Abstract
The thermodynamic behavior of asphalt mixtures is critical to the engineers since it directly relates to the damage in asphalt mixtures. However, most of the current research of the freeze-thaw damage of asphalt mixtures is focused on the bulk body from the macroscale and lacks a fundamental understanding of the thermodynamic behaviors of asphalt mixtures from the microscale perspective. In this paper, to identify the important thermodynamic behaviors of asphalt mixtures under freeze-thaw loading cycle, the information entropy theory, an X-ray computerized tomography (CT) scanner and digital image processing technology are employed. The voids, the average size of the voids, the connected porosity, and the void number are extracted according to the scanned images. Based on the experiments and the CT scanned images, the information entropy evolution of the asphalt mixtures under different freeze-thaw cycles is calculated and the relationship between the change of information entropy and the pore structure characteristics is established. Then, the influences of different freezing and thawing conditions on the thermodynamic behaviors of asphalt mixtures are compared. The combination of information entropy theory and CT scanning technique proposed in this paper provides an innovative approach to investigate the thermodynamics behaviors of asphalt mixtures and a new way to analyze the freeze-thaw damage in asphalt mixtures.
Highlights
Asphalt mixture, which is one of the most widely used pavement materials, is a viscoelastic material that is very sensitive to the external environmental conditions [1,2]
The variation of pore structure characteristics for AC and open-graded friction course (OGFC) mixtures with various F-T cycles in T-1 test procedure were analyzed by utilizing X-ray computerized tomography (CT) images, as demonstrated in Figures 2 and 3
A parabola going downward existed in the curve of the samples treated by. This phenomenon indicated the differences of failure mechanism of asphalt mixtures between the two experimental conditions
Summary
Asphalt mixture, which is one of the most widely used pavement materials, is a viscoelastic material that is very sensitive to the external environmental conditions [1,2]. Changes in the weather conditions, such as the alternation of freezing and thawing cycles may alter the internal structure and may result in the initial damage of asphalt pavement [3,4]. To study the distress initiation and development in asphalt pavement with freeze-thaw (F-T) actions, the determination of initiation and development of damage inside asphalt mixture needs to be firstly explored. The difficulty associated with the identification of F-T damage in asphalt mixtures at different scales has significantly hindered the analysis on the comparison of macro-scale properties (such as strength, modulus, and macro-scale air voids content) before and after F-T cycles in asphalt pavement design. Consider the importance of this kind of distress, the influence of F-T action on the degradation of asphalt pavements has been analyzed
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