Study On Fatigue Characteristics And Decay Prediction Of In-place Hot Recycled Asphalt Pavement In Hot And Humid Areas

The maintenance demand of asphalt pavement in highway network is increasing,which also indicates that China's highway industry has entered an era of both construction and maintenance.As a common preventive maintenance method in China,in-situ thermal regeneration technology has paved a large number of physical projects,especially in Jiangxi Province.Jiangxi Province is a typical hot and humid area with special climatic conditions.Moreover,in-situ thermal regeneration technology of asphalt pavement is less widely used in domestic high-grade highways in hot and humid areas,and its research results are relatively insufficient.The existing research mainly focuses on the design of asphalt mixture,recycling agent and construction control of in-situ thermal recycling.For in-situ thermal recycling,the service life of recycled asphalt pavement is an important factor affecting the decision-making of in-situ thermal recycling pavement maintenance and treatment.Based on a thorough understanding of the general situation of the Chang-Jiu Expressway and Jiu-Jing Expressway,this paper analyses the traffic condition of the insitu thermal regeneration section,and through the investigation of the diseases of the insitu thermal regeneration section of Chang-Jiu Expressway and Jiu-Jing Expressway,comparing the proportion of the accumulated area of the pavement diseases before and after in-situ thermal regeneration maintenance,it can be concluded that the causes of pavement diseases before and after in-situ thermal regener this is the same.Through literature research and practical engineering research,the long-term performance index of in-situ thermal regeneration in hot and humid areas is discussed in depth.The sensitivity of fatigue performance of in-situ thermal recycled pavement is analyzed and compared with the change of modulus and thickness of each structural layer,asphalt saturation and vehicle load,and the influence of void ratio of in-situ thermal recycled pavement and bond strength of each structural layer on the fatigue performance of in-situ thermal recycled pavement is compared and analyzed.The fatigue observation index can be divided into important index and secondary index,specifically referring to in-situ thermal recycled pavement.Tables 3-28;Rutting depth index should be taken as the main index to evaluate the rutting diseases of in-situ thermal recycling,RAP mixing rate and temperature as the secondary index during in-situ thermal recycling construction;water damage related observation index in long-term performance research of in-situ thermal recycling asphalt pavement should be drawn up,which is loose,pit,asphalt pavement porosity,total rainfall in rainy season;and in-situ thermal recycling asphalt pavement should be determined.The functional indexes of pavement surface are determined as structural depth,lateral force coefficient and smoothness.Field calibration of in-situ thermal recycling asphalt pavement fatigue prediction model in hot and humid areas is mainly based on the long-term observation data of insitu thermal recycling section of Chang-Jiu Expressway.The AI MS-1 model,the improved AI MS-1 model,the constant stress and constant strain comprehensive model,and the field verification and coefficient correction based on the model coefficient MF model are carried out respectively.In order to adjust the parameters of each model and evaluate the advantages and disadvantages of each model,a fatigue prediction model for in-situ hot recycled asphalt pavement in hot and humid areas is proposed.Considering that the performance decay law of in-situ thermal recycled pavement is basically the same as that of ordinary asphalt pavement,on the basis of referring to the performance decay model of common pavement in foreign countries,the research data of Changjiu Expressway,Fuyin Expressway,Wensha Section,Wuji Expressway,Taijing Expressway and Jiujing Expressway in Jiangxi Province are brought into the model,and the parameters of the model are re-weighted by the method of binary linear regression.With the new calibration,the performance degradation model of in-situ thermal recycled pavement suitable for hot and humid areas is obtained.