1、Standard Method of Test for Compressive Strength of Hot Mix Asphalt AASHTO Designation: T 167-10 (2015) American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-2d T 167-1 AASHTO Standard Method of Test for Compressive Stre
2、ngth of Hot Mix Asphalt AASHTO Designation: T 167-10 (2015) 1. SCOPE 1.1. This test method provides a method for measuring the compressive strength of compacted asphalt mixtures. It is for use with specimens weighed, batched, mixed, and fabricated in the laboratory, as well as for mixtures manufactu
3、red in a hot mix plant. 1.2. The values stated in SI units are to be regarded as the standard. The values given in parentheses are provided for information only. 1.3. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of th
4、e user of this standard to 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 T 2, Sampling of Aggregates T 27, Sieve Analysi
5、s of Fine and Coarse Aggregates R 66, Sampling Asphalt Materials T 166, Bulk Specific Gravity (Gmb) of Compacted Hot Mix Asphalt (HMA) Using Saturated Surface-Dry Specimens T 168, Sampling Bituminous Paving Mixtures T 201, Kinematic Viscosity of Asphalts (Bitumens) T 209, Theoretical Maximum Specifi
6、c Gravity (Gmm) and Density of Hot Mix Asphalt (HMA) T 248, Reducing Samples of Aggregate to Testing Size T 269, Percent Air Voids in Compacted Dense and Open Asphalt Mixtures T 316, Viscosity Determination of Asphalt Binder Using Rotational Viscometer 2.2. ASTM Standards: C670, Standard Practice fo
7、r Preparing Precision and Bias Statements for Test Methods for Construction Materials D341, Standard Practice for Viscosity-Temperature Charts for Liquid Petroleum Products D1075, Standard Test Method for Effect of Water on Compressive Strength of Compacted Bituminous Mixtures D2493/D2493M, Standard
8、 Viscosity-Temperature Chart for Asphalts E4, Standard Practices for Force Verification of Testing Machines 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2d T 167-2 AASHTO 2.3. FHWA Standard: FP-03,
9、 Standard Specifications for Construction of Roads and Bridges on Federal Highway Projects 3. SIGNIFICANCE AND USE 3.1. The compressive strength of specimens prepared and tested by this test method along with density and voids properties are used for laboratory mix design of asphalt mixtures. 3.1.1.
10、 This test method also describes methods that can be used for molding, curing, and testing of specimens being evaluated by ASTM D1075. 3.1.2. When used in conjunction with other mixture physical properties, the compressive strength may contribute to the overall mixture characterization and is one fa
11、ctor determining its suitability for use under given loading conditions and environment as a highway paving material. 3.2. Typical values of minimum compressive strengths for design of asphalt mixtures by this test method for different traffic densities are given in Table 402-1 of the “Standard Spec
12、ifications for Construction of Roads and Bridges on Federal Highway Projects, 2003.” Some state departments of transportation and federal agencies have specific requirements of their own based on their experience with this test method. The agencies should be consulted for their specific requirements
13、 if work is to meet their standards. 3.3. Reheated field mixtures are permissible in this test method, but the resulting compressive strengths will be higher than for newly prepared mixtures due to the change in the binder viscosity, an element of the compressive strength as measured under these loa
14、ding conditions and temperature (Note 4). 4. APPARATUS 4.1. Molds and PlungersMolds and plungers shall be as follows: 4.1.1. The molding cylinder shall have sufficient height to allow fabrication of a 101.6-by-101.6-mm (4-by-4-in.) specimen. It shall have an inside diameter of 101.60 to 101.73 mm (4
15、.000 to 4.005 in.) and a nominal wall thickness of 6.4 mm (1/4in.). 4.1.2. The mold plungers shall pass through the mold freely and shall have a diameter within 1.27 mm (0.050 in.) of the molds inside diameter. The plungers may be solid, hollow, or other structure as long as the ends are at least 12
16、.7 mm (1/2in.) thick and are at a right angle to the mold wall. The bottom plunger must be within 50 4 mm (2 1/8in.) high, but the top plunger may be any suitable height. 4.1.3. Specimens Other Than 101.6 by 101.6 mm (4 by 4 in.)Molds and plungers for fabricating these size specimens may be used in
17、accordance with Section 6. 4.2. SupportsTemporary supports shall be provided to raise the molding cylinder 25.4 mm (1 in.) during the molding operation. Steel bars 25.4 mm (1 in.) square are suitable. 4.3. Testing MachineThe testing machine must be of any type of sufficient capacity that will provid
