再生剂在老化沥青中扩散行为的多尺度研究

Multi-scale study on the diffusion behavior of regenerant in aged asphalt

【目的】深入了解再生剂在老化沥青中的扩散行为及影响因素。【方法】以紫外老化和热氧老化沥青为研究对象,通过动态剪切流变(dynamic shear rheological,DSR)试验研究了再生剂在老化沥青中的扩散规律,从而得到表征扩散程度的相对指标--复数模量恢复率,并分析了老化方式、扩散温度、扩散时间对扩散程度的影响。在微观层面通过原子力显微镜(atomic force microscope,AFM)和傅里叶变换红外光谱(Fourier transform infrared spectroscopy,FTIR)及热重(thermogravimetric,TG)试验对再生剂-老化沥青扩散体系进行测试,并对宏微观指标进行皮尔逊相关性分析。【结果】DSR试验结果表明,再生剂在老化沥青中存在扩散梯度;在相同的扩散条件下,再生剂在紫外老化沥青中的扩散程度比在热氧老化沥青中的大;扩散温度越高,扩散时间越长,再生剂的扩散现象越明显。微观试验结果表明,随着扩散进程的持续,再生剂对老化沥青黏弹性能有较好的恢复,使老化沥青内部的轻质组分得到补充,从而恢复沥青性能。皮尔逊相关性分析结果表明,宏微观指标具有良好的相关性。【结论】采用宏微观相结合的试验方法来研究再生剂在老化沥青中的扩散行为是一种可行的方法。

[Purposes]This study aims to understand the diffusion behavior and influencing factors of the regenerant in the aged asphalt.[Methods]Using the ultraviolet aged and thermal oxygen aged asphalt as the research objects,the dynamic shear rheological(DSR)test was used to study the diffusion pattern of rejuvenators in aged asphalt to obtain a relative index characterizing the degree of diffusion.Moreover,the complex modulus recovery,which is a measure of the degree of diffusion,and the influence of aged mode,diffusion temperature,and diffusion time on the degree of diffusion are analyzed.At the micro level,the regenerant-aged asphalt diffusion system was tested by atomic force microscopy(AFM),while Fourier transform infrared spectroscopy(FTIR)and thermogravimetric(TG)test,and the Pearson correlation analysis was performed on the macro and micro indicators.[Findings]DSR results show that there is a diffusion gradient of the regenerant in the aged asphalt.Under the same diffusion conditions,the degree of diffusion of the regenerant in the ultraviolet aged asphalt is greater than that of the thermal oxygen aged asphalt.The higher diffusion temperature and the longer the diffusion time,the more obvious the diffusion phenomenon of the regenerant is.The microscopic test results show that with the continuation of the diffusion process,the regenerant can better restore the viscoelastic performance of the aged asphalt.Consequently,the light components inside the aged asphalt can be replenished,and the performance of the asphalt is restored.The results of Pearson correlation analysis show that the macro and micro indicators have good correlation.[Conclusions]It is a feasible method to study the diffusion behavior of regenerant in aged asphalt by combining macro and micro test methods.