1、Standard Method of Test for Bulk Specific Gravity (Gmb) of Compacted Asphalt Mixtures Using Paraffin-Coated Specimens AASHTO Designation: T 275-17 Technical Section: 2c, AsphaltAggregate Mixtures Release: Group 3 (August 2017) American Association of State Highway and Transportation Officials 444 No
2、rth Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-2c T 275-1 AASHTO Standard Method of Test for Bulk Specific Gravity (Gmb) of Compacted Asphalt Mixtures Using Paraffin-Coated Specimens AASHTO Designation: T 275-17 Technical Section: 2c, AsphaltAggregate Mixtures Release: Group 3 (August
3、2017) 1. SCOPE 1.1. This method of test covers the determination of bulk specific gravity (Gmb) of specimens of compacted asphalt mixtures. 1.2. This method should be used with samples that contain open or interconnecting voids or absorb more than 2.0 percent of water by volume, as determined by T 1
4、66. 1.3. The bulk specific gravity of the compacted asphalt mixture may be used in calculating the unit mass of the mixture. 1.4. The values stated in SI units are to be regarded as the standard. 1.5. This standard may involve hazardous materials, operations, and equipment. This standard does not pu
5、rport to address all the safety concerns, 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 regulator limitations prior to use. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards:
6、M 231, Weighing Devices Used in the Testing of Materials R 79, Vacuum Drying Compacted Asphalt Specimens T 166, Bulk Specific Gravity (Gmb) of Compacted Asphalt Mixtures Using Saturated Surface-Dry Specimens 2.2. ASTM Standard: E1, Standard Specification for ASTM Liquid-in-Glass Thermometers 3. TERM
7、INOLOGY 3.1. Definitions: 2017 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-2c T 275-2 AASHTO 3.1.1. bulk specific gravity (of solids) (Gmb)the ratio of the mass in air of a unit volume of a permeable
8、material (including both permeable and impermeable voids normal to the material) at a stated temperature to the mass in air of equal density of an equal volume of gas-free distilled water at a stated temperature. The form of the expression shall be: Bulk specific gravity (Gmb) at x/yC where: x = tem
9、perature of the material, and y = temperature of the water. 3.1.2. constant massshall be defined as the mass at which further drying does not alter the mass by more than 0.05 percent when weighed at 2-h intervals. 4. TEST SPECIMENS 4.1. Test specimens may be either laboratory-compacted asphalt mixtu
10、res or sampled from asphalt pavements. The mixtures may be surface or wearing course, binder or leveling course, or base course. 4.2. Size of SpecimensIt is recommended that: (1) the diameter of cylindrically compacted or cored specimens, or the length of the sides of sawed specimens, be at least eq
11、ual to four times the maximum size of the aggregate; and (2) the thickness of specimens be at least one and one-half times the maximum size of the aggregate. 4.3. Specimens shall be obtained from asphalt pavements with a core drill, diamond or carborundum saw, or by other suitable means. 4.4. Care s
12、hall be taken to avoid distortion, bending, or cracking of specimens during and after removal from pavement or mold. Specimens shall be stored in a safe, cool place. 4.5. Specimens shall be free from foreign materials such as seal coat, tack coat, foundation material, soil, paper, or foil. 4.6. If d
13、esired, specimens may be separated from other pavement layers by sawing or other suitable means. Care should be exercised to ensure sawing does not damage the specimens. METHOD A 5. APPARATUS 5.1. Weighing DeviceThe weighing device shall have sufficient capacity, be readable to 0.1 percent of the sa
14、mple mass or better, and conform to the requirements of M 231. The weighing device shall be equipped with a suitable suspension apparatus and holder to permit weighing the specimen while suspended from the center of the scale pan of the weighing device. 5.2. Suspension ApparatusThe wire suspending t
15、he container shall be the smallest practical size to minimize any possible effects of a variable immersed length. The suspension apparatus shall be constructed to enable the container to be immersed to a depth sufficient to cover it and the test sample during weighing. Care should be exercised to en
16、sure that no trapped air bubbles exist under the specimen. 2017 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-2c T 275-3 AASHTO 5.3. Water BathFor immersing the specimen in water while suspended under t
17、he weighing device, equipped with an overflow outlet for maintaining a constant water level, and thermostatically controlled so as to maintain the bath at 25 0.5C (77 0.9F). 6. PROCEDURE 6.1. Mass of Uncoated SpecimensDry the specimen to a constant mass at a temperature of 52 3C (125 5F). Samples sa
