature of 110 6 5C such that it will not lose morethan 0.1 % moisture after2hofdrying.3.1.1.1 DiscussionSuch a condition of dryness can beverified by determining the mass of the sample before and aftersuccessive 2-h drying periods. In lieu of such

8、a determination,samples may be considered to have reached constant masswhen they have been dried at a temperature of 110 6 5C foran equal or longer period than that previously found adequatefor producing the desired constant mass condition under equalor heavier loading conditions of the oven.4. Summ

9、ary of Test Method4.1 The Micro-Deval Test is a measure of abrasion resis-tance and durability of mineral aggregates resulting from acombination of actions including abrasion and grinding withsteel balls in the presence of water. A 500 g sample withstandard grading is initially soaked in water for n

10、ot less thanone hour. The sample is then placed in a jar mill with 0.75 L ofwater and an abrasive charge consisting of 1250 g of 9.5-mmdiameter steel balls. The jar, aggregate, water, and charge arerevolved at 100 rpm for 15 minutes. The sample is then washedand oven dried. The loss is the amount of

11、 material passing the75 m sieve expressed as a percent by mass of the originalsample.5. Significance and Use5.1 The Micro-Deval abrasion test is a test of fine aggregateto determine abrasion loss in the presence of water and anabrasive charge. Many aggregates are more susceptible toabrasion when wet

12、 than dry, and the use of water in this testincorporates this reduction in resistance to degradation. Thetest results are helpful in evaluating the toughness/abrasionresistance of fine aggregate subject to abrasion when adequateinformation is not available from service records. This test issuitable

13、for measuring the amount of weak, soft material suchas shale or shaley carbonate in fine aggregate. Materials thatgive a low loss in this test are unlikely to exhibit significantdegradation during handling, mixing or placing. There is arelationship between drying shrinkage of cement mortar andMicro-

14、Deval abrasion loss of fine aggregate, with higher loss1This test method is under the jurisdiction of ASTM Committee D04 on Roadand Paving Materials and is the direct responsibility of Subcommittee D04.51 onAggregate Tests.Current edition approved Feb. 1, 2008. Published March 2008.2For referenced A

15、STM 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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Consho

16、hocken, PA 19428-2959, United States.materials resulting in higher drying shrinkage. Descriptions ofthe development of the test and the relationship with otherproperties have been published.3,4,55.2 The Micro-Deval abrasion test on fine aggregate isuseful for detecting changes in properties of aggre

17、gate pro-duced from an aggregate source as part of a quality control orquality assurance process.5.3 The Micro-Deval abrasion test on fine aggregate, incontrast to the version on coarse aggregate, has a significantcorrelation with the Magnesium Sulfate soundness loss of fineaggregate. The Micro-Deva

18、l test on fine aggregate has betterprecision than the sulfate soundness test, is quicker, and maybe used in place of that test. Advice on specific values forselection of aggregate will be found in the appendix.6. Apparatus6.1 Micro-Deval Abrasion Machine, a jar rolling mill asspecified in Test Metho

19、d D 6928.6.2 Containers, stainless steel Micro-Deval abrasion jars asspecified in Test Method D 6928.6.3 Abrasive ChargeMagnetic stainless steel balls arerequired. These shall have a diameter of 9.5 6 0.5 mm. Eachjar requires a charge of 1250 6 5 g of balls.NOTE 1Prior to use, new containers and new

20、 steel balls should beconditioned. Conditioning is accomplished by running the equipment witha charge of 500 g of silica sand with 750 ml of water for a period of fourhours. From time to time it may be necessary to recondition the containersand steel balls. The need for this will be indicated by sig

21、nificant reductionin loss with the calibration material. It has been found that reconditioningis usually needed when the equipment has been used for testing carbonatecoarse aggregate in the coarse aggregate version of the test (Test MethodD 6928), which may lead to polishing of the inside of the con

22、tainer andball surfaces. The conditioning process gives the containers and balls a“frosted” surface, which promotes tumbling of the balls and aggregateinside the container, rather than sliding when the containers are rotated.When silica rich fine aggregates are tested, the need for reconditioningmay

23、 be reduced or eliminated provided the calibration aggregate givessatisfactory results. For this reason, it is good practice to not usecontainers used for testing coarse aggregate in the fine aggregate versionof the test.6.4 Sieves, with square openings, and of the following sizesconforming to Speci

