1、Standard Method of Test for Specific Gravity or API Gravity of Liquid Asphalts by Hydrometer Method AASHTO Designation: T 295-13 ASTM Designation: D3142/D3142M-11 American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-2a
2、T 295-1 AASHTO Standard Method of Test for Specific Gravity or API Gravity of Liquid Asphalts by Hydrometer Method AASHTO Designation: T 295-13 ASTM Designation: D3142/D3142M-11 1. SCOPE 1.1. This test method covers the determination of the density of cutback asphalts using a glass hydrometer. It is
3、 applicable to cutback asphalts that are liquid at room temperature (Note 1). It provides more explicit testing procedures than those in ASTM D1298. Note 1For materials that are solid or semisolid at room temperature, use T 228 or ASTM D3289. 1.2. The values in SI units are to be regarded as the sta
4、ndard. 1.3. This standard does not purport to address all of the safety concerns 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. Specific precau
5、tionary statements are given in Section 7. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: R 66, Sampling Asphalt Materials T 228, Specific Gravity of Semi-Solid Asphalt Materials 2.2. ASTM Standards: C670, Standard Practice for Preparing Precision and Bias Statements for Test Methods for Constructio
6、n Materials D1250, Standard Guide for Use of the Petroleum Measurement Tables D1298, Standard Test Method for Density, Relative Density, or API Gravity of Crude Petroleum and Liquid Petroleum Products by Hydrometer Method D3289, Standard Test Method for Density of Semi-Solid and Solid Bituminous Mat
7、erials (Nickel Crucible Method) D4311/D4311M, Standard Practice for Determining Asphalt Volume Correction to a Base Temperature E1, Standard Specification for ASTM Liquid-in-Glass Thermometers E100, Standard Specification for ASTM Hydrometers 2015 by the American Association of State Highway and Tra
8、nsportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2a T 295-2 AASHTO 3. TERMINOLOGY 3.1. Definitions: 3.1.1. API gravitya function of specific gravity (SG) 15.6/15.6C, represented by the following equation: API = (141.5/SG 15.6/15.6C) 131.5 3.1.2. densitythe m
9、ass per unit volume of a material. 3.1.3. observed valuesvalues observed at temperatures other than the standard reference temperature. Values observed at other temperatures are hydrometer readings only and not density, relative density (specific gravity), or API gravity. 3.1.4. relative densitythe
10、ratio of the mass of a given volume of a material to the mass of the same volume of water at the same temperature. 3.1.5. specific gravityrelative density. 4. SUMMARY OF TEST METHOD 4.1. The sample is brought to the testing temperature and transferred to a cylinder at approximately the same temperat
11、ure. The cylinder and its contents are placed in a constant-temperature bath to avoid excessive temperature variation during the test. The appropriate hydrometer is lowered into the sample and allowed to settle. After temperature equilibrium is achieved, the hydrometer is read, and the temperature o
12、f the sample is noted. The hydrometer reading is converted to the density at 15C (60F) using standard tables. 5. SIGNIFICANCE AND USE 5.1. Values of density are used for converting volumes to units of mass and for correcting measured volumes from the temperature of measurement to a standard temperat
13、ure using ASTM D4311/D4311M. 6. APPARATUS 6.1. Hydrometersglass, graduated in units of specific gravity and accurate to 0.001, API gravity and accurate to 0.1 API, or density and accurate to 0.5 kg/m3(0.03 lb/ft3), conforming to Table 1. Table 1Recommended Hydrometers Hydrometer Total Length, Body D
14、iameter, Designation Measurement Range mm mm 1H to 4H API gravity 1 to 41API 325 to 335 23 to 27 21H to 28H API gravity 0 to 41API 158 to 168 12 to 15 85H to 90H Relative density (SG) 15.6/15.6C (60F) 0.8 to 1.1 325 to 335 23 to 27 105H to 108H Relative density (SG) 15.6/15.6C (60F) 0.8 to 1.0 250 t
15、o 270 20 to 24 315H to 320H Density at 15C (60F) 800 to 1100 kg/m3 (5069 lb/ft3) 325 to 335 21 to 27 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2a T 295-3 AASHTO 6.2. Other hydrometers conforming
16、 to the performance and accuracy requirements of ASTM E100 may be used. 6.3. Thermometric Deviceaccurate to 0.1C (0.2F). An ASTM 12C thermometer as defined in ASTM E1 is suitable. Any other thermometric device of equal accuracy may be used. 6.4. Hydrometer Cylinderclear glass, plastic (Note 2), or m
