1、Standard Method of Test for Specific Gravity and Absorption of Aggregate by Volumetric Immersion Method AASHTO Designation: T 354-171Technical Section: 1c, Aggregates Release: Group 3 (August 2017) American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suit
2、e 249 Washington, D.C. 20001 TS-1c T 354-1 AASHTO Standard Method of Test for Specific Gravity and Absorption of Aggregate by Volumetric Immersion Method AASHTO Designation: T 354-171Technical Section: 1c, Aggregates Release: Group 3 (August 2017) 1. SCOPE 1.1. This method covers the determination o
3、f bulk and apparent specific gravity and absorption of fine and coarse aggregate at 20 1C (70 2F) for dry and saturated aggregates. 1.2. This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns associated with its
4、use. It is the responsibility of the user of this procedure to consult and establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to its use. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: M 231, Weighing Devices Used in the Testing of Ma
5、terials R 76, Reducing Samples of Aggregate to Testing Size T 2, Sampling of Aggregates T 19M/T 19, Bulk Density (“Unit Weight”) and Voids in Aggregate T 84, Specific Gravity and Absorption of Fine Aggregate T 85, Specific Gravity and Absorption of Coarse Aggregate T 255, Total Evaporable Moisture C
6、ontent of Aggregate by Drying 3. SIGNIFICANCE AND USE 3.1. Bulk specific gravity is the characteristic generally used for calculations of the volume occupied by the aggregate in various mixtures containing aggregate including portland cement concrete (PCC), bituminous concrete, and other mixtures th
7、at are proportioned or analyzed on an absolute volume basis. Bulk specific gravity is also used in the computation of voids in aggregate in T 19M/T 19. Bulk specific gravity determined on the saturated surface-dry basis is used if the aggregate is wet, that is, if its absorption has been satisfied.
8、Conversely, the bulk specific gravity determined on the oven-dry basis is used for computations when the aggregate is dry or assumed to be dry. 3.2. Apparent specific gravity pertains to the relative density of the solid material making up the constituent particles not including the pore space withi
9、n the particles that is accessible to water. This value is not widely used in construction aggregate technology. 2017 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-1c T 354-2 AASHTO 3.3. When it is deem
10、ed that the aggregate has been in contact with water long enough to satisfy most of the absorption potential, the absorption values are used to represent the change in the mass of an aggregate due to water absorbed into the pore spaces within the constituent particles, compared to the dry condition.
11、 The laboratory standard for absorption is that obtained after submerging dry aggregate for approximately 15 h in water. Aggregates mined from below the water table may have a higher absorption when used, if not allowed to dry. Conversely, some aggregates when used may contain an amount of absorbed
12、moisture less than the 15-h soaked condition. For an aggregate that has been in contact with water and that has free moisture on the particle surfaces, the percentage of free moisture can be determined by deducting the absorption from the total moisture content determined by T 255 drying. 3.4. Users
13、 of this method are encouraged to be cautious in applying the results. Unadjusted values achieved for specific gravity and absorption can be significantly different from those achieved from T 84 and T 85. Results from this method will affect the calculated results for volumetrics in hot mix asphalt
14、(HMA) and absorption in PCC. When using the results from this test for pay factor and/or compliance purposes, the user is required to adjust the absorption and specific gravity values in accordance with Section 13. A graphical method and source/aggregate specific correlation method are shown in Anne
15、x B that can be used to correlate results to T84 and T85. 4. APPARATUS 4.1. Flask with Plug for Coarse AggregateA glass flask with a bulb volume of 3000 to 4000 mL and a separate plug. The neck of the flask shall be marked with 5 mL graduated increments that correspond to a precision of at least 0.1
16、 percent of the sample volume. Overall length of the flask is approximately 760 mm (30 in.) (see Note 1 and Figure 1). 4.2. Flask for Fine AggregateA glass flask with a bulb volume of 2000 mL. The neck of the flask shall be marked with 1 mL graduated increments that correspond to a precision of at l
17、east 0.1 percent of the sample volume. Overall length of the flask is approximately 760 mm (30 in.) (see Note 1 and Figure 1). Note 1The flask to be used for fine aggregate will have a neck approximately 25 mm (1 in.) in diameter. The flask used for coarse aggregate will have a neck approximately 51
