Study On Adhesion Characteristics Of Asphalt And Aggregate In High And Cold Areas Of Northeastern Inner Mongolia

Asphalt pavement in the high and cold areas of Northeastern Inner Mongolia is prone to cracks due to low temperature and large temperature difference.The adhesion characteristics of asphalt and aggregate will seriously affect the crack resistance and service life of asphalt pavement.Therefore,it is urgent to conduct deeply research on the adhesion characteristics of asphalt and aggregate of this area.The main work and achievements of this paper are as follows:(1)According to the project,90# matrix asphalt,rubber asphalt,extremely cold asphalt,SBS modified asphalt,SBR modified asphalt and andesite,basalt and limestone are selected as test raw materials.The basic properties of the five kinds of asphalt were tested and the main compound composition of the three aggregates was tested by X-ray fluorescence spectroscopy(XRF),and the adhesion mechanism was analyzed.The results show that andesite is a neutral aggregate,and the high-valent cation content of andesite is low.The adsorption layer formed by chemical adsorption with asphalt is unstable and has poor adhesion to asphalt.(2)Five kinds of asphalt were scanned by atomic force microscopy(AFM)to analyze the effect of adhesion of asphalt to aggregate.The results show that there is a “bee-structure” in the matrix asphalt,and there is no “bee-structure” in the four modified asphalts,and the surface microscopic morphology is frosted/burr-like;The surface roughness of 90# matrix asphalt is about 10 times that of modified as phalt,indicating that the “bee-structure” greatly affects the surface roughness of asphalt.(3)Three aggregates were scanned by atomic force microscopy(AFM)to analyze the effect of adhesion between asphalt and aggregate.The results show that the microstructures of the three aggregates are obviously different.The limestone and basalt have oblique texture.The surface texture of limestone is relatively regular,but the basalt has no obvious law.Andesite has obvious "bright spots" with large surface undulations,and the surface roughness of the three aggregates is consistent with the undulation of the aggregate surface observed on the AFM three-dimensional topographic map of the aggregate.(4)The contact angle test of five asphalts and three aggregates was carried out by the lying drop method.The surface free energy and its components of asphalt and aggregate were calculated based on the surface free energy theory,and the adhesion work of asphalt and aggregate under water and anhydrous conditions was calculated.The results show that the surface energy of the aggregate is greater than the asphalt;and the rubber asphalt and limestone have larger surface energy and higher adhesion work,indicating that the rubber asphalt and limestone have better adhesion;and the adhesion work between asphalt and aggregate under water conditions is less than that under anhydrous conditions.(5)The macroscopic adhesion test was carried out on five asphalts and three aggregates by the pull-off test,and the adhesion between the asphalt and the aggregate was used as an evaluation index of adhesion.The results show that the adhesion between rubber asphalt and three aggregates is significantly greater than that of other asphalts,and the adhesion between rubber asphalt and limestone is the largest,and the macroscopic adhesion between rubber asphalt and limestone is the best.(6)Based on the grey correlation theory,the correlation between asphalt surface energy,aggregate surface energy,asphalt roughness and aggregate roughness and macroscopic adhesion was analyzed.The results show that the degree of influence of various factors on adhesion is: asphalt surface energy > aggregate surface energy > aggregate roughness > asphalt roughness.