1、Standard Method of Test for Resistance of Coarse Aggregate to Degradation by Abrasion in the Micro-Deval Apparatus AASHTO Designation: T 327-121ASTM Designation: D6928-10 American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 2000
2、1 TS-1c T 327-1 AASHTO Standard Method of Test for Resistance of Coarse Aggregate to Degradation by Abrasion in the Micro-Deval Apparatus AASHTO Designation: T 327-121ASTM Designation: D6928-10 1. SCOPE 1.1. This method covers a procedure for testing coarse aggregate for resistance to abrasion using
3、 the Micro-Deval apparatus. 1.2. The values stated in SI units are to be regarded as the standard. 1.3. The text of this method references notes and footnotes that provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements
4、of the test method. 1.4. This procedure may involve hazardous materials, operations, and equipment. This procedure does not purport to address all of the safety concerns associated with its use. It is the responsibility of the user of this procedure to consult and establish appropriate safety and he
5、alth practices and determine the applicability of regulatory limitation prior to use. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: M 92, Wire-Cloth Sieves for Testing Purposes M 231, Weighing Devices Used in the Testing of Materials T 27, Sieve Analysis of Fine and Coarse Aggregates 2.2. ASTM Stan
6、dard: C670, Standard Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials 3. SUMMARY OF TEST METHOD 3.1. The Micro-Deval test is a measure of abrasion resistance and durability of mineral aggregates resulting from a combination of actions including abrasio
7、n and grinding with steel balls in the presence of water. A sample with standard grading is initially soaked in water for not less than 1 h. The sample is then placed in a jar mill with 2.0 L of water and an abrasive charge consisting of 5000 g of 9.5-mm diameter steel balls. The jar, aggregate, wat
8、er, and charge are revolved at 100 rpm for 2 h depending on the particle size. The sample is then washed and oven-dried. The loss is the amount of material passing the 1.18-mm sieve, expressed as a percent by mass of the original sample. 2015 by the American Association of State Highway and Transpor
9、tation Officials.All rights reserved. Duplication is a violation of applicable law.TS-1c T 327-2 AASHTO 4. SIGNIFICANCE AND USE 4.1. The Micro-Deval abrasion test is a test of coarse aggregates to determine abrasion loss in the presence of water and an abrasive charge. Many aggregates are more susce
10、ptible to abrasion when wet than dry, and the use of water in this test incorporates this reduction in resistance in degradation, in contrast to some other tests that are conducted on dry aggregate. The test results are helpful in evaluating the toughness/abrasion resistance of coarse aggregate subj
11、ect to abrasion when adequate information is not available from service records. 4.2. The Micro-Deval abrasion test is a useful test for detecting changes in properties of aggregate produced from an aggregate source as part of a quality control or quality assurance process. 5. TERMINOLOGY 5.1. Defin
12、ition: 5.1.1. constant masstest samples dried at a temperature of 110 5C to a condition such that it will not lose more than 0.1 percent moisture after 2 h of drying. Such a condition of dryness can be verified by weighing the sample before and after successive 2-h drying periods. In lieu of such a
13、determination, samples may be considered to have reached constant mass when they have been dried at a temperature of 110 5C for an equal or longer period than that previously found adequate for producing the desired constant mass condition under equal or heavier loading conditions of the oven. 6. AP
14、PARATUS 6.1. Micro-Deval Abrasion MachineA jar rolling mill capable of running at 100 5 rpm (see Figure 1). Note 1Micro-Deval abrasion machine fitted with a counter may be used if the test is conducted on the basis of number of revolutions (Section 9.4). 2015 by the American Association of State Hig
15、hway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-1c T 327-3 AASHTO Note: All dimensions are shown in millimeters unless otherwise noted. Figure 1Micro-Deval Abrasion Machine and Container 6.2. ContainersStainless steel Micro-Deval abrasion jars h
16、aving a 5-L capacity with a rubber ring in the rotary locking cover; an external diameter of 194 to 202 mm, and an internal height of 170 to 177 mm. The inside and outside surfaces of the jars shall be smooth and have no observable ridges or indentations (Figure 1). 6.3. Abrasion ChargeMagnetic stai