18、 mm (2 in.) in diameter. Figure 1Typical Flask 2017 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-1c T 354-3 AASHTO 4.3. Scale with a capacity of at least 10 000 gThe scale shall comply with the require
19、ments in M 231. 4.4. Minimum 450-mm (18-in.) long rod with dry, absorbent swab. 4.5. Timer that can be read to the nearest second, and that can measure elapsed time up to 24 h. 5. CALIBRATION OF FLASK 5.1. Determine and record the empty weight of the flask, to the nearest gram. 5.2. Fill flask with
20、distilled water at 20 1C (70.0 2F) such that the bottom of the meniscus is exactly even with the zero mark. Note 2If a flask does not have a zero mark, add water to the first major graduation (10 mL mark on a fine aggregate flask); then subtract that amount from the calibrated flask volume in Equati
21、on 1. 5.3. Determine and record the weight of the filled flask to the nearest gram. 5.4. Determine the calibrated volume of the flask as follows: Vcal= B A (1) where: Vcal= calibrated volume of the flask, mL; A = weight of empty flask, g; and B = weight of flask filled with water, g. Note 3Due to th
22、e definition of a milliliter and a gram (1 milliliter of water weighs 1 gram), these values can be interchanged without conversions. 6. SAMPLING 6.1. Sampling of aggregate shall be accomplished in accordance with T 2. 7. PREPARATION OF TEST SPECIMEN 7.1. Obtain approximately 2 kg of fine aggregate o
23、r 3 kg of coarse aggregate using the applicable procedures described in R 76. 7.2. Dry the sample in an oven or a suitable pan or vessel to constant mass at a temperature of 110 5C (230 9F). Allow it to cool to comfortable handling temperature, without allowing it to re-absorb any water from the sur
24、rounding environment. This can be accomplished by covering the container with a plate or cover that blocks direct access of the ambient humid air to the cooling sample. 8. TEST PROCEDURE 8.1. Weigh out 1200 10 g of oven-dry fine aggregate or 2500 50 g of oven-dry coarse aggregate to be tested. If te
25、sting lightweight aggregate, reduce the amount of material to 600 10 g for fine aggregate, or 900 g 10 g for coarse aggregate. 8.2. The actual weight, Wd, of oven dry aggregate should be recorded to the nearest 0.01 grams. 2017 by the American Association of State Highway and Transportation Official
26、s. All rights reserved. Duplication is a violation of applicable law.TS-1c T 354-4 AASHTO 8.3. Fill the bottom portion of the flask approximately one half full, by height, with 20 1C (70 2F) distilled water (see Note 4). 8.4. Measure out, but do not add, approximately 250 g of 20 1C (70 2F) distille
27、d water. Note 4The volume of water in Sections 8.3 and 8.4 may need to be adjusted for the individual flask being used. It is important that during the filling process, the combined initial volume of water and the dry aggregate not plug the neck of the flask. Therefore, the following procedure is in
28、tended to allow sufficient water for the aggregate to become completely submerged, but to not rise into the narrow neck of the flask. 8.5. Dry the inside of the neck of the flask with a dry absorbent swab. Note 5If the inside of the neck is not completely dry, finer portions of the sample may adhere
29、 to the moisture, plugging the neck of the flask as the sample is added. 8.6. Pour the aggregate sample into the flask as quickly as possible, without plugging the neck. Note 6It is recommended that an outside funnel not be used. The sand has a tendency to plug the smaller hole of the funnel, wherea
30、s it typically pours through the built-in funnel without plugging. 8.7. Start the timer immediately when the aggregate first hits the water in the flask. 8.8. After all of the sample has been poured into the flask, immediately add enough of the holdback water measured out in Section 8.4 to raise the
31、 water level sufficiently up into the graduated portion of the neck of the flask, so that the water level does not drop below the graduated portion during the duration of the test. 8.9. Do not shake, agitate, or otherwise disturb the flask at this time. 8.10. Take the reading of the initial water le
32、vel, Ri, in the neck of the flask 30 s after the first particle has entered the water. 8.11. Determine and record the weight of the flask filled with aggregate and water, WT, to 0.1 grams. 8.12. Place a plug into the neck of the flask, then aggressively shake, roll, and otherwise agitate the flask i
33、n order to remove all of the released air. Prevent loss of water during the shaking and agitation of the flask. Stop shaking and agitating the flask when the timer shows 3 min. 8.13. Allow the flask to remain undisturbed for at least 2 min or longer until all the released air bubbles have escaped fr
