Abstract
AC (asphalt concrete)-13, as the main material used in pavement construction, has been applied widely in seasonal frozen areas. In order to understand the fracture mechanism in the freeze-thaw (F-T) damage process, the mesoscale structure of AC-13 is obtained by computed tomography (CT). The fractal dimension of cracks is used as a damage evaluation index. Most previous studies have only focused on the fractal dimensions of whole cracks, while ignoring the fractal tectonic process and the self-similarity degree of a single fracture. Therefore, in this study, the intrinsic mechanism of fractures and damage were investigated. In addition, the critical crack stress and fracture toughness models of a single fracture in a freeze-thaw damage process are established for AC-13. The results indicate that in terms of the critical crack stress and fracture toughness, with the increase of F-T times, there is an obvious decreasing trend. The fracture model can effectively describe the fracture toughness calculated by ABAQUS in the process of freeze-thaw cycles.
Highlights
Asphalt concrete is the most common pavement construction material for each level of roads; it is characterized by the advantages of energy savings, emissions reductions and superior skid resistance [1,2]
17, the elastic modulus deteriorates with increasing the freeze-thaw cycles, and decreases rapidly in theininitial freeze-thaw cycles. This is due to the micro cracks in asphalt concrete caused by freeze-thaw caused by freeze-thaw cycle damage, which leads to a considerable decline in overall integrity rapidly in the initial freeze-thaw cycles.This
The calculated data is in good agreement with the measured data, indicating that the fracture toughness calculation model, considering the fractal characteristics proposed in this study, is reasonable
Summary
Asphalt concrete is the most common pavement construction material for each level of roads; it is characterized by the advantages of energy savings, emissions reductions and superior skid resistance [1,2]. In seasonal frozen areas, thermal cracking caused by the contraction and expansion of asphalt under freeze-thaw cycles causes major pavement damage, and could cause many disasters, such as pavement cracking and mud boiling [5,6,7]. These phenomena shorten the service life of asphalt concrete. Omranian et al compared the maximum stresses at failure, fracture toughness, and fracture energy by a semicircular asphalt concrete bending test; the velocity of fracture initiation, velocity of crack growth, and fragility index were proposed to better understand the fracture behavior of asphalt mixtures with respect to the mixtures’ crack resistance and its propagation [23]. The models of critical crack stress and fracture toughness for a single fracture based on fractal characteristics will be established to better understand the intrinsic mechanisms of fractures and damage in the process of freeze-thaw cycles
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