17、nless steel balls are required. These shall have a diameter of 9.5 0.5 mm. Each jar requires a charge of 5000 5 g of balls. 6.4. SievesSieves with square openings, and of the following sizes conforming to M 92 specifications: 19.0 mm, 16.0 mm, 12.5 mm, 9.5 mm, 6.3 mm, 4.75 mm, 1.18 mm. 6.5. OvenThe
18、oven shall be capable of maintaining a temperature of 110 5C. 6.6. BalanceA balance or scale accurate to 1.0 g. Cylindrical JarVolume: 5.03L200MotorMotor Base310515ShieldFrameChainCogged WheelV-BeltReducing Gear425900340176Drive RollerDriven Roller178 2015 by the American Association of State Highwa
19、y and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-1c T 327-4 AASHTO 7. REFERENCE AGGREGATE 7.1. Reference AggregateAn adequate supply of aggregate, established by the laboratory to use for monitoring testing consistency through the establishment of c
20、ontrol limits (see Section 11.1). 8. TEST SAMPLE 8.1. The test sample shall be washed and oven-dried at 110 5C to constant mass, separated into individual size fractions in accordance with T 27, and recombined to meet the grading as shown in Section 8.2. 8.2. Aggregate for the test shall normally co
21、nsist of material passing the 19.0-mm sieve, retained on the 9.5-mm sieve. An oven-dried sample of 1500 5 g shall be prepared as in Table 1. Table 1Preparation of an Oven-Dried Sample of 19.0 mm Passing Retained Mass 19.0 mm 16.0 mm 375 g 16.0 mm 12.5 mm 375 g 12.5 mm 9.5 mm 750 g 8.3. In a case whe
22、re the nominal maximum size of the coarse aggregate is 12.5 mm or less, a sample of 1500 5 g shall be prepared as in Table 2: Table 2Preparation of an Oven-Dried Sample of Less Than 16.0 mm Passing Retained Mass 12.5 mm 9.5 mm 750 g 9.5 mm 6.3 mm 375 g 6.3 mm 4.75 mm 375 g 8.4. In a case where the n
23、ominal maximum size of the coarse aggregate is 9.5 mm or less, a sample 1500 5 g shall be prepared as in Table 3: Table 3Preparing an Oven-Dried Sample of Less Than 12.5 mm Passing Retained Mass 9.5 mm 6.3 mm 750 g 6.3 mm 4.75 mm 750 g 9. TEST PROCEDURE 9.1. Prepare a representative 1500 5-g sample.
24、 Determine the Mass “A” and record to the nearest 1.0 g. 9.2. Immerse the sample in 2.0 0.05 L of tap water at a temperature of 20 5C for a minimum of 1 h either in the Micro-Deval container or some other suitable container. 2015 by the American Association of State Highway and Transportation Offici
25、als.All rights reserved. Duplication is a violation of applicable law.TS-1c T 327-5 AASHTO 9.3. Place the sample in the Micro-Deval abrasion container with 5000 5 g of steel balls and the water used in Section 9.2 to saturate the sample. Install the cover and place the Micro-Deval container on the m
26、achine. 9.4. Run the machine at 100 5 rpm for 12,000 100 revolutions for the grading shown in Section 8.2; for 10,500 100 revolutions for the grading shown in Section 8.3; and for 9500 100 revolutions for the grading shown in Section 8.4. Note 2Some equipment is not capable of measuring the total nu
27、mber of revolutions of the drum. If desired, instead of using revolutions, time can be used as follows: Run the machine at 100 5 rpm for 120 1 min for the grading shown in Section 8.2. For the grading shown in Section 8.3, run the machine for 105 1 min. For the grading shown in Section 8.4, run the
28、machine for 95 1 min. 9.5. Carefully pour the sample and steel balls over a 4.75-mm sieve superimposed on a 1.18-mm sieve. Take care to remove the entire sample from the stainless steel jar. Wash and manipulate the retained material on the sieve with water using a handheld water hose and the hand un
29、til the washings are clear and all material smaller than 1.18 mm passes that sieve. Remove the stainless steel balls using a magnet or other suitable means. Discard material smaller than 1.18 mm. 9.6. Combine the material retained on the 4.75-mm and 1.18-mm sieves, being careful not to lose any mate
30、rial. 9.7. Oven-dry the sample to constant mass at 110 5C. 9.8. Weigh the sample to the nearest 1.0 g. Record the Mass “B.” 10. CALCULATIONS 10.1. Calculate the Micro-Deval abrasion loss, as follows, to the nearest 0.1 percent: Percent Loss = (A B)/A 100 (1) where: A = mass, as determined in Section
31、 9.1; and B = mass, as determined in Section 9.8. 11. USE OF THE REFERENCE AGGREGATE 11.1. Reference AggregateThe laboratory will establish an adequate supply of material to use for monitoring testing consistency through the establishment of control limits. A suitable material with an average loss o
32、f between 15 and 25 percent shall be established. From this material, 10 samples shall be taken randomly and tested. At any time a new supply is required, this procedure shall be conducted on a new supply. 11.1.1. The mean loss and sample standard deviation of the reference aggregate (see Section 7.
