科研之友
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摘要
"Fatigue cracking" is defined as the accumulation of reflective cracking on hot-mix asphalt (HMA) layers under the repeated application of vehicular loads combined with climatic effects. Several highway agencies have either implemented or considered implementing the overlay tester (OT) to evaluate the fatigue cracking resistance of HMA specimens as a function of the number of cycles that the specimen may resist during the test until a reflective crack appears and propagates. The repeatability of the number of cycles to failure measured with the OT is considered as one of the main challenges in reliably evaluating the fatigue cracking resistance of asphalt mixtures. The objective of this paper is to discuss some of the sources and causes of variability of the parameters measured with the OT. Some of the possible causes of inconsistency in the results include the amount of torque applied to attach OT specimens, the amount of glue required for each OT specimen, the curing time of the glue, and the elapsed time between preparation and testing. For a better delineation of the uncertainties associated with the preparation process of HMA specimens and the mechanism of the OT equipment, a thorough study and practical laboratory evaluation of key steps involved in the overlay test protocol were performed on several synthetic and HMA specimens. Through the investigation of the important inconsistencies in the future guidelines, the variability and repeatability of the results from the OT on the number of cycles to failure may be improved.
- 出版日期2015