18、e a range of accurately controllable rates of vertical deformation. Because the rate of vertical deformation for the compression test is specified as 0.05 mm/minmm (0.05 in./minin.) of specimen height, and it may be necessary to test specimens ranging in size from 50.8 by 50.8 mm 2015 by the America
19、n Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2d T 167-3 AASHTO (2 by 2 in.) to perhaps 203.2 by 203.2 mm (8 by 8 in.) in order to maintain the specified minimum ratio of specimen diameter to particle size, the testin
20、g machine should have a range of controlled speeds covering at least 2.5 mm (0.1 in.)/min for 50.8-mm (2-in.) specimens to 10.2 mm (0.4 in.)/min for 203.2-mm (8-in.) specimens. The testing machine shall conform to the requirements of ASTM E4. The testing machine shall be equipped with two steel bear
21、ing blocks with hardened faces, one of which is spherically seated and the other plain. The spherically seated block shall be mounted to bear on the upper surface of the test specimen and the plain block shall rest on the platen of the testing machine to form a seat for the specimen. The bearing fac
22、es of the plates shall have a diameter slightly greater than that of the largest specimens to be tested. The bearing faces, when new, shall not depart from a true plane by more than 0.0127 mm (0.0005 in.) at any point and shall be maintained within a permissible variation limit of 0.025 mm (0.001 in
23、.). In the spherically seated block, the center of the sphere shall coincide with the center of the bearing face. The movable portion of this block shall be held closely in the spherical seat, but the design shall be such that the bearing face can be rotated freely and tilted through small angles in
24、 any direction. 4.4. OvenThe oven used in the preparation of materials or reheating of mixtures shall be controllable within 3C (5F) of any specified temperature above ambient up to 200C (392F). 4.5. Hot PlateA small hot plate equipped with a rheostat shall be provided for supplying sufficient heat
25、under the mixing bowl to maintain the aggregate and asphalt material at the desired temperature during mixing. 4.6. Hot Water Bath or OvenA water bath or oven sufficiently large to hold three sets of 101.6-mm (4-in.) molds and plungers. If the water bath does not have an internal temperature control
26、, a hot plate of sufficient capacity with a control to maintain the water bath at a temperature just under the boiling point will be required. The oven shall be capable of maintaining a temperature of 93.3 to 135C (200 to 275F). 4.7. Air BathThe air bath shall be thermostatically controlled and shal
27、l maintain the air temperature for storing the specimens at 25 0.5C (77 1.0F) immediately prior to performing the compression test. 4.8. BalanceThe balance shall have sufficient capacity, be readable to 0.1 percent of the sample mass, or better, and conform to the requirements of M 231. 4.9. Mixing
28、MachineMechanical mixing is preferable to hand mixing. Any type of mixer may be used, provided it can maintain the mixture at the required mixing temperature and will produce a well coated, homogeneous mixture of the required size in 2 min or less, and further provided that it is of such design that
29、 fouling of the blades will be minimized and each individual batch can be retrieved in essentially its entirety, including asphalt and fines. Hand mixing is allowable, if necessary, but for hot mixtures the time required to obtain satisfactory coating is often excessive, and generally the test resul
30、ts are less uniform than when machine mixing is employed. 4.10. SpatulasA flexible spatula for scraping the mixing bowl and a stiff spatula for spading the specimen in the mold. 5. PREPARATION OF TEST MIXTURES 5.1. Limit the size of the individual batches to the amount required for one test specimen
31、. 5.2. Mix an initial batch for the purpose of “buttering” the mixing bowl and stirrers. Empty this batch after mixing and clean the sides of the bowl and stirrers of mixture residue by scraping with a small limber spatula. Do not wipe with cloth or wash clean with solvent, except when a change is t
32、o be made in the asphalt binder or at the end of a run. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2d T 167-4 AASHTO 5.3. Mold a trial specimen in order to determine the correct weight of materia
33、ls to produce a specimen of the desired height. Use the initial or “buttering” batch for this purpose, if desired. 5.4. Aggregate ingredient samples shall be obtained in accordance with T 2 and reduced to the appropriate size by T 248. When preparing aggregates for batching, each reduced ingredient
34、sample shall be separated into the desired size fractions in accordance with T 27. Agency practice will specify which sieves should be used to derive the desired fractions. 5.4.1. The Mixture Design, Job Mix Formula, or other control shall be used to combine the appropriate weight of each size from