33、1) shall be determined from the 10 tests in Section 11.1. 11.1.2. For continued acceptance of data, individual reference aggregate test data must fall within the range of 2 standard deviations of the mean percent loss 95 percent of the time. When test data of the reference aggregate is outside the l
34、imits, an investigation as to the probable cause shall be conducted. The equipment shall be checked and the testing technique re-examined to detect nonconformance with the test procedure. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication
35、is a violation of applicable law.TS-1c T 327-6 AASHTO 11.2. Every 10 samples, but at least every week in which a sample is tested, a sample of the reference aggregate shall be tested. The material shall be taken from a stock supply and prepared according to Section 8. When 20 samples of reference ag
36、gregate have been tested, and the results show satisfactory variation, the frequency of testing may be changed to a minimum of one sample every month. 11.3. Trend Chart UseThe percent loss of the last 20 samples of reference aggregate shall be plotted on a trend chart in order to monitor the variati
37、on in results (see Figure 2). The Upper and Lower Range Limits are defined as 2 standard deviations of the mean percent loss established from Section 11.1.1. Figure 2Micro-Deval Abrasion Trend Chart for Reference Aggregate Samples 12. REPORT 12.1. The report shall include the following: 12.1.1. The
38、maximum size of the aggregate tested and the grading used; 12.1.2. The percent loss of the test sample to one decimal place; 12.1.3. The percent loss of the reference aggregate, tested closest to the time at which the aggregate was tested, to the nearest 0.1 percent; and 12.1.4. The percent loss of
39、the last 20 samples of reference aggregate on a trend chart. 13. PRECISION AND BIAS 13.1. PrecisionThe multilaboratory precision has been found to vary over the range of values obtained in this test. The figures given in Column 2 of Table 4 are the coefficients of variation that have been found to b
40、e appropriate for the materials described in Column 1. The figures given in Jan 1 Test Number Dec 31Test MethodMean = 19.1Upper Range Limit = 20.7MDALoss (%)Micro-Deval Abrasion: Trend ChartReference Aggregate1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20Lower Range Limit = 17.523.022.021.020.01
41、9.018.017.016.015.0 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-1c T 327-7 AASHTO Column 3 are the limits that should not be exceeded by the difference between the results of two properly conducte
42、d tests on the same sample expressed as a percent of their mean, 95 percent of the time. Table 4Multilaboratory Precision Aggregate Abrasion Loss, % Coefficient of Variation, % of MeanaAcceptable Range of Two Results, % of Meana5 10.0 28 12 6.4 18 17 5.6 16 21 5.3 15 aThese numbers represent, respec
43、tively, the (1s percent) and (d2s percent) limits as described in ASTM C670. 13.2. BiasThe procedure in this test method for measuring resistance to abrasion has no bias because the resistance to abrasion can only be defined in terms of the test method. 14. KEYWORDS 14.1. Abrasion resistance; coarse
44、 aggregate; Micro-Deval. 15. REFERENCES 15.1. Rogers, C. “Canadian Experience with the Micro-Deval Test for Aggregates.” In Advances in Aggregates and Armourstone Evaluation. Latham, J. P. (ed). Geological Society, London, Engineering Geology Special Publications, 13, 1998, pp. 139147. 15.2. Kandhal
45、, P. S. and F. Parker, Jr. Aggregate Tests Related to Asphalt Concrete Performance in Pavements. Final Report prepared for National Cooperative Highway Research Program, Transportation Research Board, Washington, DC, May 1997. APPENDIX (Nonmandatory Information) X1. INTERPRETATION OF TEST RESULTS X1
46、.1. In studies of the performance of aggregates in this test (Rogers, 1998; Kandhal and Parker, 1997), the limits in Table X1.1 have been found useful for separating aggregates of satisfactory performance from those of fair or poor performance. 2015 by the American Association of State Highway and T
47、ransportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-1c T 327-8 AASHTO Table X1.1Limits of Satisfactory Performance of Aggregates Application Maximum Micro-Deval Abrasion Loss, % Granular subbase 30aGranular base 25aOpen graded base course 17aAsphalt concrete
48、base course and secondary surface course 21aAsphalt concrete surface course 17a18ba Rogers, 1998 (See Section 15.1.) b Kandhal and Parker, 1997 (See Section 15.2.) 1Except for Sections 7 and 11, this test method is technically equivalent to ASTM D6928-10. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.
