Research On Adhesion Between Aggregate And Asphalt Based On Mineralogical Theory

The moisture damage of asphalt mixture is one of the most common defects of the asphalt pavement.The adhesion between aggregate and asphalt has a direct impact on the resistance of moisture damage as well as the strength of asphalt mixtures.Therefore,the adhesion can be an effective way to judge the moisture damage of asphalt mixture.When choosing the aggregate in a real project,the acidity and the adhesion level of aggregate should be considered.However,the current standard adopts the boiling method to evaluate the adhesion level,which has several shrotcomings,for example,the result has a subjective influence,has a low distinction and cannot be evaluated quantitively.Also,the essential mineralogical property of aggregate is deeply connected to the adhesion with asphalt.Therefore,based on the mineralogical property of aggregate,the thesis carries out the research on the adhesion between aggregate and asphalt utilizing the surface free energy,the rheological property of asphalt mastics and the molecular dynamics simulation.First,the thesis collects nine different kinds of aggregates from Jilin province.The SiO₂ content,the mineral composition as well as the chemical composition are analyzed.The X-ray diffraction pattern is achieved by XRD experiment.The mineralogical indices are calculated such as the dislocation density,the micro-strain,d-spacing and the crystallite size.These indices are compared with the mechanical properties of aggregate.The crush value has a positive relevance with the dislocation density and the micro-strain.The more the defects inside the mineral,the more the dislocation density,the aggregate is more prone to crush.Then,through boiling method,the adhesion level of aggregate is evaluated.The acid aggregate is in level 2,the neutral aggregate is in level 3,the alkali aggregate is in level 4.Based on the theory of surface free energy and the rheological property of asphalt mastics,the adhesion is tested and analyzed by the value of ER and interaction parameter B.These two parameters can distinguish more accurately and precisely.The ratio between?CaO+MgO?and?SiO₂+Al₂O₃?has a good correlation with ER and B,the correlation coefficient is 0.760 and 0.833 respectively,the ration can be used in analysis.Through comparing three different methods,the method with the evaluation index of interaction parameter B is recommended based on the relativity with the ratio,which has a good reflection of the aggregate's mineralogical property.Finally,the model of aggregate is constructed according to its minerological component and the model of asphalt is constructed based on its composiiton.The interface model of aggregate and asphalt is constructed and conducted the molecular dynamics simulation.The result shows that the mineral components have influence on the interface's energy.The correlation coefficient between the simulation result with ER and B is 0.806 and 0.799 respectively,which has a relatively good accordance.