24、fication E11specifications: 6.7 or 6.3 mm,4.75 mm, 2.36 mm, 1.18 mm, 0.600 m, 300 m, 150 m, 75m.6.5 Oven, capable of maintaining a temperature of 110 65C.6.6 Balance, or scale accurate to 0.1 g.7. Supplies7.1 Laboratory Reference AggregateA supply of standard“Standard Sutherland Micro-Deval Fine Agg

25、regate” availablefrom the Soils and Aggregates Section, Materials EngineeringMaterials Office, Ministry of Transportation, 1201 WilsonAvenue, Downsview, Ontario, Canada M3M1J8. Fax: 1-416-235-4101. The material shall be prepared as follows:Passing Retained Mass4.75-mm 2.36-mm 40 g2.36-mm 1.18-mm 115

26、 g1.18-mm 0.600-m 180 g0.600-m 0.300-m 120 g0.300-m 150-m 38 g150-m 75-m 7 g7.2 Calibration AggregateAn adequate supply of aggre-gate, established by the Laboratory to use for calibration of thetest method (see 11.1).8. Test Sample8.1 The test sample shall be washed over a 75-m sievefollowing Test M

27、ethod C117and oven-dried at 110 6 5C toconstant mass, separated into individual size fractions inaccordance with Test Method C 136, and recombined to meetthe grading shown in 8.2.8.2 Aggregate for the test sample shall consist of materialpassing the 4.75-mm sieve, retained on the 75-m sieve with aFi

28、neness Modulus of 2.8 (Note 2). An oven dried sample of500 6 5 g shall be prepared as follows:Passing Retained Mass4.75-mm 2.36-mm 50 g2.36-mm 1.18-mm 125 g1.18-mm 0.600-m 125 g0.600-m 0.300-m 100 g0.300-m 150-m 75 g150-m 75-m 25 gNOTE 2Fine aggregates that have a fine grading give a slightly higher

29、Micro-Deval Abrasion loss than those with a coarser grading from thesame source. The effect of grading is small when the mean loss is less thanabout 20 %. For materials of low loss, which easily meet applicablespecification requirements, it may be practical to test material withoutpreparing to the g

30、rading given above for routine quality control purposes.When desired, other grading may be used but the use of such gradingshould be reported.9. Test Procedure9.1 Prepare a representative 500 6 5 g test sample inaccordance with Section 8. Weigh the test sample and recordthe Mass, A, to the nearest 0

31、.1 g.9.2 Immerse the test sample in 0.75 6 0.05 L of tap waterat a temperature 20 6 5C for a minimum of 1 h either in theMicro-Deval container or some other suitable container.9.3 Add 1250 6 5 g steel balls to the prepared test sampleand the water used to immerse the sample. Install the cover andpla

32、ce the Micro-Deval container on the machine. If anothersuitable container was used to immerse the sample, transfer theentire test sample and the water to the Micro-Deval abrasion jarand add the steel balls.9.4 Run the machine at 100 6 5 rpm for 15 min 6 5s.Ifarevolution counter is available; run the

33、 machine for 1500 6 10revolutions.9.5 Carefully pour the sample and steel balls over a 6.3 or6.7-mm sieve into a suitable container. Take care to remove the3Rogers, C., “Canadian Experience with the Micro-Deval Test for Aggregates,”Advances in Aggregates and Armourstone Evaluation, Latham, J. P., ed

34、., GeologicalSociety, London, Engineering Geology Special Publications, 13, 1998, pp. 139-147.4Rogers, C. A., Bailey, M. L., and Price, B., “Micro-Deval Test for Evaluatingthe Quality of Fine Aggregate for Concrete and Asphalt,” Transportation ResearchBoard, Washington, DC, Record 1301, 1991, pp. 68

35、-76.5Rogers, C., Lane, B., and Senior, S., “The Micro-Deval Abrasion Test forCoarse and Fine Aggregate in Asphalt Pavement,” Proceedings of Annual Sympo-sium of International Center for Aggregate Research, Austin, TX, April, 2003. Alsopublished as Ontario Ministry of Transportation Report, Materials

