Study On Nanostructure And Adhesion Of Asphalt Surface In Normal Temperature Range

The early damage of asphalt concrete pavement,such as loose and falling grain,is closely related to the adhesion property of asphalt aggregate.In the service period of asphalt pavement,the change of temperature has an influence on the adhesio n between the asphalt and aggregate.However,most scholars at home and abroad just studied the influence from a macro perspective because of the previous limitations of science and technology.Nowadays,it is possible for us to study the effects of temperature on the asphalt nanostructure and mechanical properties with the development of atomic force microscope(AFM)and the popularity of multiscale study in asphalt.Therefore,we have studied four kinds of asphalt which came from two types of oil source using the AFM technology,and explored the mechanism of asphalt adhesion along with the nano-scale research of four asphalt components.We have selected four kinds of asphalt including Anda 50#,90#,SK70# and SK-SBS.And then,we made the asphalt samples and the four components samples using hot casting method and dissolved method respectively.The samples were then tested in different temperatures by the technology of AFM.And the results showed that the maximum temperature of the seleted asphalt can be 65? while the components' were different.When tested in higher temperature,the morphology and the force curves are meaningless since the frequent jumps of the tip and the dislocation of the Trace and the Retrace lines.In addition,it was found that Anda asphalt contains bee structures while the SK asphalt did not.But the SK asphalt also contained special structures distributed evenly.Besides,bee structures were found in the aromatic fraction of the four components after heated for once.The QNM model was perfomed to scan the morphology and force curves of the samples in different temperatures.And then the Nano Scope Analysis software was used to analysis the roughness parameters in the nano morphology and the adhesion in the adhesion force distribution maps.It was found that there was a good correspondence between the nano morphology and the adhesion force distribution maps in the asphalt while wasn't in the components.The Oliver-Pharr model was applied to analysis the nano hardness of the asphalt and its components at different temperatures.And the results showed big difference among the different asphalt or components.Finally,macro peeling tests were carried out on the asphalt under normal temperature.The results showed that the peeling force of the asphalt decreased rapidly with the increase of temperature.Besides,the cohesive failure became the major failure mode of the peel samples.Comparing the nano adhesion and surface roughness with the corresponding asphalt macro peeling force,it was found that the trends varies from the macroscopic test results because of the different failure modes.