AASHTO R 47-2014 Standard Practice for Reducing Samples of Hot Mix Asphalt (HMA) to Testing Size.pdf

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1、Standard Practice for Reducing Samples of Hot Mix Asphalt (HMA) to Testing Size AASHTO Designation: R 47-14 American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-2c R 47-1 AASHTO Standard Practice for Reducing Samples of

2、 Hot Mix Asphalt (HMA) to Testing Size AASHTO Designation: R 47-14 1. SCOPE 1.1. This standard practice outlines methods for the reduction of large samples of hot mix asphalt (HMA) to the appropriate size for testing, employing techniques that are intended to minimize variations in the measured char

3、acteristics between the test samples so selected and the large sample. 1.2. The values stated in SI units are to be regarded as the standard. 1.3. This standard practice may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns,

4、if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standard: T 168, Sampling Bituminous Paving Mixtures

5、 3. TERMINOLOGY 3.1. mastica mixture of asphalt binder and fine mineral material. 4. SIGNIFICANCE AND USE 4.1. Specifications for HMA mixtures require sampling portions of the material for testing. Other factors being equal, larger samples will tend to be more representative of the total supply. Thi

6、s method provides procedures for reducing the large sample obtained in the field or produced in the laboratory to a convenient size for conducting a number of tests to describe the material and measure its quality in such a manner that the smaller test sample portion is most likely to be a represent

7、ation of the larger sample, and thus of the total supply. The individual test methods provide the minimum quantity of material necessary. 5. SELECTION OF METHOD 5.1. The selection of a particular method to reduce the large sample to test size depends on the amount of material comprising the large sa

8、mple. It is recommended that for a large amount of material, a mechanical splitter be employed whenever possible, thus lessening the time needed for reduction and minimizing the loss of temperature. To further reduce the sample size, a quartering method can be utilized. 2015 by the American Associat

9、ion of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2c R 47-2 AASHTO 6. SAMPLING 6.1. Obtain samples of HMA according to T 168 or as required by individual test methods. When additional tests are to be conducted, ensure that the init

10、ial size of the field sample is adequate to accomplish all intended tests. Use similar procedures for HMA produced in the laboratory. MECHANICAL SPLITTER METHOD 7. APPARATUS 7.1. Mechanical Splitter Type AThe splitter shall have four equal-width chutes that discharge the material into four appropria

11、tely sized containers. The splitter shall be designed with a receiving hopper that will hold the HMA field sample until a handle releases the material to fall through a divider and distribute it into four equal portions. The splitter shall be designed so that the HMA field sample will flow smoothly

12、and freely through the divider without restriction or the loss of material (see Figures 1 to 3). Metric Equivalents in. mm 7 178 10 254 13.5 343 14 356 24 610 Note: All dimensions shown in inches unless otherwise noted. Figure 1Mechanical Splitter Type A 2015 by the American Association of State Hig

13、hway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2c R 47-3 AASHTO Metric Equivalents in. mm 6 152 13.5 343 Note: All dimensions shown in inches unless otherwise noted. Figure 2Plan View of Splitter a. Elevation View of Bottom Portion of Splitter

14、b. Plan View of Bottom Portion of Splitter Metric Equivalents in. mm 6 152 7 178 14 356 Note: All dimensions shown in inches unless otherwise noted. Figure 3Elevation and Plan View of Bottom Portion of Splitter 2015 by the American Association of State Highway and Transportation Officials.All rights

15、 reserved. Duplication is a violation of applicable law.TS-2c R 47-4 AASHTO 7.2. Mechanical Splitter Type BThis splitter shall have an even number of equal-width chutes (no fewer than a total of eight for a Large Splitter and no fewer than twelve for a Small Splitter), which discharge alternately to

16、 each side of the splitter. The minimum width of the individual chutes shall be approximately 50 percent larger than the largest particle to be split. The splitter shall be equipped with two receptacles to catch the two halves of the sample following splitting. It shall also be equipped with a hoppe

