Assessing Crack Susceptibility of Asphalt Concrete Mixtures with Overlay Tester

2018 ◽  
Vol 46 (3) ◽  
pp. 20170006 ◽  
Author(s):  
Victor M. Garcia ◽  
Alejandro Miramontes ◽  
Jose Garibay ◽  
Imad Abdallah ◽  
Soheil Nazarian
Author(s):  
Victor M. Garcia ◽  
Jose Garibay ◽  
Imad Abdallah ◽  
Soheil Nazarian

Several highway agencies have either implemented or considered implementing laboratory performance tests to estimate the cracking potential of asphalt concrete (AC) mixes during the mix design process. One such popular test, the overlay tester (OT), measures the number of cycles to failure of specimens that are caused by the repeated application of deformation. The major concern about using this test as a reliable characterization of the cracking susceptibility of AC mixes, especially for dense-graded mixtures, is the variability in the specified number of cycles to failure in the performance index. The main objective of this paper is to report a means for improving the consistency of the OT test results on dense-graded AC mixes. An assessment of a specimen preparation process that can yield more consistent results was conducted. The consistency of the traditional number of cycles to failure as well as of the load–displacement response and load reduction curves was investigated by using a modified specimen preparation process. The repeatability of alternative performance indexes, such as the critical fracture energy and crack progression rate, that can be measured from the OT test was also investigated and compared with that of the index for the number of cycles to failure. This study indicated that the raw data from the OT test seemed to be repeatable if the proposed specimen preparation process was consistently followed. Alternative performance indexes that yielded an acceptable degree of repeatability may be readily implemented in the OT test to assess the cracking characteristics of AC mixes.


Vestnik MGSU ◽  
2015 ◽  
pp. 110-119 ◽  
Author(s):  
Svetlana Yur’evna Shekhovtsova ◽  
Marina Alekseevna Vysotskaya

In the modern world nanotechnologies are an integral part of successful and progressive development of all the areas of activity. Materials science is not an exception. The authors studied the method of nanomodification and its influence on the performance properties of polymer-modified binder (PMB) and asphalt concrete, produced on their basis. It is established that nanomodified PMB are less susceptible to aging, which is a consequence of the processes of peptization of asphalt-resin complexes (ARC) in the structure of the modified binder and the crosslinking with the polymer matrix. It is revealed that nanotubes (SWCN or MWCN) used as a modifier, act as crosslinking agent and the inhibitor of the aging process in a PMB. The influence of nanomodified PMB on strength and deformation properties of asphalt concrete is investigated. It was found out that the use of modified binder in the asphalt concrete mixtures enhances the water resistance of asphalt concrete, heat resistance and shear-resistance.


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