1、Standard Method of Test for Theoretical Maximum Specific Gravity (Gmm) and Density of Hot Mix Asphalt (HMA) AASHTO Designation: T 209-12 American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-2c T 209-1 AASHTO Standard Me
2、thod of Test for Theoretical Maximum Specific Gravity (Gmm) and Density of Hot Mix Asphalt (HMA) AASHTO Designation: T 209-12 1. SCOPE 1.1. This test method covers the determination of the theoretical maximum specific gravity/gravity mix maximum (Gmm) and density of uncompacted hot mix asphalt (HMA)
3、 at 25C (77F). Note 1The precision of the method is best when the procedure is performed on samples that contain aggregates that are completely coated. In order to assure complete coating, it is desirable to perform the method on samples that are close to the optimum asphalt binder content. 1.2. The
4、 values stated in SI units are to be regarded as the standard. 1.3. This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard t
5、o establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: M 231, Weighing Devices Used in the Testing of Materials R 47, Reducing Samples of Hot Mix Asphalt (HMA) to Testing Size R 61, Es
6、tablishing Requirements for Equipment Calibrations, Standardizations, and Checks T 168, Sampling Bituminous Paving Mixtures 2.2. ASTM Standards: C670, Standard Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials D4311/D4311M, Standard Practice for Determi
7、ning Asphalt Volume Correction to a Base Temperature 3. TERMINOLOGY 3.1. Definitions: 3.1.1. density, as determined by this test methodthe mass of a cubic meter of the material at 25C (77F) in SI units, or the mass of a cubic foot of the material at 25C (77F) in inch-pound units. 3.1.2. residual pre
8、ssure, as employed by this test methodthe pressure in a vacuum vessel when vacuum is applied. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2c T 209-2 AASHTO 3.1.3. specific gravity, as determined b
9、y this test methodthe ratio of a given mass of material at 25C (77F ) to the mass of an equal volume of water at the same temperature. 4. SUMMARY OF TEST METHOD 4.1. A weighed sample of oven-dry HMA in the loose condition is placed in a tared vacuum container. Sufficient water at a temperature of 25
10、 0.5C (77 0.9F) is added to completely submerge the sample. Vacuum is applied for 15 2 min to gradually reduce the residual pressure in the vacuum container to 3.7 0.3 kPa (27.5 2.5 mmHg). At the end of the vacuum period, the vacuum is gradually released. The volume of the HMA sample is obtained eit
11、her by immersing the vacuum container with the sample into a water bath and determining the mass (Section 13.1) or by filling the vacuum container level full of water and determining the mass in air (Section 13.2). At the time of weighing, the temperature is measured as well as the mass. From the ma
12、ss and volume measurements, the specific gravity or density at 25C (77F) is calculated. If the temperature employed is different than 25C (77F), an appropriate correction is applied. 5. SIGNIFICANCE AND USE 5.1. The theoretical maximum specific gravities and densities of HMA are intrinsic properties
13、 whose values are influenced by the composition of the mixtures in terms of types and amounts of aggregates and asphalt materials. 5.1.1. These properties are used to calculate percent air voids in compacted HMA. 5.1.2. These properties provide target values for the compaction of HMA. 5.1.3. These p
14、roperties are essential when calculating the amount of asphalt binder absorbed by the internal porosity of the individual aggregate particles in HMA. 6. APPARATUS 6.1. Follow the procedures for performing equipment calibrations, standardizations, and checks found in R 61. 6.2. Vacuum Container: 6.2.
