Experimental Study And Evaluation Of Adhesion Capacity Of Asphalt And Aggregates Based On AFM Testing Technology

The adhesion performance between asphalt and aggregate directly affects the road performance of asphalt mixture,and the impact on water stability is more important.At present,tests for evaluating adhesion include boiling method,pull-off test,photoelectric colorimetry,surface energy theory,etc.,but the evaluation of adhesiveness is still in macroscopic and empirical evaluation.As AFM in the microscopic scale,the advantages of surface morphology and mechanics of materials can be applied in the field of roads.In this paper,AFM test parameters and traditional evaluation methods are comprehensively analyzed in order to provide a more reliable method for microscopic evaluation of adhesive performance and later impact on the asphalt mixture's road performance.According to the standard test methods and test precautions,the selected materials were subjected to conventional boiling test,pull-off test,and contact angle test,and the asphalt-aggregate adhesion properties were evaluated initially.The test results showed that The conclusion was consistent when evaluating the adhesion between aggregates.Secondly,compared the AFM test program,determine the test parameters,optimize the preparation method of asphalt,according to the principle.of not destroying the molecular structure of asphalt and the effect of aging degree,compare the different methods,and propose the best preparation method.The micro-texture observation of the asphalt surface was performed by the AFM tapping mode,and the change rule of the morphology and micro-morphology parameters of the asphalt at different periods was analyzed,and the change of the micro-morphology of the asphalt was analyzed based on the change of the components during the aging of the asphalt.The reason was that the adhesion between the asphalt surface and the probe was obtained using the AFM contact mode.Based on the JKR(S)calculation model,the surface energy of the asphalt at different times was obtained,and the asphalt surface energy was compared with the contact angle.The results showed that the The AFM obtained a good correlation between the surface energy of the asphalt and the contact angle test method to obtain the surface energy.Finally,based on the Young's method,the adhesion energy between the two materials can be obtained by the surface energy of the two materials,and the correlation analysis is performed according to the boiling method and the pull-out test results.The results show that the adhesiveness evaluation is based on AFM testing technology.It has a good relationship with the traditional evaluation methods,and comprehensively analyzes the relationship between the microscopic structure of asphalt and macroscopic adhesion,and analyzes the reasons for the change of adhesion from the microscopic scale,and provides a more in-depth study of the macroscopic and microscopic dimensions of the mixture for the later period.There is a possibility between material changes.