ASTM D8225-19
(Test Method)Standard Test Method for Determination of Cracking Tolerance Index of Asphalt Mixture Using the Indirect Tensile Cracking Test at Intermediate Temperature
Standard Test Method for Determination of Cracking Tolerance Index of Asphalt Mixture Using the Indirect Tensile Cracking Test at Intermediate Temperature
SIGNIFICANCE AND USE
5.1 The indirect tensile cracking test is used to determine asphalt mixture cracking resistance at an intermediate temperature which could range from 5 °C to 35 °C, depending on local climate. The specimens are readily obtained from Superpave gyratory compactor compacted cylinders with a diameter of 150 ± 2 mm, with no cutting, gluing, notching, drilling, or instrumentation required. Similarly, field cores can be tested to measure remaining cracking resistance of in-place asphalt mixtures.
5.2 The CTIndex of an asphalt mixture is calculated from the failure energy, the post-peak slope of the load-displacement curve, and deformation tolerance at 75 % of the peak load. The CTIndex is a performance indicator of the cracking resistance of asphalt mixtures containing various asphalt binders, asphalt binder modifiers, aggregate blends, fibers, and recycled materials. Generally, the higher the CTIndex value, the better the cracking resistance and, consequently, the less the cracking amount in the field. The range for an acceptable CTIndex will vary with mix types and associated specific applications.4 Users can employ the CTIndex and associated criteria to identify crack-prone mixtures during mix design and production quality control/assurance.
Note 1: The quality of the results produced by this standard are dependent on the competence of the personnel performing the procedure and the capability, calibration, and maintenance of the equipment used. Agencies that meet the criteria of Specification D3666 are generally considered capable of competent and objective testing, sampling, inspection, etc. Users of this standard are cautioned that compliance with Specification D3666 alone does not completely ensure reliable results. Reliable results depend on many factors; following the suggestions of Specification D3666 or some similar acceptable guideline provides a means of evaluating and controlling some of those factors.
SCOPE
1.1 This test method covers the procedures for preparing, testing, and measuring asphalt mixture cracking resistance using cylindrical laboratory-prepared asphalt mix samples or pavement cores. Testing temperatures are selected from the long-term pavement performance (LTPP) database intermediate temperatures. The test method describes the determination of the cracking tolerance index, CTIndex, and other parameters determined from the load-displacement curve. These parameters can be used to evaluate the resistance of asphalt mixtures to cracking.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 The text of this standard 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 standard.
1.4 This 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.
1.5 This 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.
General Information
Relations
Standards Content (Sample)
This 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.
Designation: D8225 − 19
Standard Test Method for
Determination of Cracking Tolerance Index of Asphalt
Mixture Using the Indirect Tensile Cracking Test at
1
Intermediate Temperature
This standard is issued under the fixed designation D8225; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
2
2.1 ASTM Standards:
1.1 This test method covers the procedures for preparing,
D8 Terminology Relating to Materials for Roads and Pave-
testing, and measuring asphalt mixture cracking resistance
ments
using cylindrical laboratory-prepared asphalt mix samples or
D3203/D3203M Test Method for PercentAir Voids in Com-
pavement cores. Testing temperatures are selected from the
pacted Asphalt Mixtures
long-term pavement performance (LTPP) database intermedi-
D3666 Specification for Minimum Requirements for Agen-
ate temperatures. The test method describes the determination
cies Testing and Inspecting Road and Paving Materials
of the cracking tolerance index, CT , and other parameters
Index
D6373 Specification for Performance Graded Asphalt
determined from the load-displacement curve. These param-
Binder
eters can be used to evaluate the resistance of asphalt mixtures
D6925 Test Method for Preparation and Determination of
to cracking.
the Relative Density ofAsphalt Mix Specimens by Means
1.2 The values stated in SI units are to be regarded as
of the Superpave Gyratory Compactor
3
standard. No other units of measurement are included in this 2.2 AASHTO Standards:
standard.
R30 Practice for Mixture Conditioning of Hot Mix Asphalt
(HMA)
1.3 The text of this standard references notes and footnotes
M 320 Specification for Performance-Graded Asphalt
which provide explanatory material. These notes and footnotes
Binder
(excluding those in tables and figures) shall not be considered
M 332 Specification for Performance-Graded Asphalt
as requirements of the standard.
Binder Using Multiple Stress Creep Recovery (MSCR)
Test
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3. Terminology
responsibility of the user of this standard to establish appro-
3.1 Definitions:
priate safety, health, and environmental practices and deter-
3.1.1 For definitions of terms used in this standard, refer to
mine the applicability of regulatory limitations prior to use.
Terminology D8.
1.5 This international standard was developed in accor-
3.2 Definitions of Terms Specific to This Standard:
dance with internationally recognized principles on standard-
3.2.1 CT ,n—cracking tolerance index, value used to
Index
ization established in the Decision on Principles for the
evaluate mixture resistance to cracking.
Development of International Standards, Guides and Recom-
2
3.2.2 G,n—failure energy (Joules/m ) required to induce a
mendations issued by the World Trade Organization Technical f
unit surface area of a crack and calculated as the work of
Barriers to Trade (TBT) Committee.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
1
This test method is under the jurisdiction of ASTM Committee D04 on Road Standards volume information, refer to the standard’s Document Summary page on
and Paving Materials and is the direct responsibility of Subcommittee D04.26 on the ASTM website.
3
Fundamental/Mechanistic Tests. Available from American Association of State Highway and Transportation
Current edition approved April 1, 2019. Published April 2019. Originally Officials (AASHTO), 444 N. Capitol St., NW, Suite 249, Washington, DC 20001,
approved in 2019. DOI: 10.1520/D8225-19. http://www.transportation.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D8225 − 19
failure divided by specimen diameter (150 6 2 mm) and 4.2 This test procedure considers both crack initiation and
normalized thickness of 62 mm. propagation in asphalt mixtures, and is developed based on
4
fracture mechanics.
3.2.3 l ,n—displacement (mm) corresponding to 65 % of
65
the peak load at the post-peak stage. See Fig. 1.
5. Significance and Use
3.2.4 l ,n—displacement (mm) corresponding to 75 % of
75 5.1 The indirect tensile cracking test is used to determine
the peak load at the post-peak stage. See Fig. 1.
asphaltmixturecrackingresi
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