Use of Synergistic Effect of Zinc Oxide/Expanded Vermiculite Composite to Retard Asphalt Aging Behavior
The purpose of this work was to reveal the synergistic effect of zinc oxide/expanded vermiculite(ZnO/EVMT)composite modifier,and its influence on retarding the aging behavior of asphalt;to promote research and application of new composite modifiers and corresponding asphalt pavement materials,and to improve the aging resistance and service life of asphalt pavements.First,single ZnO particles,single EVMT particles,a mixture of single ZnO and single EVMT particles(ZnO+EVMT,with the same component proportion as ZnO/EVMT composite material),and ZnO/EVMT composite were synthesized using the homogeneous precipitation method under the same preparation conditions,and their interaction characteristics were investigated.Then,the asphalt aging behavior retarded by ZnO/EVMT was revealed through evaluations of the physical properties index,rheological properties index,chemical functional group index,and molecular weight characteristics.The results show that the ZnO/EVMT composite synthesized by the homogeneous precipitation method could achieve the orderly combination of ZnO particles and EVMT at the micro-and nano-scale.Furthermore,the synergistic effect between the components of ZnO/EVMT can weaken the agglomeration of ZnO particles,and improve the dispersion of ZnO particles and their relative homogeneity with EVMT.Further,ZnO/EVMT presents higher ultraviolet light absorption capability than ZnO+EVMT and EVMT.With the introduction of ZnO/EVMT composite,the exfoliation phase structure can be formed by ZnO/EVMT and asphalt,and the ZnO/EVMT modified asphalt has good storage stability.Thus,the microstructure of the ZnO/EVMT composite and the basic properties of the modified asphalt are better than those of single component modifiers,the compound modifier,and the corresponding modified asphalt,indicating the component synergistic effect of the ZnO/EVMT composite.Therefore,the ZnO/EVMT modified asphalt exhibits lower physical and rheological properties aging indexes,less oxygen-containing functional group products,and lower large-size molecule content after laboratory short-term thermal-oxidative aging,long-term thermal-oxidative aging,and long-term ultraviolet aging.In conclusion,the ZnO/EVMT with the synergistic effects can effectively retard the aging behavior of asphalt.
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