Standard Test Method for Determination of Cracking Tolerance Index of Asphalt Mixture Using the Indirect Tensile Cracking Test at Intermediate Temperature

Importancia y uso:

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 CT_Index 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 CT_Index 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 CT_Index value, the better the cracking resistance and, consequently, the less the cracking amount in the field. The range for an acceptable CT_Index will vary with mix types and associated specific applications.4 Users can employ the CT_Index 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.

Subcomité:

D04.26

Volúmen:

04.03

Número ICS:

93.080.20 (Road construction materials)

Palabras clave:

asphalt mixture cracking resistance; cracking tolerance index; failure energy; indirect tensile cracking test; work of failure;