17、r or straight-edged pan that has a width equal to or slightly less than the overall width of the assembly of chutes, by which the sample may be fed at a controlled rate to the chutes. The splitter and accessory equipment shall be so designed that the sample will flow smoothly and freely without rest

18、riction or the loss of material (see Figure 4). a. Large Splitter for Large Samples b. Small Splitters for Small Samples Figure 4Mechanical Splitter Type B Note 1Type B mechanical splitters are commonly available in sizes adequate for HMA having a nominal maximum aggregate size not over 25.4 mm (1 i

19、n.). Use closed versions for larger sizes. 7.3. Noncontact Temperature Device (optional)A noncontact temperature device suitable for determining the temperature of a heated splitter. 7.4. Asphalt Release AgentShall not contain any solvents or petroleum-based products that could affect asphalt binder

20、 properties. 8. PROCEDURE FOR MECHANICAL SPLITTER METHOD 8.1. Place the splitter on a level surface. The splitter and accessory equipment may be heated, not to exceed 110C (230F), as determined by a noncontact temperature device. Surfaces of the mechanical splitter that will come in contact with the

21、 HMA may be lightly coated with an approved asphalt release agent to prevent a buildup and loss of asphalt binder and fines. The release agent shall not contain any solvents or petroleum-based products that could affect asphalt binder properties. 8.2. Mechanical Splitter Type APlace the field- or la

22、boratory-prepared HMA into the mechanical splitter hopper, and position four sample receptacles to receive the reduced portions of the original sample. Fill the hopper in such a manner as to avoid segregation of the HMA, typically using a continuous or segmented pour from multiple directions around

23、the hopper. Release the handle to drop the HMA through the dividers into the sample receptacles. Reintroduce selected receptacles from opposite corners into the splitter hopper as many times as necessary to further reduce the HMA sample to the size specified for the intended test. 2015 by the Americ

24、an Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2c R 47-5 AASHTO 8.3. Mechanical Splitter Type BPlace the field- or laboratory-prepared HMA into the sample splitter pan or hopper, and uniformly distribute it from edge

25、to edge so that when it is introduced into the chutes, approximately equal amounts will flow through each chute. The rate at which the sample is introduced shall be such as to allow free flow through the chutes into the receptacles below. The entire sample may be mixed by repeated use of the mechani

26、cal splitter. Reintroduce the portion of the sample from one of the receptacles into the splitter as many times as necessary to reduce the sample to the size necessary for the intended test. The portion of the material collected in the other receptacle may be reserved for reduction in size for other

27、 tests. QUARTERING METHOD 9. APPARATUS 9.1. Quartering TemplateA quartering template manufactured from a suitable metal that withstands heat and use without deforming is recommended. The template should be configured in the form of a cross with sides of equal length sufficient to be 1.1 times the di

28、ameter of a flattened cone of the HMA sample to be quartered. The height of the sides should be sufficient to extend above the thickness of the flattened cone of the HMA sample to be quartered. The sides shall form a 90-degree angle at their juncture (see Figure 5). Figure 5Quartering Device 9.2. Fl

29、at-Bottom ScoopA large, straight-edged, flat-bottom scoop should be used to sample the HMA. A square shovel or trowel will meet this requirement. 9.3. StraightedgeLarge spatula, trowel, or metal straightedge. 9.4. Nonstick paper or heat resistant plastic. 9.5. Asphalt Release AgentShall not contain

30、any solvents or petroleum-based products that could affect asphalt binder properties. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2c R 47-6 AASHTO 10. PROCEDURE FOR QUARTERING METHOD 10.1. Place t

31、he original sample on a hard, “nonstick,” clean, level surface where there will be neither a loss of material nor the accidental addition of foreign material. The surface can be made nonstick by the application of an approved asphalt release agent, nonstick paper, or heat-resistant plastic. 10.2. Mi

