1、Standard Method of Test for Determining Degree of Particle Coating of Asphalt Mixtures AASHTO Designation: T 195-18 Technical Section: 2c, AsphaltAggregate Mixtures Release: Group 3 (August) ASTM Designation: D2489/D2489M-16 American Association of State Highway and Transportation Officials 444 Nort
2、h Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-2c T 195-1 AASHTO Standard Method of Test for Determining Degree of Particle Coating of Asphalt Mixtures AASHTO Designation: T 195-18 Technical Section: 2c, AsphaltAggregate Mixtures Release: Group 3 (August) ASTM Designation: D2489/D2489M-1
3、6 1. SCOPE 1.1. This method covers the determination of the degree of particle coating in an asphalt mix on the basis of the percentage of coarse aggregate particles that are completely coated. Determination of the percentage of coated particles for varying mixing times may be used to establish the
4、least mixing time required to produce satisfactory coating of the aggregate for a given set of conditions. This test method applies to mixtures containing aggregate of a nominal maximum aggregate size less than 38 mm (11/2in.). 1.2. The values stated in SI units are to be regarded as the standard. 2
5、. REFERENCED DOCUMENTS 2.1. AASHTO Standards: M 156, Requirements for Mixing Plants for Hot-Mixed, Hot-Laid Bituminous Paving Mixtures T 168, Sampling Bituminous Paving Mixtures 2.2. ASTM Standard: E11, Standard Specification for Woven Wire Test Sieve Cloth and Test Sieves 3. APPARATUS 3.1. Sieves9.
6、5-mm (3/8-in.) and 4.75-mm (No. 4) sieves conforming to ASTM E11. 3.2. StopwatchFor checking the actual mixing time. 3.3. ThermometerWith a range from 10 to 204.4C (50 to 400F). 3.4. Sample Shovel. 3.5. Sample Trays. 2018 by the American Association of State Highway and Transportation Officials. All
7、 rights reserved. Duplication is a violation of applicable law.TS-2c T 195-2 AASHTO 4. SAMPLING 4.1. Batch Plant, as defined in M 156Permit the plant to operate at an established mixing time per batch (timed by a stopwatch). 4.2. Continuous Mix Plant, as defined in M 156Establish a mixing time by us
8、e of the following formula: ( )plant contents, kg lbkg lbplant output,ss(1) 4.3. Drum Mix Plant, as defined in M 156Operate the plant at a steady state condition for a period of time long enough to complete the sampling. 4.4. Samples should be taken at the asphalt mixing plant, immediately after dis
9、charge from the plant, using the most appropriate sampling location and sampling procedure according to T 168. 4.5. The amount of material required to perform the test is approximately 2.3 to 3.6 kg (5 to 8 lb). 5. PROCEDURE 5.1. Sieve each material immediately, while it is still hot, on a 9.5-mm (3
10、/8-in.) sieve for materials with a maximum size larger than 9.5 mm (3/8in.). For materials with a maximum size of 9.5 mm (3/8in.) or less, use a 4.75-mm (No. 4) sieve. Take a sample large enough to yield between 200 and 500 coarse particles retained on the 9.5-mm (3/8-in.) or 4.75-mm (No. 4) sieve.
11、Do not overload the sieves. If necessary, sieve the sample in two or three operations. Shaking should be reduced to a minimum to prevent recoating of uncoated particles. 5.2. Place the particles on a clean surface in a one-particle layer, and start counting them immediately. 5.3. Very carefully exam
12、ine each particle under direct sunlight, fluorescent light, or similar light conditions. If even a tiny speck of uncoated stone is noted, classify the particle as “partially uncoated.” If completely coated, classify the particle as “completely coated.” 6. CALCULATION 6.1. The required computation is
13、 as follows: no. of completely coated particles 100percent of coated particlestotal no. of particles= (2) 7. REPORT 7.1. Report the following information: 7.1.1. Type of plantbatch, continuous mix, or drum mix; 7.1.2. Type of mix; 7.1.3. Mixing time to the nearest 1 s, if applicable; 2018 by the Ame
14、rican Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.TS-2c T 195-3 AASHTO 7.1.4. Mixing temperature to the nearest 5C (9F); and 7.1.5. Percent of coated particles to the nearest 0.1 percent. 8. PRECISION AND BIAS 8.1. Prec
15、isionNo precision data are available at this time. As the test is intended to be performed as soon after mixing as possible, there is a concern that remixing due to shipping samples will change the coating of the aggregates. 8.2. BiasBecause there are no accepted reference materials suitable for det
16、ermining the bias of this test method, no statement of bias is presented. 9. KEYWORDS 9.1. Asphalt; asphalt mixing plant; coating; mixing time; pug mill. 2018 by the American Association of State Highway and Transportation Officials. All rights reserved. Duplication is a violation of applicable law.
