乳化沥青残留物疲劳特性评价的影响因素与机理分析

Influencing factors and mechanism analysis for evaluation of fatigue characteristics of emulsified asphalt residues

基于简化黏弹性连续介质损伤(S-VECD)理论研究了乳化沥青残留物应力应变响应特征、疲劳损伤特性与疲劳寿命预估,通过傅里叶变换红外光谱仪(FTIR)、扫描电子显微镜(SEM)和原子力显微镜(AFM)等微观手段分析了乳化沥青残留物相态结构、共混改性以及疲劳损伤的影响机理。研究结果表明:普通乳化沥青残留物的损伤曲线存在交错现象,添加改性剂使得损伤曲线不再产生交错,提升了乳化沥青残留物的疲劳性能,SBR改性剂的改善效果更为显著;改性乳化沥青残留物在EN、ASTM蒸发方式下的损伤曲线较DHM蒸发方式下更平缓,表现出EN、ASTM蒸发方式下的残留物抵抗损伤能力更强;从疲劳寿命提升幅度上看,不同蒸发方式制备的普通乳化沥青残留物的最大疲劳寿命较最小疲劳寿命提升56.9%,而SBS、SBR改性乳化沥青残留物分别提升179.1%和67.8%,表明蒸发方式对改性乳化沥青残留物的巨大影响,且DHM蒸发方式下改性乳化沥青残留物的疲劳寿命均最小;添加改性剂和改变蒸发方式会引起官能团含量、胶体结构和微观粗糙度的变化;DHM蒸发方式更易使得改性乳化沥青残留物发生氧化作用,并且促使更多的沥青质的产生,使得胶团的胶溶性降低,凝胶化增强,导致乳化沥青残留物的疲劳性能降低,影响疲劳性能的评估结果;原子力显微镜试验表明通过DHM蒸发方法制备的改性乳化沥青残留物,分子结构中O^(2-)和H^(+)发生了交换缩合反应,可能产生了化学胶结结构,进而影响了乳化沥青残留物疲劳性能的准确表征与评价。

The stress-strain response characteristics,fatigue damage characteristics,and fatigue life prediction of emulsified asphalt residues were investigated based on the simplified viscoelastic continuum damage(S-VECD) theory.Microscopic approaches such as Fourier transform infrared spectrometer(FTIR),scanning electron microscope(SEM),and atomic force microscope(AFM) were adopted to study the influence mechanisms of morphology structure,blending modification,and fatigue damage of emulsified asphalt residues.Research results show that the damage curves of common emulsified asphalt residues are staggered.The addition of modifiers makes the damage curves no longer staggered,and the fatigue performance of emulsified asphalt residues is improved.Furthermore,the improvement effect of the SBR modifier is more obvious.The damage curves of modified emulsified asphalt residues prepared by the EN and ASTM evaporation methods are smoother than those prepared by the DHM evaporation method,which indicates that the residues obtained by the EN and ASTM evaporation methods have stronger resistance to damage.From the perspective of the fatigue life improvement,the maximum fatigue life of common emulsified asphalt residues prepared by different evaporation methods is 56.9% higher than the minimum fatigue life,and the SBS and SBR modified emulsified asphalt residues increase by 179.1% and 67.8%,respectively.This means that the modified emulsified asphalt residues are highly affected by the evaporation methods,and the fatigue life of modified emulsified asphalt residues is the smallest under the DHM evaporation method.Functional group contents,colloid structures,and microscopic roughness will be changed by adding modifiers and adjusting evaporation methods.The DHM evaporation method is more likely to cause oxidation of modified emulsified asphalt residues and promote the production of more asphaltenes.It decreases the solubility of micelles and enhances the gelation.As a result,the fatigue performance of emulsified asphalt residues reduces,and the evaluation result of fatigue performance is affected.AFM test results suggest that the exchange condensation reaction between O~(2-) and H~+ occurs in the molecular structure of modified emulsified asphalt residues prepared by the DHM evaporation method.In addition,chemical cementation structures may appear,and thus the accurate characterization and evaluation of fatigue performance of emulsified asphalt residues are affected.6 tabs,10 figs,32 refs.