Modelling the flushing mechanism of thin flexible surface pavements

The research presented in this thesis investigated the occurrence of flushing of chip seal pavements. The research aimed to determine the effects of volumetric properties of chip seal surfaces on flushing, focusing on the relationship between air voids and flushing initiation. Additionally, the research aimed to develop a pavement deterioration model to predict the initiation and progression of flushing on chip seal pavements. Mechanical testing was conducted on cores obtained from in-service, flushed chip seal pavements from Auckland, Waikato, Christchurch and Dunedin regions of New Zealand. The tests that were performed on the cores included wheel tracking, air voids measurement, bitumen extractions and sieve analyses to determine aggregate grading profiles. Measurements were made of the depth and pattern of deformation that had developed on the cores during wheel tracking. Samples extracted from tested cores were scanned using a computed tomography scanner and the scan images were analysed using image analysis techniques to calculate the volume of air voids within the samples. The reduction in air void volume during wheel tracking was compared to the flushing that had occurred on the samples to establish the relationship between flushing and air voids. Furthermore, data analysis was performed on pavement condition data gathered from New Zealand’s long-term pavement performance database to identify the combination of factors that provided the best prediction of flushing, and regression analysis was performed to develop a model to predict the initiation and progression of flushing. Using these research outcomes, a pavement condition assessment guideline was developed to aid with managing flushed pavements. Overall, this research has significantly increased the understanding of the mechanisms that lead to flushing and established ways to better identify and manage flushing.


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Filing Info

  • Accession Number: 01534328
  • Record Type: Publication
  • Source Agency: ARRB
  • Files: ITRD, ATRI
  • Created Date: Aug 11 2014 2:46PM