Abstract
Low-temperature cracking is a major form of distress that can compromise the structural integrity of asphalt pavements located in cold regions. A review of an Acoustic Emission (AE)-based approach is presented that is capable of assessing the low-temperature cracking performance of asphalt binders and asphalt pavement materials through determining their embrittlement temperatures. A review of the background and fundamental aspects of the AE-based approach with a brief overview of its application to estimate low-temperature performance of unaged, short-term, and long-term aged binders, as well as asphalt materials, is presented. The application of asphalt pavements containing recycled asphalt pavement (RAP) and recycled asphalt shingles (RAS) materials to thermal cracking assessment is also presented and discussed. Using the Felicity effect, the approach is capable of evaluating the self-healing characteristics of asphalt pavements and the effect of cooling cycles upon their fracture behavior. Using an iterative AE source location technique, the approach is also used to evaluate the efficiency of rejuvenators, which can restore aged asphalt pavements to their original crack-resistant state. Results indicate that AE allows for relatively rapid and inexpensive characterization of pavement materials and can be used towards enhancing pavement sustainability and resiliency to thermal loading.
Highlights
The majority of the roads in United States are surfaced with asphalt material, indicating the importance of this material in U.S transportation infrastructure
These spiral cracks are a result of the three-dimensional state-of-stress field that develops in each block by the constraints imposed by the granite block
In addition to observing that the spiral pattern represents the crack trajectory with maximum energy release, it was observed that the Acoustic Emission (AE) obtained embrittlement temperatures and fracture energy are related to the spiral crack tightness parameter [38]
Summary
The majority of the roads in United States are surfaced with asphalt material, indicating the importance of this material in U.S transportation infrastructure. Li et al [24,25,26,27,28] used AE techniques to characterize fracture in semi-circular bend asphalt specimens at low temperatures (−20 ◦ C) They concluded that large amounts of accumulated AE events occur at 70% of material strength, that the maximum intensity of AE peaks correlates with the development of macro-cracks, and that the location of AE events suggests that a several centimeter-sized process zone forms before the peak load. Bouldin et al [13] presented methods for predicting cracking temperatures using both the BBR and the DTT test data in the so-called dual instrument method (DIM) These methods involve the use of sophisticated computer software for computing thermal stress in asphalt binders using the bending beam rheometer (BBR) data and estimating binder strength using the direct tension test (DTT). For more details regarding experimental setups, etc., the readers are encouraged to refer to the appropriate citations
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