18、turated with water shall initially be dried overnight and then weighed at 2-h drying intervals. As an alternative to oven drying to constant mass, vacuum-dry the sample according to R 79. Recently compacted laboratory samples that have not been exposed to moisture do not require drying. Cool the spe
19、cimen to 25 5C (77 9F) and record the dry mass as A. 6.2. Mass of Coated Specimen in AirCoat the specimen on all surfaces with melted paraffin sufficiently thick to seal all surface voids. Allow the coating to cool in air at 25 5C (77 9F) for at least 30 min, and then weigh the specimen. Designate t
20、his mass as D. Note 1If it is desired to utilize the specimen for further tests that require the removal of the paraffin coating, the specimen may be dusted with powdered talc prior to coating. Note 2Application of the paraffin may be accomplished by chilling the specimen in a refrigerating unit to
21、a temperature of approximately 4.5C (40F) for at least 30 min and then dipping the specimen in warm paraffin 5.5C (10F) above the melting point. It may be necessary to brush the surface of the paraffin with added hot paraffin in order to fill any pinpoint holes. 6.3. Mass of Coated Specimen in Water
22、Immerse the coated specimen in a water bath at 25 1C (77 1.8F) for 4 1 min and record the immersed mass as E. 6.4. Specific Gravity of ParaffinDetermine the specific gravity of the paraffin at 25 1C (77 1.8F), if unknown, and designate this value as F. 7. CALCULATION 7.1. Calculate the bulk specific
23、 gravity (Gmb) of the specimen as follows. Round and report the value to the nearest three decimal places. =mbAGDADEF(1) where: A = mass of the dry specimen in air, g; D = mass of the dry specimen plus paraffin coating in air, g; E = mass of the dry specimen plus paraffin coating in water, g; and F
24、= specific gravity of the paraffin at 25 1C (77 1.8F). METHOD B 8. APPARATUS 8.1. Weighing DeviceThe weighing device shall have sufficient capacity, be readable to 0.1 percent of the sample mass or better, and conform to the requirements of M 231. 2017 by the American Association of State Highway an
25、d Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-2c T 275-4 AASHTO 8.2. Water BathThermostatically controlled, so as to maintain the bath at 25 0.5C (77 0.9F). 8.3. ThermometerASTM 17C (17F) as provided in ASTM E1, having a range of 19 to 27C (66 to 80
26、F), graduated in 0.1C (0.2F) subdivisions. 8.4. Volumeter1Calibrated to 1200 mL or an appropriate capacity depending on the size of the test sample. The volumeter shall have a tapered lid with a capillary bore. 9. PROCEDURE 9.1. Dry the specimen to a constant mass at a temperature of 52 3C (125 5F).
27、 Samples saturated with water shall initially be dried overnight and then weighed at 2-h drying intervals. As an alternative to oven drying to constant mass, vacuum-dry the sample according to R 79. Recently compacted laboratory samples that have not been exposed to moisture do not require drying. C
28、ool the specimen to 25 5C (77 9F), and record the dry mass as A. 9.2. Coat the specimen on all surfaces with melted paraffin sufficiently thick to seal all surface voids. Allow the coating to cool in air at 25 5C (77 9F) for at least 30 min, and then weigh the specimen (Notes 1 and 2). Designate thi
29、s mass as C. 9.3. Fill a calibrated volumeter with distilled water at 25 1C (77 1.8F), and weigh the volumeter. Designate this mass as D. 9.4. Place the coated specimen into the volumeter and cover the volumeter, ensuring that some water escapes through the capillary bore in the tapered lid. Wipe th
30、e outside of the volumeter dry with a dry, absorbent cloth and weigh the volumeter and its contents. Designate this mass as E. 9.5. Determine the specific gravity of the paraffin at 25 1C (77 1.8F), if unknown, and designate this value as F. 10. CALCULATIONS 10.1. Calculate the bulk specific gravity
31、 (Gmb) of the specimen as follows. Round and report the value to the nearest three decimal places. = +mbAGCAD ECF(2) where: A = mass of the dry specimen in air, g; C = mass of the dry specimen plus paraffin coating in air, g; D = mass of the volumeter filled with water at 25 1C (77 1.8F), g; E = mas
32、s of the volumeter filled with the paraffin-coated specimen and water at 25 1C (77 1.8F), g; and F = specific gravity of the paraffin at 25 1C (77 1.8F). 11. PRECISION 11.1. Duplicate specific gravity results by the same operator should not be considered suspect unless they differ by more than 0.02.
33、 2017 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-2c T 275-5 AASHTO 12. KEYWORDS 12.1. Asphalt mixture; bulk specific gravity; paraffin; paraffin coating. 1Aluminum volumeters of different sizes are available from Pine Instrument Co., 101 Industrial Drive, Grove City, PA 16127; and Rainhart Co., 604 Williams St., Austin, TX 78765. 2017 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.
