基于现代物相技术的沥青结合料热老化机理研究

发布时间：2019-05-30 06:10

【摘要】：沥青老化导致路用性能劣化,是影响耐久性的重要因素。本文基于傅里叶红外光谱试验(FTIR)、热分析试验(DSC、TG)和质谱试验(MS)的现代物相技术,对沥青结合料老化前后的试样进行测试,分析沥青老化过程中微观结构的变化与宏观性能指标和路用性能的联系,揭示沥青结合料的热老化机理,为提高沥青抗老化性能提供理论基础。以西石化70#沥青为基质沥青,制备四川天然岩沥青掺量分别为2%、4%、6%和8%的改性沥青,并试验得到这五种沥青结合料三种状态(原样、短期老化和长期老化)的试样,对试样进行沥青三大指标试验、动态剪切流变试验(DSR)、动态频率扫描试验、傅里叶红外光谱试验、热分析和质谱试验。参照有机化合物基团振动频率,对红外光谱试验数据进行定性和定量分析。分析五种原样沥青及每种沥青老化后的红外光谱图,定性地推测天然沥青改性的机理和老化过程中发生变化的分子结构;对比分析老化过程中羰基指数(CI)、亚砜指数(SI)、甲基指数(MI)和吸光度(fa)等参数,判断老化的程度和对应官能团或组分的转化情况,揭示沥青的热老化机理。对老化前后DSC、TG和MS联用试验数据进行处理,综合图中吸热峰的位置、质量损失速率和离子流强度等信息,判定沥青的高温稳定性,并与红外光谱分析中的结论相互对应。研究认为,沥青的老化符合自由基反应历程,短期老化以“脱氢型”氧化反应为主,伴随轻质组分挥发,长期老化主要是“吸氧型”氧化反应,生成大量的羰基和亚砜基;老化后,软化点、复数剪切模量和抗车辙因子增加,针入度和相位角减小,沥青的高温稳定性提高,与碱集料间的黏附性增强,感温性降低,低温抗裂性能下降;残留针入度比和短期老化前后的热焓比可作为预测沥青长期老化程度的一种手段,热焓值可以判定老化前后结合料的胶体结构稳定性。现代物相联用技术对于分析结合料老化前后的高温和黏附性结论一致,对确定改性剂的最佳掺量也有一定帮助,可以应用于沥青结合料的相关研究中。
[Abstract]:Asphalt aging leads to deterioration of road performance, which is an important factor affecting durability. In this paper, based on the modern phase technology of Fourier transform infrared spectroscopy (FTIR),) thermal analysis test (DSC,TG) and mass spectrometry test (MS), the samples of asphalt binders before and after aging were tested. The relationship between the change of microstructure and macro performance index and road performance in the process of asphalt aging is analyzed, and the thermal aging mechanism of asphalt binder is revealed, which provides a theoretical basis for improving the anti-aging performance of asphalt. The modified asphalt containing 2%, 4%, 6% and 8% of Sichuan natural rock asphalt was prepared by Xizhihua 70# asphalt as matrix asphalt, and three states of the five kinds of asphalt binders were obtained. In the samples of short-term aging and long-term aging, three indexes of asphalt, dynamic shear flow test (DSR), dynamic frequency scanning test, Fourier transform infrared spectroscopy test, thermal analysis and mass spectrometry test were carried out. According to the vibration frequency of organic compounds, the infrared spectrum test data were qualitatively and quantitatively analyzed. The infrared spectra of five kinds of original asphalt and each kind of asphalt after aging were analyzed, and the modification mechanism of natural asphalt and the molecular structure changed during aging were speculated qualitatively. The parameters such as carbonyl index (CI), sulfoxide index (SI), methyl index (MI) and absorbance (fa) during aging were compared and analyzed. The degree of aging and the transformation of corresponding functional groups or components were judged and the thermal aging mechanism of asphalt was revealed. The data of DSC,TG and MS test before and after aging were processed. The position of endothermic peak, mass loss rate and ion current intensity in the diagram were synthesized to determine the high temperature stability of asphalt, which corresponds to the conclusions in infrared spectrum analysis. It is considered that the aging of asphalt accords with the free radical reaction process, and the short-term aging is mainly "hydrogenated" oxidation reaction, accompanied by the volatilization of light components, and the long-term aging is mainly "oxygen-absorbing" oxidation reaction, resulting in a large number of carbonyl and sulfoxide groups. After aging, the softened point, complex shear modulus and rut resistance factor increase, penetration and phase angle decrease, the high temperature stability of asphalt increases, the adhesion between asphalt and alkali aggregate increases, the temperature sensitivity decreases, and the crack resistance at low temperature decreases. The residual penetration ratio and the enthalpy ratio before and after short-term aging can be used as a means to predict the long-term aging degree of asphalt, and the enthalpy value can be used to determine the colloidal structure stability of the binder before and after aging. The modern phase coupling technique is consistent in the analysis of high temperature and adhesion of binders before and after aging, and is also helpful to determine the optimum content of modifier. It can be used in the research of asphalt binders.
【学位授予单位】：长安大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U414

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