Research On Low Tempereture Cracking Evaluation And Control Index Of Asphalt Pavement Based On LTPP

Low temperature cracking of asphalt pavement in frozen zone is the mostpopular and noteworthy pavement damage form, and the research on it is favored bymore and more scholars at home and abroad. LTPP database has much resource, sothe research bases on LTPP database at a different way. Using statistical knowledgeand analysing data from LTPP database to evaluate low temperature cracking ofasphalt pavement and to study its control index in North America region, this thesisestablished the model of low temperature cracking and ride comfort of asphaltpavement.Firstly, this thesis mines and analyses the LTPP database. Using MAPGIS todevide the freezing areas in North America region based on the maximum value offreezing index monitored for many years, it was devided heavy freezing area,middle freezing area, light freezing area and non-freezing area according to the800,2000℃boundary value of freezing index. And the states or provinces of differentareas to study were found out on the basis of the integrity of LTPP data, then the testsections to study were categorized according to defferent road levels. In addition,Minnesota was identified as the typical research object according to the asphalt PGdistribution and the latitude contrast to Harbin city in China.Secondly, in order to research on control index of low temperature cracking ofasphalt pavement, it is necessary to grasp the evolution of low temperature crackingand its effects on other performance. Through the statistics and classification ofLTPP survey data on asphalt pavement, low temperature cracking at heavy freezingarea and middle freezing area were evaluated respectively, which included theevolution analysis of low temperature cracking, the impacts on maintenance andreconstruction of low temperature cracking and the evaluation on the present overallsituation of low temperature cracking.In addition, through the statistics and studying of LTPP pavement structureperformance, the evolution modle of ride comfort and service life was established,and then the relationship between low temperature cracking and ride comfort wasstudied. The IRI(international roughness index) and L(the cumulative length of lowtemperature cracking) were main indicators. Through the typical analysis ofMinnesota, the two modles of IRI with N(service life) and IRI with L wereestablished. Considering the acceptable degree on low temperature cracking ofasphalt pavement from the users’ perspective of ride comfort, the degree on lowtemperature cracking was evaluated and controled through the acceptability andspecification requirements of IRI. Finally, the models and standards coming from LTPP database were comparedand validated for the application in China based on the Delphi method. Thequestionnaires were sent to the experts in the field of construction, supervision,investigation, design, management and scientific research from13provinces(municipalities and autonomous regions), and the range of control index and theallowing degree of low temperature cracking in the north of China were confirmedat the macro and experience angle. The aforementioned allowing degree andstandards of low temperature cracking based on LTPP were analysed for thedifferences and applicability in China by the comparison of the Delphi method.