Temperature dependency analysis of the fracture characteristics of semi-flexible pavement (SFP) mixtures using acoustic emission technique

ABSTRACTABSTRACTThe poor cracking resistance of Semi-Flexible Pavement (SFP) mixture has limited its wider application. Particularly, the dual skeletal interlocking structure makes its damage process complicated. Its fracture process is expected to change with aggregate gradation and temperature, but the relevant knowledge is very limited. Thus, this study aims to investigate the effects of the two factors on the fracture characteristics of SFP using the acoustic emission (AE) technique and X-ray computed tomography (CT) approach. SFP specimens with three gradations (the target cement grout volume is 22%, 25% and 30%, respectively) were fabricated and subjected to the split tensile tests at three different temperatures (−10°C, 10°C and 25°C). Machine learning-based techniques were applied to analyze the AE signals to improve the understanding of the mesoscale damage process. Although the analysis of macro mechanical parameters showed the diminishing effect of temperature dependency on the fracture process with an increase in cement grout volume, the effect was found to be still significant based on the mesoscale analysis. Besides, it was found that the damage process transferred from the main crack going through cement to distributed meso-cracks in asphalt and cement with the temperature increase.KEYWORDS: Semi-flexible pavement materialsplitting processfracture characteristicdamage modeacoustic emissionpattern recognition Disclosure statementNo potential conflict of interest was reported by the author(s).Additional informationFundingThe work described in this paper was partially supported by a grant from the National Key R&D Program of China (No.: 2021YFB2601000), Research Grants Council of the Hong Kong Special Administrative Region, China (PolyU 15204022 for GRF project funded in 2022/23 Exercise) and the National Natural Science Foundation of China (No. 52208283).