17、etal. For convenience in pouring, the cylinder may have a lip on the rim. The inside diameter of the cylinder shall be at least 20 mm (3/4in.) greater than the outside diameter of the hydrometer used in it. The height of the cylinder shall be such that the hydrometer floats in the sample with at lea
18、st 25 mm (1 in.) clearance between the bottom of the hydrometer and the bottom of the cylinder. Note 2Hydrometer cylinders constructed of plastic materials shall be resistant to discoloration by oil samples and must not become opaque by prolonged exposure to sunlight or oil samples. 6.5. Constant-Te
19、mperature Bathcapable of maintaining the testing temperature within 0.5C (1.0F) and of such dimensions that the level of the liquid is approximately the same as that of the sample in the hydrometer cylinder. 6.5.1. Thermometric Devicea thermometer or electronic temperature-measuring device accurate
20、to 0.25C (0.5F) shall be used to measure the temperature of the constant-temperature bath. 6.6. Ovenfor preheating the sample, and capable of maintaining the selected testing temperature within 3C (5F). 6.6.1. Thermometric Devicea thermometer or electronic temperature measuring device accurate to 1C
21、 (2F) shall be used to measure the temperature of the oven. 7. HAZARDS 7.1. Materials tested using this procedure may contain volatile and flammable hydrocarbons. Heat the sample in a covered container to minimize the loss of volatile components. Perform the test in a well-ventilated area, and avoid
22、 breathing any vapors that may be generated. Keep sources of ignition away from materials being tested. 8. SAMPLING 8.1. Take samples in accordance with AASHTO R 66. The sample shall be free of foreign substances. 8.2. Thoroughly mix the sample before removing a representative portion for testing. 9
23、. TEMPERATURE OF TEST 9.1. Because of differences in viscosity between various grades of liquid asphalts, the temperature of the test must be adjusted so that it will provide sufficient fluidity to conduct the test over a reasonable period of time. The recommended testing temperatures for the variou
24、s grades shown in Table 2 are based on a viscosity of approximately 200 to 500 cSt. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2a T 295-4 AASHTO Table 2Recommended Testing Temperatures for Variou
25、s Grades of Liquid Asphalts Grade Testing Temperature, C (F) MC-30 Room SC-70, MC-70, RC-70 40 (104) SC-250, MC-250, RC-250 60 (140) SC-800, MC-800, RC-800 80 (176) SC-3000, MC-3000, RC-3000 100 (212) 9.2. When the hydrometer value is used to select multipliers for correcting volumes to standard tem
26、peratures, the hydrometer reading should be made preferably at a temperature within 3C (5F) of the temperature at which the bulk volume of the oil was measured (Note 3). However, in cases when appreciable amounts of light fractions may be lost during determination at the bulk asphalt temperature, th
27、e temperatures given in Table 2 should not be exceeded. Note 3Volume and density correction tables are based on an average coefficient of expansion for a number of typical materials. Because the same coefficients were used in computing both sets of tables, corrections made over the same temperature
28、interval minimize errors arising from possible differences between the coefficients of the material under test and the standard coefficients. This effect becomes more important as temperatures diverge significantly from 15C (60F). 10. PROCEDURE 10.1. Select the test temperature in accordance with Se
29、ction 9. Heat the sample in an oven to 3C (5F) of the test temperature. The container shall be covered with a loose-fitting cover to prevent solvent evaporation. Bring the hydrometer cylinder and thermometer to approximately the same temperature as the sample to be tested. 10.2. Transfer the sample
30、to a clean hydrometer cylinder (Note 4) without splashing to avoid the formation of air bubbles and reduce to a minimum the evaporation of the lower boiling constituents of the more volatile samples. Remove any air bubbles formed, after they have collected on the surface of the sample, by touching t
31、hem with a piece of clean filter paper before inserting the hydrometer. Note 4When metal cylinders are used, accurate reading of the hydrometer can only be ensured if the level of the sample is within 5 mm (0.2 in.) of the top of the cylinder. 10.3. Place the cylinder containing the sample in the co
32、nstant-temperature bath previously heated to the test temperature 0.5C (1.0F). Allow sufficient time for the sample to reach the bath temperature, and verify its temperature with the thermometer, ensuring that the mercury thread is fully immersed. If a thermohydrometer is used, it may be lowered int