32、x the material thoroughly by turning the entire sample over a minimum of four times with a flat-bottom scoop or by alternately lifting each corner of the paper and pulling it over the sample diagonally toward the opposite corner, causing the material to be rolled. Create a conical pile by either dep

33、ositing each scoop or shovelful of the last turning on top of the preceding one, or lifting both opposite corners. Carefully flatten the conical pile to a uniform thickness and diameter by pressing down the apex with a shovel or large, flat-bottomed, square scoop. The diameter should be approximatel

34、y four to eight times the thickness. Make a visual observation to ensure that the material is homogeneous. 10.3. Divide the flattened mass into four quarters by inserting the quartering template and pressing down until the template is in complete contact with the surface on which the sample is place

35、d. Straightedges may be used in lieu of the quartering device to completely separate the material into approximately equal quarters. 10.4. Reduce the sample using one of the following procedures: 10.4.1. Remove two diagonally opposite quarters, including all fine mastic material. Remove the quarteri

36、ng template. Successively mix and quarter the remaining material until the sample is reduced to the desired size. 10.4.2. Using a straightedge, slice through a quarter of the HMA from the center point to the outer edge of the quarter. Pull or drag the material from the quarter holding one edge of th

37、e straightedge in contact with the quartering device. Two straightedges may be used in lieu of the quartering device. Remove an equal portion from the opposite quarter. INCREMENTAL METHOD 11. APPARATUS 11.1. Flat-Bottom ScoopA large, straight-edged, flat-bottom scoop should be used to sample the HMA

38、. A square shovel or trowel will meet this requirement. 11.2. Nonstick heavy paper or heat-resistant plastic. 11.3. Large spatulas, trowels, metal straightedge, or 305-mm (12-in.) drywall taping knife. 11.4. Miscellaneous EquipmentIncluding hot plate, non-asbestos heat-resistant gloves or mittens, p

39、ans, buckets, and cans. 12. PROCEDURE FOR INCREMENTAL METHOD 12.1. Place the original sample on a hard, nonstick, clean, level surface where there will be neither loss of material nor the accidental addition of foreign material. The surface shall be covered with a nonstick heavy paper, heat-resistan

40、t plastic, or other suitable material. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2c R 47-7 AASHTO 12.2. Mix the material thoroughly by turning the entire sample over a minimum of four times with

41、 a flat-bottom scoop or by alternately lifting each corner of the paper and pulling it over the sample diagonally toward the opposite corner, causing the material to be rolled. Create a conical pile by either depositing each scoop or shovelful of the last turning on top of the preceding one, or lift

42、ing both opposite corners. Make a visual observation to ensure that the material is homogeneous. 12.3. Grasp the paper; roll the material into a cylindrical roll (loaf), and flatten the top. 12.4. Pull the paper so that at least one-fourth of the length of the loaf is off the edge of the counter. Al

43、low this material to drop into a container. Alternately, use a straightedge to slice off approximately one-fourth of the length of the loaf and place the material in a sample pan or container. Set the material obtained aside. 12.5. Pull additional material off the edge of the counter and drop the ap

44、propriate-size sample into a sample pan or container. Alternately, use a straightedge to slice off an appropriate-size sample from the length of the loaf and place in a sample pan or container. 12.6. Repeat Section 12.5 as necessary until the proper-size sample has been obtained (Note 2). Repeat Sec

45、tions 12.4 and 12.5 until all the samples for testing have been obtained. At any time while obtaining test samples, it may be necessary to reroll the material as described in Sections 12.2 and 12.3. Note 2When reducing the sample to test size, it is advisable to take several small increments, determ

46、ining the mass each time until the proper minimum size is achieved. Unless the sample size is grossly in excess of the minimum or exceeds the maximum test size, use the sample as reduced for the test. 13. KEYWORDS 13.1. Hot mix asphalt (HMA); incremental method; quartering method; sample splitter; sample reduction; sampling. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.