【作者】 王佳妮；

【导师】 谭忆秋；

【作者基本信息】 哈尔滨工业大学 ， 道路与铁道工程， 2008， 博士

【摘要】 我国海拔2000m以上的面积约占国土总面积的33%,这类地区紫外辐射强度是平原地区的4-5倍。沥青紫外老化现象严重是导致沥青路面过早的破坏的主要原因之一。本文通过改进的老化设备实现了沥青野外紫外老化的室内加速模拟试验;利用流变学的手段对紫外老化后沥青的路用性能进行研究;利用红外光谱、薄层色谱等分析方法进行紫外老化机理研究,明确了沥青的紫外老化机理;在对多种改善措施性能比较的基础上,提出了紫外老化改善措施的建议。主要研究内容及成果概括如下:在深入了解室外紫外线辐照规律的基础上,对原有的紫外老化设备进行了改造,选择了更合理的紫外线辐照光源,加设了冷却和供气系统,使紫外老化系统能真实地模拟室外沥青的紫外老化;确定了室内紫外老化加速率的计算方法及室内加速紫外老化的方法。利用动态流变学的手段全面分析了紫外老化后沥青的流变性能和与石粉的交互作用。研究表明,紫外老化后沥青在使用温度范围内复合模量变大,滞后角变小,流变性变差;利用B值对不同沥青与石粉的交互作用进行了研究,试验结果表明紫外老化后二者的交互作用降低。低温流变性变差,沥青更易发生脆性破坏;中温流变性的劣化,使沥青更易发生疲劳破坏;高温流变性变差,使车辙因子增大,对沥青的高温抗车辙能力有利,三者相比较,紫外老化后以低温流变行为的变化最显著,对沥青路用性能最不利。紫外老化改变了沥青的材料性质和力学行为。老化后的沥青由柔而软的材料变成了刚而脆的材料;随着老化时间的延长,粘弹转变频率逐渐向低频移动,表明老化后的沥青在较高温度下即可发生从粘性区向弹性区的转变,在低温条件下容易发生破坏。以时温等效原理的失效温度为判断方法观察到,紫外老化后沥青的聚集态转变温度发生变化。玻璃态转化温度随沥青老化深度的增加呈升高趋势,紫外老化后沥青在较高温度下就转化为玻璃态。由于处于玻璃态的分子链段松弛时间远远大于力作用时间,因此,沥青由原来的“柔而软”变为老化后的“刚而脆”。紫外老化后聚集态的变化,是沥青力学行为转变、流变特性变差的内在原因。对紫外老化过程中各组分自由基链反应历程的研究表明,沥青的紫外老化是各族组分共同参与的紫外光氧化反应,饱和分不仅参与了老化反应,并对芳香分和胶质的光氧化反应起促进作用,是沥青紫外老化反应的重要物质。饱和分含量高的沥青紫外老化更强烈,老化后沥青流变性的劣化更显著。紫外老化过程中,胶质沥青质之间产生较强缔和作用,这种缔和在宏观上对应沥青质的聚集沉淀,随着紫外老化反应的进行,沥青由溶胶向凝胶、由胶体向固体转变。沥青胶体结构的转变和沥青质的聚沉是导致沥青在紫外老化后发生聚集态变化的本质原因。最后,本文研究了改善沥青抗紫外老化能力的措施。通过不同方案的路用性能比较和验证,发现基质沥青添加改性剂比单独使用基质沥青具有更强的抗紫外老化能力;改性剂SBR的抗紫外老化效果优于SBS;紫外吸收剂、抗氧化剂及光稳定剂均具有一定的抗紫外老化能力;试验结果表明光稳定剂与SBR改性沥青联合使用时性能优于其它抗老化剂与改性剂联用,具有更好的抗紫外老化性能。更多还原

【Abstract】 The area, about 33% of the total land area of China,is at altitude of 2000m above, in which, the UV radiation intensity is almost 4-5 times of plain areas.Severely ultraviolet aged asphalt is one of the most important reasons for early damage of asphalt pavement. In this paper, indoor accelerated simulation of outdoor ultraviolet aging of asphalt is carried out by improving original aging equipment; road performance of ultraviolet aged asphalt is studied based on rheology; ultraviolet aging mechanism is analyzed by means of infrared spectrum and thin-layer chromatography; in comparison of performance of multiple improvement measures, suggestions on anti-ultraviolet aging is proposed. All research works in the paper are outlined as following:In order to simulate veritably the outdoor ultraviolet aging, the original uv aging equipment is improved, selecting more reasonable ultraviolet radiation lamp and adding cooling and gas supply systems; in addition, the calculation method of indoor ultraviolet aging velocity gradient and the method of indoor accelerated ultraviolet aging are determined.The rheological properties of ultraviolet aged asphalt and its interaction capability with aggregate powder have been comprehensively analyzed based on dynamic rheology. Studies have shown that the complex modulus of ultraviolet aged asphalt increases, phase angle decreases and the low temperature deformability has deteriorated, so it is more susceptible to brittle cracking; what’s else, increase of rutting factor indicates that high temperature performance of ultraviolet aged asphalt has been improved in different degrees; Studies on interaction between asphalt and powder show that the interaction capability declines catholically after ultraviolet aging, no influence of asphalt type, lithology and powder size.Material properties and mechanical behaviors of asphalt have been altered by ultraviolet aging.Asphalt becomes more rigid and brittle after 220h ultraviolet aging; with aging time prolonged, on one hand, viscosity-elasticity transformation frequency declines and it indicates that the transition temperature increases at which ultraviolet aged asphalt is transformed from viscosity region to elastic region and therefore asphalt is more sensitive to low temperature cracking. On the other hand, the decrease of phase angle implies proportion of viscosity and elastic composition has been altered and the viscosity composition declines, consequently ,it is hard for asphalt to relax stress resulting from temperature and load and then low temperature cracks appears. Moreover, with aging time prolonged, glass transfer temperature increases, and it indicates that the relaxation time of molecular chain segment in glass state is far more than force action time, and this explains why ultraviolet aged asphalt is susceptible to brittle failure at low temperature.Ultraviolet aging is oxidation reaction in which aromatic and resin are main materials and saturated fragrance promotes the ultraviolet oxidation reaction of aromatic and resin. After ultraviolet aging, saturated fragrance produces small amount of resin and asphaltene, aromatic transforms into resin and asphaltene and resin and asphaltene transform into asphaltene.Studies on effect of ultraviolet aging on colloidal structure stability have shown that a strong combination, which is presented as aggregation and precipitation of asphaltene in macroscopic view, is produced between resin and asphaltene. In course of ultraviolet aging,asphalt changes from sol to gel,from colloid to solid. In IR spectra comparison of ultraviolet aged and unaged asphalt, ultraviolet aging characteristic peak is found and it is pointed out that the performance of different asphalts tends to be uniform after a period of aging. Researches on consistency and reaction degree of group composition show that saturated fragrance has a strong effect on ultraviolet aging performance of asphalt. Asphalt with a higher content of saturated fragrance ages more strongly and the rheology deterioration is more obvious.Through road performance comparison and verification of various schemes, it is found that modified asphalt behaves a stronger anti-ultraviolet aging ability than base asphalt; anti-ultraviolet aging effect of SBR is better than SBS;ultraviolet absorbent,antioxidant and light stabilizer all posses anti-ultraviolet aging ability; tests have proved joint use of light stabilizer and SBR show better anti-ultraviolet aging ability than combination of other anti-aging agent and modifier.更多还原