36、 Engineering andResearch Office Report MERO 006.D7428082entire sample from the stainless steel jar and that no aggregateis lost. Wash the steel balls retained on the sieve so that noaggregate adheres. The steel balls shall be removed from thesieve after washing. Wash the fine aggregate, recovered in

37、 thecontainer placed below the 6.3 or 6.7-mm sieve, following TestMethod C117 until the washings are clear and all materialsmaller than 75 m passes that sieve.9.6 Oven dry the washed sample to constant mass at 110 65C.9.7 Weigh the oven dry sample to the nearest 0.1 g. Recordthe Mass, B.10. Calculat

38、ion10.1 Calculate the Micro-Deval abrasion loss, as follows, tothe nearest 0.1 %.Percent Loss 5 A B! / A 3 100 (1)11. Use of the Calibration Aggregate11.1 Calibration AggregateThe Laboratory will establishan adequate supply of material to use for calibration of the testmethod.Asuitable material with

39、 a loss of between 10 and 25 %shall be established. From this material 10 samples shall betaken randomly and tested. At the same time 10 samples of“Standard Sutherland Micro-Deval Fine Aggregate” (see 7.1)shall also be tested. Provided the mean loss and variation of the“Standard Sutherland Micro-Dev

40、al Fine Aggregate” are withinallowed tolerance given below in 11.1.1, the mean value andrange obtained with the supply of the in-house calibrationaggregate shall be used thereafter. At any time a new supply ofthe in-house calibration aggregate is required, the calibrationprocedure shall be conducted

41、.11.1.1 The mean loss of the “Standard Sutherland Micro-Deval Fine Aggregate” (see 7.1) in multi-laboratory study ofthe Micro-Deval test is 16.8 %. For continued acceptance ofdata, individual test data must fall within the range 15.2 to18.4 % loss for 95 % of the time.11.1.2 When test data of the ca

42、libration aggregate is outsidethe limits established in 11.1, an investigation as to theprobable cause shall be conducted. The equipment shall bere-calibrated and the testing technique examined to detectnon-conformance with the test procedure.11.2 Every 10 samples, but at least every week in which a

43、sample is tested, a sample of the calibration aggregate shallalso be tested. The material shall be taken from a stock supplyand prepared according to 8.2. When 20 samples of calibrationmaterial have been tested, and the results show satisfactoryvariation, the frequency of testing may be changed to a

44、minimum of one sample every month.11.3 Trend Chart UseThe percent loss of the last twentysamples of calibration material shall be plotted on a trend chartin order to monitor the variation in results (Fig. 1).12. Report12.1 The report shall include the following:12.1.1 The grading used if different f

45、rom that specified.12.1.2 The percent loss of the test sample to one decimalplace.FIG. 1 Micro-Deval Abrasion Trend Chart for Calibration Aggregate SamplesD742808312.1.3 The percent loss of the calibration aggregate, testedclosest to the time at which the aggregate was tested, to thenearest 0.1 %.12

46、.1.4 The percent loss of the last twenty samples ofcalibration aggregate on a trend chart.13. Precision and Bias13.1 PrecisionFor fine aggregate with abrasion losses inthe range from 7 to 30 %, the single-operator coefficient ofvariation has been found to be 3.4 %.6Therefore, results of twoproperly

47、conducted tests on samples of the same aggregate bythe same operator using the same equipment are not expectedto differ by more than 9.6 %6of their average, 95 % of thetime. The multi-laboratory coefficient of variation has beenfound to be 8.7 %.6Therefore, the results of two properlyconducted tests

48、 by different laboratories on samples of thesame aggregate are not expected to differ by more than 24.6 %6of their average, 95 % of the time.13.2 BiasThe procedure in this test method for measuringresistance to abrasion has no bias because the resistance toabrasion can only be defined in terms of th

49、e test method.14. Keywords14.1 abrasion resistance; fine aggregate; micro-Deval; testAPPENDIX(Nonmandatory Information)X1. INTERPRETATION OF TEST RESULTSX1.1 In studies of the performance of fine aggregates in thistest, the limits in Table X1.1 have been found useful forseparating aggregates of satisfactory performance from thoseof fair or poor performance. The Ontario Ministry of Trans-portation has used these limits, with a wide variety of aggre-gates in severe climatic conditions since 1997, or earlier. Therehave been no failures or reports