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ASTM D 8259/D8259M : 2021

Current

Current

The latest, up-to-date edition.

Standard Test Method for Rotary Wheel Testing (RWT) of Compacted Asphalt Mixtures

Available format(s)

Hardcopy , PDF

Language(s)

English

Published date

08-25-2021

US$69.00
Excluding Tax where applicable

Committee
D 04
DocumentType
Test Method
Pages
12
PublisherName
American Society for Testing and Materials
Status
Current

1.1This test method describes a procedure for testing the rutting and moisture susceptibility of asphalt specimens using the Rotary Wheel Tester (RWT). Superpave Gyratory Compactor (SGC) specimens (Test Method D6925) are wrapped, conditioned, submerged in water, and confined between three metal wheels in continuous synchronized rotation with each wheel applying a fixed load around the periphery of the specimen. The system records the number of load cycles applied to the specimen, the deformation of the specimen (rut depth), the loading rate, the temperature of the water, and Sigma, which is an indication of specimen roundness.

1.2The test method is used to determine the premature rutting susceptibility of asphalt mixtures by measuring rut depth as a function of number of load cycles throughout the test.

1.3This test method also measures the potential for moisture damage effects because the specimens are submerged in temperature-controlled water during preconditioning and for the duration of the test.

1.4The parameters of the test are shown in Table 1. See an example of the test parameters used in Appendix X1.

Note 1:This test uses a typical specimen produced by a Superpave gyratory compactor.

Note 2:The ruggedness study identified air void content as the most influential factor evaluated and recommended a tolerance of ±0.25 % to minimize the effect of air void content on the test results. The precision study evaluated three asphalt mixtures with specimen air void contents ranging from 2.87 % to 3.23 %, from 4.28 % to 4.64 %, and from 5.77 % to 6.19 %. Precision statements covering the air void content ranges of 2.75 % to 4.75 % and 5.75 % to 6.25 % can be found in Section 10. Lemke and Bahia (2019) found that an asphalt mixture with 7 % air void content was more susceptible to rutting than a mixture with 3 % air void content and that the test results for the 7 % AV mixture did not differentiate between control factors such as test temperature and mixture source like the mixture with 3 % air void content did.

Note 3:The University of Wisconsin at Madison Modified Asphalt Research Center (2017) reported that the City of LA selected the test temperature of 60 °C [140 °F] because “(1) it approximates the observed high average temperature of most pavements, (2) it is close to the high temperature performance grade classification of the asphalt binder used in most local applications, (3) it allows a test to be performed in an accelerated time frame (about 2 h excluding preconditioning time), and (4) research on rut testing has shown [that] the asphalt binder seems to have the most control over the test results at lower test temperatures.” The ruggedness study was completed at 60 °C [140 °F] using PG 64-10 with 50 % RAC asphalt mixture. The precision study was completed at 60 °C [140 °F] using PG 64-10 with 50 % RAC asphalt mixture for two of the mixtures evaluated and using PG 76-22 for the third mixture considered. One may wish to consider lower test temperatures because Lemke and Bahia (2019) reported reducing the test temperature from 60 °C [140 °F] to 52 °C [125.6 °F] when testing PG 58S-28 and PG 58H-28 asphalt because of premature failure. Note 8 includes a suggestion for selecting an alternative test temperature based on the binder if one chooses to do so.

Note 4:The University of Wisconsin at Madison Modified Asphalt Research Center (2017) reported that the City of LA selected 6900 load cycles as the maximum load cycles because “initial observations from tests showed that most samples tested showed their performance well before these values (6900 load cycles and 6.0 mm [0.24 in.]) were attained ... while those that exhibited low rut depth in the field and no moisture susceptibility showed test result curves that behaved as asymptotes to their initial creep slope until the maximum number of cycles (30 000 cycles) of the machine was attained.” 6900 load cycles was used in both the ruggedness and precision work as well. The machine has an allowable range of 300 to 30 000 load cycles.

Note 5:The University of Wisconsin at Madison Modified Asphalt Research Center (2017) reported that the City of LA selected 6.0 mm [0.24 in.] as the maximum rut depth because “initial observations from tests showed that most samples tested showed their performance well before these values (6900 load cycles and 6.0 mm [0.24 in.]) were attained ... while those that exhibited low rut depth in the field and no moisture susceptibility showed test result curves that behaved as asymptotes to their initial creep slope until the maximum number of cycles (30 000 cycles) of the machine was attained.” 6.0 mm [0.24 in.] was used in both the ruggedness and precision work as well.

