| The adhesion of asphalt and aggregate in asphalt mixture is an important factor that directly affects the mechanical properties,high temperature stability,low temperature stability and water stability of asphalt mixture.Studying the effect of asphalt modifier on the adhesion properties of petroleum asphalt has great important academic significance meaning and application prospect to improve the adhesion of asphalt and aggregate and improve the road performance of asphalt mixture.Firstly,matrix asphalt(Qilu 70#A),LM-S modifier and Chunfeng vacuum residue(CFVR)were selected as the major research subject and measured their basic properties.The saturate,aromatic,resin and asphaltene were separated and characterized and their structural parameters and average molecular structural formula were confirmed through advanced instrumental analysis methods and improved Brown-Ladner method.At the same time,according to the technical indexes of SBS and sulfur,constructed their average molecular structural formulas.Determined the composition of aggregate powder by XRD analysis and constructed its crystal model.Secondly,we used Materials Studio software to construct the 3D molecular model of each component.Based on the proportion of each component,establish the matrix asphalt model and modified asphalt model.Then introduced the crystal structure of aggregate and constructed different asphalt-aggregate model systems.Calculated the interfacial adhesion work of asphalt and aggregate in each system to characterize the adhesion properties of asphalt and aggregate after molecular dynamic simulation,and the interfacial adhesion work was queued as:LM-S(20%)modified asphalt>SBS(5%)modified asphalt>matrix asphalt(Qilu 70#A)>sulfur(5%)modified asphalt>CFVR(20%)modified asphalt.Thirdly,we verified the simulation results by micro structure of asphalt-aggregate system and the coverage rate of asphalt to aggregate which was determined by hot-water dissolution method.The coverage was queued from high to low as:LM-S(20%)modified asphalt>SBS(5%)modified asphalt>matrix asphalt(Qilu 70#A)>sulfur(5%)modified asphalt>CFVR(20%)modified asphalt,which was consistent with the simulation results.It shows that LM-S modifier can significantly improve the adhesion of asphalt and aggregate.The feasibility of using molecular simulation to evaluate the adhesion of asphalt to aggregate was also verified.At last,carried out different road performance test of asphalt mixture to evaluate the road performance of LM-S modified asphalt mixture.The results show that the high temperature stability,low temperature stability and water stability of the LM-S modified asphalt mixture have been improved.Moreover LM-S modified asphalt mixture was applied to pavement construction and its actual road performance was preliminarily investigated.The results show that all the detection indexes in the early stage can meet the technical requirements of relevant specifications,and further tracking and investigation are still needed in the later period. |
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