1、Standard Method of Test for Determination of Draindown Characteristics in Uncompacted Asphalt Mixtures AASHTO Designation: T 305-14 American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-2c T 305-1 AASHTO Standard Method
2、of Test for Determination of Draindown Characteristics in Uncompacted Asphalt Mixtures AASHTO Designation: T 305-14 1. SCOPE 1.1. This test method covers the determination of the amount of draindown material in an uncompacted asphalt mixture sample when the sample is held at elevated temperatures co
3、mparable to those encountered during the production, storage, transport, and placement of the mixture. The test is particularly applicable to mixtures such as porous asphalt (open-graded friction course) and Stone Matrix Asphalt (SMA). 1.2. The values stated in SI units are to be regarded as the sta
4、ndard. 1.3. This standard may involve hazardous materials, operations, and equipment. 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
5、 the applicability of regulatory limitations prior to use. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standards: M 92, Wire-Cloth Sieves for Testing Purposes R 47, Reducing Samples of Hot Mix Asphalt (HMA) to Testing Size T 245, Resistance to Plastic Flow of Asphalt Mixtures Using Marshall Apparatus T 255,
6、 Total Evaporable Moisture Content of Aggregate by Drying 3. TERMINOLOGY 3.1. Definitions: 3.1.1. draindown materialFor the purpose of this test method, draindown material is considered to be that portion of material that separates itself from the sample as a whole and is deposited outside the wire
7、basket during the test. The draindown material may be composed of either asphalt binder or a combination of asphalt binder and fine aggregate. 3.1.2. draindownThe process by which draindown material separates itself from the sample as a whole. 4. SUMMARY OF METHOD 4.1. A sample of the asphalt mixtur
8、e to be tested is prepared in the laboratory or obtained from field production. The sample is placed in a wire basket, which is positioned on a plate or other suitable container of known mass. The sample, basket, and plate or container are placed in a forced-draft 2015 by the American Association of
9、 State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2c T 305-2 AASHTO oven for 1 h at a preselected temperature. At the end of 1 h, the basket containing the sample is removed from the oven, along with the plate or container and the mass o
10、f the plate or container is determined. The amount of draindown material is then calculated. 5. SIGNIFICANCE AND USE 5.1. This test method can be used to determine whether the amount of draindown material measured for a given asphalt mixture is within acceptable levels. The test provides an evaluati
11、on of the draindown potential of an asphalt mixture during mixture design or during field production. This test is primarily used for mixtures with high coarse aggregate content such as porous asphalt (open-graded friction course) and SMA. 6. APPARATUS 6.1. Forced-Draft OvenCapable of maintaining th
12、e temperature in a range from 120 to 175C (250 to 350F). The oven should maintain the set temperature to within 2C (3.6F). 6.2. PlatesOr other suitable containers of appropriate size. The plates or containers used should be of appropriate durability to withstand the oven temperatures. Cake pans or p
13、ie tins are examples of suitable types of containers. 6.3. Standard BasketMeeting the dimensions shown in Figure 1. The basket shall be constructed using standard 6.3-mm (0.25-in.) sieve cloth as specified in M 92. 6.4. BalanceAccurate to 0.1 g. 6.5. Other apparatusSpatulas, trowels, bowls, and mixe
14、r as needed. 7. SAMPLE PREPARATION 7.1. Laboratory-Prepared Samples: 7.1.1. Number of SamplesFor each mixture tested, the draindown characteristics should be determined at two different temperatures. The two temperatures should be the anticipated plant production temperature, as well as 15C (27F) ab
15、ove that temperature (Note 1). For each temperature, duplicate samples should be tested. Thus for one asphalt mixture, a minimum of four samples will be tested. Note 1When using the test as part of the mixture design procedure, the test should be performed at two temperatures in order to determine t
16、he potential effect that plant temperature variation may have on the mixture during production. When the test is used in the field during production, it should be necessary to perform the test at the plant production temperature only. 7.1.2. Dry the aggregate to a constant mass in accordance with T
17、255, and sieve it into the appropriate size fractions as indicated in T 245. 7.1.3. Determine the anticipated plant production temperature or select a mixing temperature in accordance with T 245. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Dupl
18、ication is a violation of applicable law.TS-2c T 305-3 AASHTO 7.1.4. Place into separate pans for each test sample the amount of each size fraction required to produce completed mixture samples having a mass of 1200 200 g. The aggregate fractions shall be combined such that the resulting aggregate b
19、lend has the same gradation as the job mix formula. Place the aggregate samples in an oven and heat them to a temperature not to exceed the mixing temperature established in Section 7.1.3 by more than approximately 28C (50F). 7.1.5. Heat the asphalt binder to the temperature established in Section 7
20、.1.3. Figure 1Wire Basket Assembly 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2c T 305-4 AASHTO 7.1.6. Place the heated aggregate in the mixing bowl. Add any stabilizers (Note 2) and thoroughly m
21、ix the dry components. Form a crater in the aggregate blend and add the required amount of asphalt binder. The amount of asphalt binder shall be such that the final sample has the same asphalt content as the job mix formula. At this point, the temperature of the aggregate and asphalt binder shall be
22、 within the limits of the mixing temperature established in Section 7.1.3. Using a spatula (if mixing by hand) or a mixer, mix the aggregate (and stabilizer, if any) and asphalt binder quickly until the aggregate is thoroughly coated. Note 2Some types of stabilizers, such as fibers or some polymers,
23、 must be added directly to the aggregate prior to mixing with the asphalt binder. Other types of stabilizers must be added directly to the asphalt binder prior to blending with the aggregate. 7.2. Plant-Produced Samples: 7.2.1. Number of SamplesFor plant-produced samples, duplicate samples should be
24、 tested at the plant production temperature. 7.2.2. Samples may be obtained during plant production by sampling the mixture at any appropriate location, such as the trucks prior to the mixture leaving the plant. Samples obtained during actual production should be reduced to the proper test sample si
25、ze by R 47. Note 3Caution should be exercised when sampling from surge or storage bins because draindown may already have taken place. 8. PROCEDURE 8.1. Transfer the hot laboratory-produced or plant-produced uncompacted mixture sample to a tared wire basket as described in Section 6.3. Place the ent
26、ire sample in the wire basket. Do not consolidate or otherwise disturb the sample after transferring it to the basket. Determine the mass of the sample to the nearest 0.1 g. Care should be exercised to ensure that the sample does not cool more than 25C (77F) below the test temperature. (See Section
27、8.2.) 8.2. Determine and record the mass of a plate or other suitable container to the nearest 0.1 g. Place the basket on the plate or container and place the assembly into the oven at the temperature as determined in Section 7.1.1 or 7.2.1 for 60 5 min. If the sample has cooled more than 25C (77F)
28、below the test temperature, the test should be conducted for 70 5 min. 8.3. After the sample has been in the oven for the time specified in Section 8.2, remove the basket and plate or container from the oven. Determine and record the mass of the plate or container plus draindown material to the near
29、est 0.1 g. 9. CALCULATIONS 9.1. Calculate the percent of mixture that drained by subtracting the initial plate or container mass from the final plate or container mass and dividing this value by the initial total sample mass. Multiply the result by 100 to obtain a percentage. 100 percent of mixture
30、that drained or percent draindownfitMMM= 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2c T 305-5 AASHTO where: Mf= final plate or container mass; Mi= initial plate or container mass; and Mt= initial total sample mass. 10. REPORT 10.1. Report the average percent draindown (average percent of mixture that drained) at each of the test temperatures. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.