Note 6:The University of Wisconsin at Madison Modified Asphalt Research Center (2017) reported that the City of LA selected 70 CPM as the loading rate because that is what its RWT was set at by the factory. 70 CPM was used in both the ruggedness and precision work as well. The machine has an allowable range of 60 to 90 CPM.

Note 7:The University of Wisconsin at Madison Modified Asphalt Research Center (2017) reported that the City of LA selected an applied load of 334 N [75 lb] because that is what its RWT was set at by the factory. 334 N [75 lb] was used in both the ruggedness and precision work as well. The machine has an allowable range of 334 to 489 N [75 to 110 lb] in 22-N [5-lb] increments. Applied loads of greater than 334 N [75 lb] are not recommended based on experience.

1.5Criteria for the evaluation and interpretation of test results shall be developed for local conditions and material characteristics. Appendix X1 shows an example of how test results are used and interpreted.

1.6The text of this test method references notes and footnotes which provide explanatory material. These notes and footnotes (excluding those in tables and figures) shall not be considered as requirements of the test method.

1.7Units—The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in nonconformance with the standard.

1.8This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.

1.9This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

ASTM D 6925 : 2023 Standard Test Method for Preparation and Determination of the Relative Density of Asphalt Mix Specimens by Means of the Superpave Gyratory Compactor
ASTM D 6752/D6752M : 2018 Standard Test Method for Bulk Specific Gravity and Density of Compacted Asphalt Mixtures Using Automatic Vacuum Sealing Method
ASTM D 6857/D6857M : 2018 Standard Test Method for Maximum Specific Gravity and Density of Asphalt Mixtures Using Automatic Vacuum Sealing Method
ASTM D 8 : 2022 : REV A Standard Terminology Relating to Materials for Roads and Pavements
ASTM D 1188 : 2007 : R2015 Standard Test Method for Bulk Specific Gravity and Density of Compacted Bituminous Mixtures Using Coated Samples
ASTM D 6027/D6027M : 2024 Standard Practice for Calibration/Verification of Linear Displacement Transducers for Geotechnical Purposes
ASTM D 8 : 2022 Standard Terminology Relating to Materials for Roads and Pavements
ASTM D 2041/D2041M : 2011 Standard Test Method for Theoretical Maximum Specific Gravity and Density of Bituminous Paving Mixtures
ASTM D 6925 : 2015 Standard Test Method for Preparation and Determination of the Relative Density of Asphalt Mix Specimens by Means of the Superpave Gyratory Compactor
ASTM D 6027/D6027M : 2015 Standard Practice for Calibrating Linear Displacement Transducers for Geotechnical Purposes
ASTM D 8 : 2021 Standard Terminology Relating to Materials for Roads and Pavements
ASTM D 3666 : 2016 Standard Specification for Minimum Requirements for Agencies Testing and Inspecting Road and Paving Materials
ASTM E 4 : 2021 Standard Practices for Force Calibration and Verification of Testing Machines
ASTM D 2726/D2726M : 2014 Standard Test Method for Bulk Specific Gravity and Density of Non-Absorptive Compacted Bituminous Mixtures
ASTM D 3666 : 2024 Standard Specification for Minimum Requirements for Agencies Testing and Inspecting Road and Paving Materials
ASTM D 3203/D3203M : 2017 Standard Test Method for Percent Air Voids in Compacted Asphalt Mixtures
ASTM D 6752/D6752M : 2023 Standard Test Method for Bulk Specific Gravity and Density of Compacted Asphalt Mixtures Using Automatic Vacuum Sealing Method
ASTM D 6857/D6857M : 2023 Standard Test Method for Maximum Specific Gravity and Density of Asphalt Mixtures Using Automatic Vacuum Sealing Method
ASTM D 2726/D2726M : 2019 Standard Test Method for Bulk Specific Gravity and Density of Non-Absorptive Compacted Asphalt Mixtures
ASTM E 4 : 2024 Standard Practices for Force Calibration and Verification of Testing Machines

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