15、1. The vacuum containers described must be capable of withstanding the full vacuum applied, and each must be equipped with the fittings and other accessories required by the test procedure being employed. The opening in the container leading to the vacuum pump shall be covered by a piece of 0.075-mm
16、 (No. 200) wire mesh to minimize the loss of fine material. 6.2.2. The capacity of the vacuum container should be between 2000 and 10 000 mL and depends on the minimum sample size requirements given in Section 7.2. Avoid using a small sample in a large container. 6.2.3. Vacuum BowlEither a metal or
17、plastic bowl with a diameter of approximately 180 to 260 mm (7 to 10 in.) and a bowl height of at least 160 mm (6.3 in.) equipped with a transparent cover tted with a rubber gasket and a connection for the vacuum line. 6.2.4. Vacuum Flask for Mass Determination in Air Only (Section 13.2)A thick-wall
18、ed volumetric glass ask and a rubber stopper with a connection for the vacuum line. 6.2.5. Pycnometer for Mass Determination in Air OnlyA glass, metal, or plastic pycnometer. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violatio
19、n of applicable law.TS-2c T 209-3 AASHTO 6.3. BalanceA balance conforming to the requirements of M 231, Class G 2. The balance shall be standardized at least every 12 months. 6.3.1. For the mass determination-in-water method (Section 13.1), the balance shall be equipped with a suitable apparatus and
20、 holder to permit determining the mass of the sample while suspended below the balance. The wire suspending the holder shall be the smallest practical size to minimize any possible effects of a variable immersed length. 6.4. Vacuum Pump or Water AspiratorCapable of evacuating air from the vacuum con
21、tainer to a residual pressure of 4.0 kPa (30 mmHg). 6.4.1. When a vacuum pump is used, a suitable trap of one or more filter flasks, or equivalent, shall be installed between the vacuum vessel and vacuum source to reduce the amount of water vapor entering the vacuum pump. 6.5. Vacuum Measurement Dev
22、iceResidual pressure manometer1or vacuum gauge to be connected directly to the vacuum vessel and capable of measuring residual pressure down to 4.0 kPa (30 mmHg) or less (preferably to zero). The gauge shall be standardized at least annually and be accurate to 0.1 kPa (1 mmHg). It shall be connected
23、 at the end of the vacuum line using an appropriate tube and either a “T” connector on the top of the vessel or a separate opening (from the vacuum line) in the top of the vessel to attach the hose. To avoid damage, the manometer shall not be situated on top of the vessel. Note 2A residual pressure
24、of 4.0 kPa (30 mmHg) absolute pressure is approximately equivalent to a 97 kPa (730 mmHg) reading on a vacuum gauge at sea level. Note 3Residual pressure in the vacuum container, measured in millimeters of mercury, is the difference in the height of mercury in the Torricellian vacuum leg of the mano
25、meter and the height of mercury in the other leg of the manometer that is attached to the vacuum container. Note 4An example of a correct arrangement of the testing equipment is shown in Figure 1. In the figure, the purpose of the train of small filter flasks is to trap water vapor from the vacuum c
26、ontainer that otherwise would enter the oil in the vacuum pump and decrease the pumps ability to provide adequate vacuum. Insertion of a valve to isolate the line to each vacuum chamber can reduce wear on the bleeder valve atop each chamber and assist in tracing sealing leaks. Figure 1Example of Cor
27、rect Arrangement of Testing Apparatus 6.6. Bleeder Valveattached to the vacuum train to facilitate adjustment of the vacuum being applied to the vacuum container. 6.7. Thermometric Device (Mass Determination in Air)A liquid-in-glass thermometer or other thermometric device, accurate to 0.5C (1F), of
28、 suitable range with subdivisions of 0.5C (1F). The thermometric device shall be standardized at the test temperature at least every 12 months. VacuumSource3-1000 cc Filter Flasks for Water Vapor TrapFlow of Exhausted Airand Water VaporBleeder ValveResidual Pressure Manometer2000 cc Filter FlaskVacu
29、um VesselWaterPaving Mixture Sample 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2c T 209-4 AASHTO 6.8. Water Bath: 6.8.1. For vacuum bowls, a water bath capable of maintaining a constant temperatu
30、re between 20 and 30C (68 and 86F) is required. (See Appendix X1 for a method for correcting the theoretical maximum specific gravity to 25C (77F) when measurements are made at temperatures other than 25C (77F). 6.8.2. Thermometric Device (Mass Determination in Water)A liquid-in-glass thermometer or
31、 other thermometric device, accurate to 0.5C (1F) shall be used to measure the temperature of the water bath. The thermometric device shall be standardized at least every 12 months. 6.8.3. When using the mass determination-in-water technique (Section 13.1), the water bath must be suitable for immers
32、ion of the suspended container with its deaerated sample. 6.9. Drying OvenA thermostatically controlled drying oven capable of maintaining a temperature of 135 5C (275 9F) or 105 5C (221 9F). 6.9.1. Thermometric DeviceA liquid-in-glass thermometer or other thermometric device accurate to 3C (5F) sha