34、om the flask. 8.14. Obtain and record the reading of the water level in the neck of the flask at 5 min elapsed time (from when the aggregate first hits the water). Record the time the water level reading is actually made. 8.15. It is recommended that water level readings be taken at 10 min, 30 min,
35、60 min, 2 h, and 4 h elapsed time (see Note 7). Make sure to agitate all of the air out of the sample, and allow the flask to settle for at least 2 min or until all the released air bubbles have escaped from the flask before taking each water level reading. Record the time when each water level read
36、ing is made. See Annex A. Note 7It is not critical that the readings are taken at the exact times shown. 8.16. Take the final water level reading, Rfinal, at 25 1 h. It is extremely important that all air released during the soak period be completely eliminated from the flask before taking the final
37、 reading. Make sure that the flask has been thoroughly and completely shaken and agitated, and then left 2017 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-1c T 354-5 AASHTO undisturbed to allow all of
38、the air to escape from the flask until there is no air left in the system. Make sure that the air removal process is started early enough to completely eliminate all of the air within the designated time. 9. ABSORPTION 9.1. Calculate the absorption as follows: absorption, (%) 100absdWW= (2) where: W
39、abs= water absorbed into the sample, (Ri Rfinal), mL, where Ri= initial water level reading, mL; and Rfinal= final water level reading, mL; and Wd= original dry weight of sample, g. 10. SATURATED BULK SPECIFIC GRAVITY (Ss) 10.1. Calculate the saturated bulk specific gravity as follows: ( )( )d abssi
40、wWWSVV+=(3) where: Wd= original dry weight of sample, g; Wabs= water absorbed into the sample, mL; Vi= initial volume, (Ri+ Vcal), mL, where Vcal= calibrated flask volume, mL; and Vw= volume of test water WT (Wd+ Wf), mL, where WT= total weight of flask, water, and sample, g; and Wf= weight of flask
41、, g. 11. DRY BULK SPECIFIC GRAVITY (Sd) 11.1. Calculate the dry bulk specific gravity as follows: ( )ddiwWSVV=(4) 12. APPARENT DRY SPECIFIC GRAVITY (Sa) 12.1. Calculate the apparent dry specific gravity as follows: ( ) ( )finaldad f calWSW W V WT R=+ (5) 2017 by the American Association of State Hig
42、hway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-1c T 354-6 AASHTO 13. CONVENTIONAL ABSORPTION AND SPECIFIC GRAVITIES The results from this standard can be used for many different applications. However, the direct results for absorption may diff
43、er substantially from those achieved from T 84 or T 85. Consequently, if the results from these tests are to be used in the development, maintenance, pay-factor determination, or evaluation of portland cement, concrete, or asphalt mixtures, they must be empirically adjusted in accordance with Annex
44、B to provide equivalent results. 14. REPORT 14.1. Report the specific gravity results to the nearest 0.001, and indicate the type of specific gravity, whether bulk (dry), bulk (saturated surface-dry), or apparent. 14.2. Report the direct absorption result obtained from the direct readings to the nea
45、rest 0.1 percent. If the results are to be adjusted as described in the Annexes, designate the procedure used, the adjusted values, and the adjusted characteristics. 15. KEYWORDS 15.1. Absorption; aggregate; phunque absorption; specific gravity. ANNEX A (Mandatory Information) A1. INTERMEDIATE WATER
46、 LEVEL READINGS A1.1. This test provides an internal quality process check. By plotting the intermediate readings against time on a logarithmic scale, an approximately straight line should be determined. If the line is not essentially straight, then something happened during the performance of the t
47、est. A1.2. It also provides the ability to determine the time-rate of absorption relationship for a particular material. Once the time-rate of absorption plot has been established, it can then be used in the field. If intermediate levels of absorption are to be acknowledged during the delivery and c
48、onstruction procedures using this aggregate, the starting and anticipated ending points and their relative degree of saturation can be taken directly from the resulting plot. A1.3. A typical plot is shown in Figure A1.1. 2017 by the American Association of State Highway and Transportation Officials.
49、 All rights reserved. Duplication is a violation of applicable law.TS-1c T 354-7 AASHTO Figure A1.1Phunque Absorption Test A1.4. Plot the readings on semilog paper with the x-axis being time on the logarithmic scale. A1.5. Example Data: A typical datasheet that has been found to work well with this procedure is shown in Figure A1.2. A1.5.1.2380.02382.02384.02386.02388.02390.02392.02394.00.1 1 10 100 1000 10000Time (Minutes)Volume(ml) 2017 by the American Association of State Highway and Transporta
