This paper investigated the use of AE in characterizing the fracture behavior of asphalt mixtures and presented the details of a method using the AE location technique to identify the crack path in asphalt mixtures at low temperatures. An example of the application of the method to fracture tests performed using the semi circular bend (SCB) test on 58-34 mixtures at -20 deg C was presented. Loose asphalt mix used in the construction of cell 33 at the MnRoad facility was used to prepare SCB specimens that were tested with a closed-loop servo hydraulic test frame under the crack mouth opening displacement control. An automatic data acquisition system was used to record the AE events with a network of seven piezoelectric sensors. An algorithm was developed to automatically detect the relative arrival time of elastic waves recorded at each sensor and to locate AE events. The locations of AE events clearly indicated the localization of the deformation under external loading. Furthermore, the use of a collapsing algorithm to relocate the recorded AE events resulted in a good prediction of the crack path. The analysis of the accumulated AE events showed that large amounts of AE events start to occur only when the stress reaches a certain level (70 % in this study) of the strength. The intensity of the AE activity peaks around the load when a macrocrack develops. The locations of AE events indicates that a process zone forms before the peak load, which eventually becomes the failure plane, and the movement of this process zone identifies propagation in the macroscale. This makes the location of AE events a promising tool for the observation of crack initiation and propagation in asphalt mixtures. By combining this AE technique with the SCB test, the mechanism of the low temperature cracking can be studied at both the microscopic and macroscopic level. The authors have applied the AE technique to observe the development of micro damage at different low temperatures in the SCB test and the Superpave IDT test and the data will be published in other places. This will result in a better understanding of the fracture mechanism in asphalt materials and in the identification of the main factors responsible for improved fracture resistance of asphalt materials.


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    Title :

    Observation of crack propagation in asphalt mixtures using acoustic emission


    Additional title:

    Beobachtung des Risswachstums in Asphaltmischungen mittels Schallemission


    Contributors:
    Li, X. (author) / Marasteanu, M.O. (author) / Iverson, N. (author) / Labuz, J.F. (author)


    Publication date :

    2006


    Size :

    21 Seiten, 9 Bilder, 22 Quellen


    Type of media :

    Conference paper


    Type of material :

    Storage medium


    Language :

    English




    Observation of Crack Propagation in Asphalt Mixtures with Acoustic Emission

    Li, Xue / Marasteanu, Mihai / Iverson, Nathan et al. | Transportation Research Record | 2006


    Observation of Crack Propagation in Asphalt Mixtures with Acoustic Emission

    Li, Xue / Marasteanu, Mihai O. / Iverson, Nathan et al. | Transportation Research Record | 2006



    Evaluation of Crack Propagation Properties of Asphalt Mixtures

    Mobasher, B. / Mamlouk, M. S. / Lin, H.-M. | British Library Online Contents | 1997