Study On Road Performance And Structural Characteristics Of Asphalt Stabilized Macadam With High Modulus

With the steady progress and implementation of the Belt and Road strategy,China is promoting and applying the new technologies in transportation infrastructure construction for the African area.Road traffic facilities in African countries are relatively backward.It is an urgent problem for African highway construction to seek the pavement structure materials and the combination of pavement layers which is suitable for the climate and traffic load conditions in Africa.High modulus asphalt pavement is an effective means to optimize the structure combination of pavement and solve the problem of pavement diseases.The pavement structure with high-modulus asphalt stabilized macadam base(HMAM)is still in the exploration stage.There is also no technical specification for the application of the pavement structure with high modulus asphalt stabilized macadam base that is suitable for the climate conditions and traffic load requirements in Africa.Based on the actual needs of the construction of the external ring road in the Ethiopian capital of Africa,this paper focuses on the study of reasonable gradation composition,material composition design method and construction technology of high modulus asphalt stabilized macadam in order to obtain high modulus asphalt stable macadam with high bearing capacity,long fatigue life and strong deformation resistance,which can be used in the external ring road of Addis.The high modulus agent which is suitable for the pavement structure of Addis external ring road is recommended according to the coMParative analysis of the performance characteristics of the high-modulus asphalt stabilized macadam mixture with different high-modulus agent content.The reasonable gradation composition and range of high-modulus asphalt stabilized macadam HMAM-25 were studied,the method of determining the optimum content of high modulus agent was also studied by grey correlation theory.The basic performance characteristics of the high modulus asphalt stabilized macadam HMAM-25 was evaluated and coMPared by means of lab experiments.The experiment results show that high modulus agent PRM and RA(NZ)can effectively improve the high temperature deformation resistance of asphalt stabilized macadam.The improvement of two types of high modulus agents has effectively improved the dynamic modulus of asphalt stabilized macadam.The water damage resistance,fatigue life and aging resistance of asphalt stabilized macadam were greatly improved too,but the low temperature cracking resistance was weakened.The rational structure combination and mechanical response characteristics of the pavement structure with high modulus asphalt stabilized macadam base used in the external ring road of Addis were studied.The results show that the total thickNess of high-modulus asphalt stabilized macadam base pavement structure can be optimized by 5 % to 10 % based on the Chinese designing specification coMPared to ordinary flexible base pavement structures.The total thickNess of high-modulus asphalt stabilized macadam base pavement structure designed by French specification can be optimized by more than 25 %.The mechanical response analysis of pavement structure with high modulus asphalt stabilized macadam base shows that high modulus asphalt stabilized macadam base and ordinary asphalt stabilized gravel base can effectively reduce the tensile stress of the base bottom and reduce the risk of cracking disease of the pavement under the single axis loading.The high modulus bituminous stabilized macadam base has more advantages on reducing vertical compressive stress,horizontal shear stress,vertical deformation and transverse shear flowing deformation of pavement structure,and improving the crack resistance of pavement base.Under the condition of repeated axial loading,the long-term performance of high modulus asphalt stabilized macadam base pavement is much more superior.Setting up a high modulus asphalt stabilized macadam base for the pavement structure can effectively reduce the horizontal shear stress of the base layer bottom,improve its shear deformation resistance and improve the long-term crack resistance of pavement structures.Through the field construction of asphalt pavement structure with high modulus asphalt stabilized macadam base used in the external ring road of Addis,the construction technologies and quality control measures of high modulus asphalt stable macadam were studied.Some relevant observation elements were laid on the pavement structure of the testing road in order to check the applying effect of high modulus asphalt stabilized macadam HMAM-25 used in the asphalt pavement structure for the external ring road of Addis.The observation results of field testing road show that high modulus asphalt stabilized macadam base can effectively prevent cracking disease of pavement structure although the base bottom is in a tensile strain state.The research on the flexible pavement structure with high modulus asphalt stabilized macadam base is of great significance to enrich the asphalt pavement structure and improve the pavement construction technology.