基于菲克第二定律的再生沥青中新旧沥青扩散融合研究

Diffusion Fusion of Old and New Asphalt in Recycled AsphaltBased on Fick s Second Law

为了研究不同扩散时间、温度下新旧沥青扩散融合程度,制备了直径为25 mm,厚度为2 mm的老化沥青与新沥青双层沥青试样进行动态剪切流变试验;采用复数剪切模量G*作为双层沥青试样性能的表征参数,基于菲克第二定律理论计算了具有不同融合程度双层试样的G*理论值,从而采用迭代法并根据G*实测值计算出双层沥青试样中新旧沥青的融合程度;利用双因素方差分析评价了时间、温度对扩散融合程度的显著性。结果表明:复数剪切模量可以描述再生沥青中新旧沥青扩散融合且与新沥青掺量具有很好的线性关系,可作为性能变化的表征参数;70#基质沥青与90#基质沥青具有相同量级的扩散速率,均为10^(-7)左右,两种再生沥青的扩散速率随温度变化均呈指数增长;由双因素方差分析看出,扩散时间及温度对新旧沥青扩散融合程度都具有显著影响。

In order to study the degree of diffusion fusion of old and new asphalt at different diffusion times and temperatures,the aging asphalt with a diameter of 25mm and thickness of 2mm and new asphalt double-layer asphalt samples were prepared to carry out dynamic shear rheological tests.The complex shear modulus G*was used as the characterization parameter of the performance of double-layer asphalt samples,and the theoretical G*values of double-layer samples with different fusion degrees were calculated based on Fick’s second law theory,so that the fusion degree of new and old asphalt in double-layer asphalt samples was calculated by iterative method and according to the measured value of G*.Two-factor ANOVA was used to evaluate the significance of time and temperature on the degree of diffusion fusion.The results show that the complex shear modulus can describe the diffusion fusion of old and new asphalt in recycled asphalt,and it has a good linear relationship with the new asphalt content,which can be used as a characterization parameter for performance change.70#base asphalt and 90#base asphalt have diffusion rates of the same magnitude,both of which are around 10^(-7),and the diffusion rate of both kinds of recycled asphalt increases exponentially with temperature change.From the two-factor ANOVA analysis,it is found that the diffusion time and temperature have a significant impact on the degree of diffusion fusion of new and old asphalt.