Study On Optimum Design And Construction Technique Of ATB-25 Of Chang Ning Expressway

Through research and practice at home and abroad show that in the form of high grade highway pavement structure using dense graded asphalt stabilized macadam base has many advantages,all parts of the our country including Jiangxi Province in recent years,the new highway is also widely used in asphalt stabilized macadam base.Relied on the project of Changning expressway,this paper focused on the systematic research of gradation design and construction technology.The research object is dense graded asphalt stabilized macadam of ATB-25 flexible base.According to the climate and traffic conditions of Jiangxi Provincial,Changning Expressway,and the "Technology Specifications for Asphalt Pavement Construction",this paper employed the aggregate gradation design concept(BaileyBailey,SAC and CAVF)and the volume method idea to form a dense skeleton structure.With the 4.75mm screen as dividing point between the coarse and fine aggregate,the ATB-25 gradation curve is divided into "rough section" and "thin section".According to the relationship between the evaluation index of the skeleton structure and the performance of the hybrid material,the reasonable content of coarse aggregate is obtained.The gradation curve of the "rough section" is recommended by the sequential filling test.Three kinds of models are used to calculate the size of the "thin section" and compare the mixed volume index.The power function model is recommended to calculate the "thin section" gradation curve.At the same time,the author put forward a design method for Asphalt mixture basing on skeleton dense structure.The optimal asphalt content is determined using large Marshall Test method.The N method,I method and Superpave method are used to compare the performance of the road to determine the feasibility of the optimization scheme.According to the climate of Changning expressway,the adaptive standard and method for controlling the raw materials is put forward to monitor quality of the raw materials.Infrared spectrum is used to control the source stability of matrix asphalt.It is confirmed that similar infrared spectrum is obtained in two solvents(chloroform,tetrahydrofuran)during asphalt source stability test.Finally,considering the coarse particle size,slightly faster temperature loss,easy segregation and difficult compaction of the skeleton dense type ATB-25,the non-nuclear density meter(PQI)is used to optimize the spreading and rolling plan for skeleton dense type ATB-25,resulting reduced pavement segregation,controlled compaction,and ensured quality of the overall flexible base.The effectiveness of construction control measures is tested by detecting the ATB-25 of Changning high-speed line.