33、o the sample at this point instead of the thermometer. As soon as a steady thermometer reading is obtained, record the temperature of the sample to the nearest 0.2C (0.5F). 10.4. Lower the hydrometer gently into the sample. Avoid wetting the stem above the level to which it will be immersed in the l
34、iquid. Allow sufficient time for the hydrometer to become completely stationary and for all air bubbles to come to the surface. This step is particularly necessary in the case of more viscous samples. 10.5. When the hydrometer has come to rest, floating freely away from the walls of the cylinder, re
35、ad the hydrometer to the nearest scale division. Take the reading by observing, with the eye slightly above the plane of the surface of the liquid, the point on the hydrometer scale to which the sample 2015 by the American Association of State Highway and Transportation Officials.All rights reserved
36、. Duplication is a violation of applicable law.TS-2a T 295-5 AASHTO rises. This reading, at the top of the meniscus, requires correction, because hydrometers are standardized to be read at the principal surface of the liquid. The corrections for the particular hydrometer in use may be determined by
37、observing the maximum height above the principal surface of the liquid to which oil rises on the hydrometer scale when the hydrometer in question is immersed in a transparent oil having a surface tension similar to that of the sample under test. For routine work, determine the height of the meniscus
38、 by sighting across the principal surface of the liquid and estimating the rise of the meniscus on the hydrometer scale. 10.6. Immediately after observing the hydrometer scale value, cautiously stir the sample with the thermometer, keeping the mercury thread fully immersed. Record the temperature of
39、 the sample to the nearest 0.2C (0.5F) (Note 5). Should this temperature differ from the previous reading by more than 0.5C (1.0F), repeat the hydrometer and thermometer observations until the temperature becomes stable within 0.5C (1.0F). Note 5After use at a temperature higher than 37.8C (100F), a
40、llow all hydrometers of the “lead shot-in-wax” type to drain and cool in a vertical position. 11. CALCULATION 11.1. Apply any relevant corrections to the observed thermometer reading (for the scale and bulb) and to the hydrometer reading (for the scale). Make the appropriate correction to the observ
41、ed hydrometer reading. Record the corrected hydrometer reading to the nearest 0.1API, 0.001 relative density (specific gravity), or 1 kg/m3 (0.1 lb/ft3). After application of any relevant corrections, record the mean temperature values observed immediately before and after the final hydrometer readi
42、ng to the nearest 0.5C (1.0F). 11.2. To convert the observed hydrometer reading to density at 15C (60F), use the following tables from ASTM D1250, Guide for Use of the Petroleum Measurement Tables: 11.2.1. When an API gravity hydrometer has been used, use Table 5A to convert the hydrometer reading t
43、o the API gravity. Then use Table 3 to obtain the density at 15C (60F). 11.2.2. When a relative density (specific gravity) hydrometer has been used, use Table 23A to convert the hydrometer reading to the relative density 15.6/15.6C (60F). Then use Table 21 to obtain the density at 15C (60F). 11.2.3.
44、 When a density-scaled hydrometer has been used, use Table 53A to obtain the density at 15C (60F). 12. REPORT 12.1. Report the density at 15C (60F) to the nearest 1 kg/m3(0.1 lb/ft3). 13. PRECISION AND BIAS 13.1. Single-Operator PrecisionThe single-operator standard deviation for the relative densit
45、y of cutback asphalts has been found to be 0.00195. Therefore, results of two properly conducted tests by the same operator on the same material should not differ by more than 5.5 kg/m3(0.3 lb/ft3). 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. D
46、uplication is a violation of applicable law.TS-2a T 295-6 AASHTO 13.2. Multilaboratory PrecisionThe multilaboratory standard deviation for the relative density of cutback asphalts has been found to be 0.00276. Therefore, results of two properly conducted tests by two laboratories on samples of the s
47、ame material should not differ by more than 7.8 kg/m3(0.5 lb/ft3). Note 6These numbers represent the 1s and d2s limits as described in ASTM C670. 13.3. BiasThe bias of this test method has not been determined. 14. KEYWORDS 14.1. API gravity; cutback asphalt; density; hydrometer; liquid asphalt; relative density; specific gravity. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.
