【作者】 付玉；

【导师】 吴少鹏；

【作者基本信息】 武汉理工大学 ， 材料学， 2010， 博士

【摘要】 随着交通量、交通荷载的不断增加,现代交通对沥青混凝土路面的性能要求越来越高。提高沥青的耐老化性能,延长沥青混凝土路面的使用寿命是其中极为重要的一环。基于层状硅酸盐与聚合物形成的纳米复合结构可有效改善聚合物的耐老化性能,本研究采用纳米蒙脱土改性剂对沥青进行改性,制备纳米蒙脱土改性沥青,并分别对纳米蒙脱土改性沥青及其混合料的老化性能进行深入研究,分析了纳米蒙脱土粉末的掺入对沥青及沥青混合料的路用性能和抗老化性能的影响规律,为纳米蒙脱土改性沥青在沥青混凝土路面工程中的应用提供了理论依据。本论文首先采用三大指标及粘度试验表征了蒙脱土对沥青老化前后技术性能的影响,研究结果表明：当蒙脱土掺量<3%时,随着蒙脱土的加入,沥青的软化点和粘度增大,针入度减小,延度降低,蒙脱土对沥青的高温性能有明显的改善作用；老化后,随蒙脱土用量的增加,沥青的软化点增量及老化指数减小、残留针入度比增大、残留延度值增大,表明纳米蒙脱土可以较好地改善沥青的耐老化性能,且改性沥青老化后的抗低温开裂性能提高。第二,温度扫描和频率扫描试验结果表明：老化使基质沥青90#和蒙脱土改性沥青的复合模量增加,相位角降低；与基质沥青相比,当纳米蒙脱土掺量<3%时,改性沥青短期老化后具有较低的复合模量和较大的车辙因子,说明其具有良好的抗老化性能和高温抗形变的能力；当纳米蒙脱土掺量增加到5%时,能显著减少沥青老化过程中的硬化程度,有效改善沥青的抗低温开裂性能,其改善效果在低频时表现较为明显。第三,蠕变加载试验结果表明：老化沥青加载总变形随着纳米蒙脱土粉末掺量的增加而增加,5%层状硅酸盐蒙脱土的掺入能降低老化沥青的劲度模量,即掺纳米蒙脱土粉末能有效增强沥青的抗老化性能；-10℃时,沥青老化后的剪切蠕变模量随蒙脱土掺量的增加而减小,20℃时,剪切蠕变模量随蒙脱土掺量的增加而增加,表明掺蒙脱土能够改善沥青的低温抗开裂性能和提高沥青长期老化后的高温抗剪性能。第四,3%掺量的纳米蒙脱土改性剂显著提高了老化后沥青混合料的马歇尔稳定度、劈裂强度、抗水损害性能和抗压抗拉强度；在同样的温度条件下,沥青混合料的间接拉伸破坏时间随加载速率的增大而急剧减小,抗拉强度增大；在同样的应变加载速率下,沥青混合料的间接拉伸强度随温度的升高而明显降低。第五,沥青混合料的疲劳寿命均随着加载应力的增加而降低,疲劳次数随老化程度的增加而减小；经纳米蒙脱土改性后老化沥青混合料的间接拉伸模量减小,老化程度降低；老化后,纳米蒙脱土粉末改性沥青混合料的疲劳次数大于基质沥青混合料的疲劳次数,表明纳米蒙脱土的掺入能够提高沥青混合料老化后的耐疲劳性能。更多还原

【Abstract】 It is urgent for the high-quality asphalt pavement in modern traffic with the increasing of the traffic volume and traffic load. Therefore, it is significant to improve the aging resistance of the asphalt binders in order to prolong the service life of asphalt pavements. Some researchers found out that nano-composite based on the layered silicate and polymer can effectively improve the aging resistance of the polymers. This paper aims at manufacturing nano-meter montmorillonite modified asphalt and researching the aging characteristics of nano-meter montmorillonite modified asphalt and asphalt mixtures. It also studied the influences of nano-meter montmorillonite on the pavement performances and the aging resistance of the modified asphalt and asphalt mixture. These researches provide theoretical basis for the application of the nano-meter montmorillonite modified asphalt in the asphalt pavement engineering.Firstly, this paper researched the influences of nano-meter montmorillonite on the aging properties of asphalt with three indexes and viscosity. Experiment results show that the softening point and viscosity of asphalt increases, nevertheless, both the penetrate degree and ductility of asphalt decreases when the montmorillonite content is less than three percents, which indicates that the montmorillonite can improve the properties of the asphalts at the high temperatures significantly. Investigation of aging asphalt shows that the softening point increment and VAI of asphalt are decreasing with the increasing of the content of the montmorillonite, but both the residual penetration ratio and residual ductility value are increasing. The results show that nano-meter montmorillonite modified asphalt has a better ageing resistance and the crack-resistant is better than the base asphalt.Secondly, the temperature and frequency sweep tests showed that the composite modulus of base bitumen and nano-meter montmorillonite modified bitumen were increasing and the phase angle was decreasing with the aging process. Compared to the base bitumen, nano-meter montmorillonite modified bitumen had lower complex modulus and higher rut factor when the montmorillonite content was less than three percents, which showed a good aging resistance and the high temperature stability. The hardening degree of asphalts in aging process decreased significantly when the montmorillonite content increased to five percents. Under this circumstance, it can effectively improve the low temperature crack resistance of asphalt especially at the low frequency. Thirdly, the creep loading test showed that the deformation of asphalts loaded were increasing with the increasing contents of the nano-meter montmorillonite powders.It found that the stiffness modulus of the aging asphalt decreased with the the five percents contents of the layered silicate montmorillonite, which indicates that the nano-meter montmorillonite power can effectively improve the aging resistance of the asphalts. The modulus of shear creep decreased with the increasing contents of the montmorillonite at minus ten centigrade, while at twenty centigrade it increased, which indicated that the montmorillonite can improve the low temperature crack resistance of the asphalts and the high temperature shear resistance of asphalts in the long-term ageing.Fourthly, the Marshall stability, splitting strength, water resistance and tensile or compressive strength of aged asphalt mixture sharply increased while adding three percents montmorillonite modifier. At the same temperature, the indirect tensile fracture time of asphalt mixture decreased with the increase of loading speed, while the tensile strength increased. At the same applied strain rate, the indirect tensile strength sharply decreased with the rise of the temperatures.Fifthly, it founded that the fatigue life of asphalt mixture decreased with the increasing loading stress. Meanwhile, there is a decrease in fatigue cycle numbers when the aging time continued. Both the indirect tensile modulus and the degree of aging decreased while aged asphalt mixture was modified by nano-meter montmorillonite. Experiment results show that the nano-meter montmorillonite can improve the fatigue strength of aged asphalt mixture effectively.更多还原