35、each ingredient aggregate to obtain the appropriate gradation and batch weight and to determine the appropriate weight of asphalt binder to use for each specimen. 5.5. A representative sample of asphalt binder shall be obtained in accordance with R 66 from a representative stock of the material. 5.5
36、.1. For unmodified asphalt binders, the temperature versus kinematic viscosity relationship for the asphalt binder involved dictates the temperature that should be used for preparing the hot mix asphalt test specimens. The mixing temperature is typically the temperature that yields 170 20 centistoke
37、s of viscosity. The compacting temperature is typically the temperature that yields 280 30 centistokes of viscosity. Mixing and compacting temperatures may be provided by the asphalt binder manufacturer (Note 1). Aggregate is heated no hotter than 28C (50F) above the mixing temperature to allow for
38、dry mixing prior to adding the asphalt binder. Note 1Modified asphalt binders may not adhere to the equiviscous ranges noted in Section 5.5.1. The user should refer to the asphalt binder manufacturer to establish appropriate mixing and compaction temperature ranges. In no case should the mixing temp
39、erature exceed 175C (350F). 5.5.2. The mixing and compacting temperatures are normally available from the asphalt binder supplier; however, it may be determined by testing the asphalt binder for kinematic viscosity (T 201) at two temperatures and plotting a graph showing the temperature and correspo
40、nding viscosity for each of the two points. Temperatures of 135C (275F) and 163C (325F) are convenient for asphalt binder grade PG 64-22; however, lower temperatures may be more appropriate for less viscous grades. 5.5.3. The graph paper may be a single or double cycle semilog paper with the log axi
41、s (y) ranging from 100 to 1000 centistokes and the linear (x) axis established to cover the above two temperatures. Greater precision is derived by selecting ranges that utilize most of the page. General descriptions of the graph paper can be observed in ASTM D2493/D2493M and ASTM D341. 5.6. Laborat
42、ory-Mixed MaterialPreheat the bowl and batch of aggregate in an oven meeting the requirements of Section 4.4 to a temperature that complies with the aggregate temperature in Section 5.5. This will result in an acceptable temperature after dry mixing. With the bowl of aggregate resting on a balance,
43、quickly pour the prescribed weight of hot asphalt binder onto the hot aggregate and immediately mix the asphalt binder into the aggregate (Section 4.9). If mixing by hand, this can be done with a large spoon by rolling the material from perimeter toward the center to maximize aggregate and asphalt c
44、ontact and minimize asphalt contact with the bowl. The mixing should be completed within 90 to 120 s, during which time the temperature should have dropped to about 3 to 5C (5 to 9F) above the compacting temperature. As soon as the material has been thoroughly mixed and has reached a temperature wit
45、hin the specified range, charge the mold and compact the specimen. Note 2If the countertop is metal, an insulator such as paper may be used to reduce the rate of cooling. 5.6.1. When mixing is complete, the temperature of the mixture must be at least 3C (5F) above the compacting temperature; otherwi
46、se, discard the mixture and repeat mixing procedures according to Section 5.6, taking precautions to maintain temperature. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.TS-2d T 167-5 AASHTO Note 3Rehea
47、ting may result in increased aging of the asphalt binder. Depending on the particular asphalt binder being tested, this can result in significantly higher strength values. Note 4Laboratory samples prepared according to this test method may produce different test results, such as compressive strength
48、 values and percent air voids, when compared to results obtained from reheated plant-mixed field samples due to the effect of additional cure time and the absorption of asphalt binder by the aggregate in the field sample. 5.7. Plant-Mixed MaterialPlant-mixed hot mix asphalt shall be sampled in accor
49、dance with T 168 and reduced to slightly more than the amount needed to fabricate the specimen. The size reduction shall be in accordance with R 47, Quartering Method. Adjust the weight of the reduced sample to the required weight by removing and discarding a small amount of the mixture. Care must be exercised to discard both fine and coarse particles to maintain the proper gradations. 5.7.1. Place the weighed sample into an appropriate container and heat in an oven to the mixing temperature provide
