多聚磷酸改性沥青的性能及微观结构研究

发布时间：2018-02-03 17:29

本文关键词： 沥青多聚磷酸动态剪切流变仪原子力显微镜　出处：《昆明理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：在中国,随着公路建设的快速发展,沥青混凝土的需求逐年增加,沥青的使用量迅速增长。同时由于交通量和荷载的增加,普通沥青已难以满足现在道路的要求,目前已经使用多种改性剂来改善沥青的性能来满足道路需求。聚合物类改性沥青属于物理改性,存在成本高、改性设备贵、改性工艺复杂、以及储存稳定性差等缺点,制约着我国改性沥青的发展。在沥青中掺加多聚磷酸进行化学改性,可以有效的解决现有物理改性的缺点,同时多聚磷酸改性沥青成本低廉、工艺简单,具有良好的应用前景。首先为了验证多聚磷酸对云南本地使用沥青的改性作用,本文通过实验室制备了多聚磷酸改性沥青,研究了多聚磷酸的添加对基质沥青的物理性能的影响。试验结果表明,多聚磷酸的添加使基质沥青的延度下降、软化点上升、针入度下降,可以有效改善基质沥青的感温性、高温稳定性、抗老化性能等,对云南本地沥青有良好的改性效果。以上对多聚磷酸改性沥青的性能进行了初步研究,但都使用的是我国规范上采用的经验性指标,不能很准确的评价材料的性能,并且与实际路用性能的关联性也较差。为了更好的理解PPA对沥青的改性作用,本文从粘弹性力学的角度出发,研究了多聚磷酸改性沥青的粘弹性力学行为,并试图建立与实际路用性能的关联。本文通过动态剪切流变实验研究了温度及作用荷载频率对多聚磷酸改性沥青老化前后粘弹参数的影响；通过静态的多重应力蠕变恢复实验分析了多聚磷酸改性沥青老化前后的蠕变特性。实验结果表明,多聚磷酸的添加可以提高沥青的复数剪切模量(G*),增大沥青的疲劳因子(G*sinδ),减少沥青的总应变和不可恢复应变,从而增强了路面抵抗永久变形的能力；并且降低沥青对载荷的敏感度,降低老化对沥青的影响,从而提高了路面抵抗疲劳车载的能力和耐久性。材料宏观性质的改变与材料微观结构有密切关系,研究材料微观结构的变化,对理解材料的构效关系、建立宏微观尺度的关联有重要意义。本文为了研究微观下多聚磷酸对沥青的影响,采用原子力显微镜对多聚磷酸改性沥青老化前后的相图、形貌图及力-位移曲线进行了研究。结果表明,原子力显微镜是研究沥青微观结构的有力工具,多聚磷酸的添加使沥青中“蜂型”结构增多,相互连接、长大,并且白色区域面积增大,同时多聚磷酸的添加使白色区域的弹性模量增加,粘附力上升。综上所述,多聚磷酸作为一种化学改性剂,不但可以单独使用,可以很好的改善沥青的性能,还可以与其他聚合物进行复配,生产出性能更为优异的改性沥青,从而满足高性能道路的要求。原子力显微镜可以很好的观察到沥青在微观下的形貌,并可以对其微观下力学性能进行测试,为今后进行宏观性能与微观性能的关联打下基础。
[Abstract]:In China, with the rapid development of highway construction, the demand of asphalt concrete increases year by year, and the use of asphalt increases rapidly. At the same time, due to the increase of traffic volume and load. Ordinary asphalt has been difficult to meet the requirements of the current road. At present, a variety of modifiers have been used to improve the performance of asphalt to meet road needs. Polymer modified asphalt is physical modified and has high cost. The development of modified asphalt in China is restricted by the disadvantages of expensive equipment complex modification process and poor storage stability. Chemical modification is carried out by adding polyphosphoric acid into asphalt. It can effectively solve the shortcomings of the existing physical modification, at the same time, the polyphosphoric acid modified asphalt has low cost and simple process. In order to verify the effect of polyphosphoric acid on the modification of Yunnan native asphalt, polyphosphoric acid modified asphalt was prepared in laboratory. The effect of polyphosphoric acid addition on the physical properties of matrix asphalt was studied. The experimental results showed that the addition of polyphosphoric acid decreased the ductility of matrix asphalt, the softening point increased and the penetration decreased. It can effectively improve the temperature sensitivity, high temperature stability, aging resistance and so on, and has a good modification effect on Yunnan native asphalt. The performance of polyphosphoric acid modified asphalt has been preliminarily studied. However, all of them are empirical indexes used in our country, which can not evaluate the performance of materials accurately, and the relevance with the actual road performance is also poor. In order to better understand the effect of PPA on the modification of asphalt. In this paper, the viscoelastic behavior of polyphosphoric acid modified asphalt was studied from the point of view of viscoelastic mechanics. The influence of temperature and loading frequency on viscoelastic parameters of polyphosphoric acid modified asphalt before and after aging was studied by dynamic shear rheological experiment. The creep properties of polyphosphoric acid modified asphalt before and after aging were analyzed by static multi-stress creep recovery experiment. The experimental results show that the addition of polyphosphoric acid can improve the complex shear modulus of asphalt. By increasing the fatigue factor of asphalt, the total strain and unrecoverable strain of asphalt are reduced, and the ability of road surface to resist permanent deformation is enhanced. And reduce the sensitivity of asphalt to load, reduce the influence of aging on asphalt, thus improve the ability and durability of road anti-fatigue vehicle. The change of material macroscopical properties is closely related to the microstructure of material. It is very important to study the change of material microstructure in order to understand the structure-activity relationship of materials and to establish the relationship between macro and micro scale. In order to study the effect of polyphosphoric acid on asphalt. The phase diagrams, morphologies and force-displacement curves of polyphosphoric acid modified asphalt before and after aging were studied by atomic force microscope (AFM). The results show that AFM is a powerful tool for studying the microstructure of asphalt. The addition of polyphosphoric acid makes the "bee type" structure in asphalt increase, connect with each other, grow up, and increase the area of white area. Meanwhile, the addition of polyphosphoric acid increases the elastic modulus of white area. To sum up, polyphosphoric acid as a chemical modifier, not only can be used alone, can improve the performance of asphalt, but also can be mixed with other polymers. In order to meet the requirements of high performance roads, the modified asphalt with better performance can be produced. Atomic force microscope (AFM) can observe the morphology of asphalt in microcosmic and test its mechanical properties. It will lay a foundation for the relationship between macro and micro performance in the future.
【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U414

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