33、ll be used to measure the temperature of the oven. The thermometric device shall be standardized at least every 12 months. 6.10. Protective GlovesUsed when handling glass equipment under vacuum. 7. SAMPLING 7.1. Field samples shall be obtained in accordance with T 168. When necessary, reduce field s
34、amples or samples prepared or produced in a laboratory in accordance with R 47. 7.2. The size of the sample shall conform to the following requirements. Samples larger than the capacity of the container may be tested a portion at a time. Table 1Minimum Sample Sizes Nominal Maximum Aggregate Size, mm
35、 Minimum Sample Size, g 37.5 or greater 4000 19 to 25 2500 12.5 or smaller 1500 8. STANDARDIZATION OF FLASKS, BOWLS, AND PYCNOMETERS 8.1. For the mass determination-in-water method (Section 13.1), standardize the vacuum bowls for temperature correction by determining the mass of each container when
36、immersed in water over the range of water bath temperatures likely to be encountered in service (Figure 2). 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2c T 209-5 AASHTO Figure 2Example Standardiz
37、ation Curve for Volumetric Flask 8.2. For the mass determination-in-air method (Section 13.2), standardize the volumetric flasks or pycnometers for temperature correction by determining the mass of the container when filled with water over the range of water bath temperatures likely to be encountere
38、d in service (Figure 3). When standardized at 25 0.5C (77 0.9F), designate this mass as D. Accurate filling may be ensured by the use of a glass cover plate. Temperature of Water Bath, C11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 316096106116126136146156166176186196206216226236246256
39、26627628629630631632MassofFlaskImmersed inWater, gFlask No.2Flask No.1 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2c T 209-6 AASHTO Figure 3Example Standardization Curve for Pycnometer 8.3. Stand
40、ardize the large-size plastic pycnometer by accurately determining the mass of water required to fill it over a range of temperature from about 20 to 65C (70 to 150F), and construct a standardization curve of mass versus temperature as shown in Figure 3. Care should be taken to follow exactly the sa
41、me procedure in standardization as in conducting a test. 8.3.1. The following filling procedure may be used for the model with a latched lid and vented stopper: The domed lid is latched in place and the pycnometer nearly filled with water. Leave about 50 mm (2 in.) empty. The release of air bubbles
42、may be facilitated by applying vacuum and by dropping first one side then the other of the pycnometer about 10 mm (1/2in.) above a hard, flat surface. This vacuum application and bubble release procedure should take about 10 min so that the temperature equilibrium between the shell and the water app
43、roximates that attained when performing a test. The final amount of water is then gently poured in until the level is about halfway up the neck. Any air bubbles caught against the dome that cannot be released by jarring or by swirling the water may be “pricked” or pushed to the surface with a bent w
44、ire or other suitable device. Insert the vented stopper using only enough force to just seat the stopper and immediately wipe the excess water off the top. 8.3.2. For the models with a quick-disconnect vacuum line and unlatched lid, the filling procedure is as follows: With the inlet valve closed, a
45、pply a vacuum of about 30 kPa (225 mmHg). Open the inlet valve slowly letting water in until the level reaches 25 mm (1 in.) below the top of the dome and close the valve. Continue applying vacuum and release the bubbles by jarring and rapping the vessel with a rubber mallet. Slowly open the inlet v
46、alve and allow more water in until the water overflows into the aspirator (vacuum) line and then close the valve. This vacuum application and bubble release procedure should take about 10 min so that the temperature equilibrium between the shell and the water approximates that attained when performi
47、ng a test. Disconnect the vacuum line by pulling it out at the quick-disconnect joint below the gauge. 8.3.3. Wipe the outside of the pycnometer dry, determine the mass of the full pycnometer, and measure the water temperature. Mass in GramsMass of Pycnometer Filled with Water, g16,220 16,230 16,240
48、 16,250 16,260 16,270 16,280 16,290 16,300 16,310 16,320 16,330 16,340 16,350 16,360152025303540455055606570Temperature ofWater, C 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2c T 209-7 AASHTO Not
49、e 5The shape of the standardization curve is a function of two opposing factors that can be rationally defined. As the temperature is increased, the container itself expands (adding mass“Pycnometer” line in Figure 4) and the density of the contained water decreases (resulting in loss of mass“Water” line in Figure 4). These relationships are shown in Figure 4 for a typical large-size pycnometer. The “Water” curve may be constructed by multiplying the volume at 25C (77F) by the differ
