膜厚度对沥青流变性能的影响研究

Influence of Film Thickness on Rheological Properties of Bitumen

采用动态剪切流变仪(DSR)测试了4种沥青结合料及其短期老化产物在不同膜厚度下的流变性能.采用基于CAM模型构建的复数剪切模量主曲线分析了不同膜厚度下沥青流变性之间的差异,通过Black diagram曲线初步分析了沥青流变性随膜厚度变化的机理及影响因素,进一步提出用膜厚度指数B来量化分析沥青流变性随膜厚度变化的敏感性.结果表明:随着膜厚度的降低,沥青复数剪切模量呈现减小趋势,且此趋势因沥青种类不同而有所差异;膜厚度指数B能够很好地评价基质沥青流变性随膜厚度变化的敏感性,但因改性和老化作用改变了沥青结合料的分子结构及尺寸组成,因此对于改性和老化沥青,膜厚度指数B的适用性有所降低.

Rheological properties of four different bitumen binders and their short-term aged samples were tested under various testing gaps using dynamic shear rheometer（DSR）. Complex modulus master curves were built based on the CAM model in order to analyze the rheological differences when the gap changed. Black diagrams were applied to demonstrate the effects of film thickness on the theological properties of binders, with the affecting factors discussed. In addition, film thickness index B was proposed to describe the film thicknesses sensitivity of binder rheoiogica[ property for the quantitative analysis. The results in- dicate that, with the decrease of film thickness, complex modulus shows a decline trend for all binders tested. However, it was observed that a simple linear relationship cannot be used to depict these trends. A relationship between rheological properties and film thicknesses following the double logarithmically linear rule is established and B can be well fitted on the base bitumen binder. On the other hand, the molecular structure will be changed by modification and aging to a certain degree which may reduce the applicability of B.