【作者】 姚立阳；

【导师】 马勤；

【作者基本信息】 兰州理工大学 ， 材料学， 2012， 博士

【摘要】 为了改善沥青混合料路面的路用性能,采用新材料、新设备、新工艺减少沥青路面的损坏,延长其使用寿命,是改造沥青路面工业落后技术现状的重要手段。业已证明聚丙烯腈纤维作为一种新型的沥青混合料添加材料,具有强度高,吸附性强、化学稳定性及分散性好等特点,可提高路面的高温抗变形能力和低温抗裂等性能,从而延长了路面使用寿命,具有广泛的应用前景。本文就聚丙烯腈纤维在沥青混合料中的应用做了如下系统研究：第一,首先借助扫描电子显微镜观察了聚丙烯腈纤维的微观形貌,聚丙烯腈纤维长度在6mm左右,直径在18μm左右,长度和粗细程度比较均匀,横截面近似为圆形,沿纤维纵向具有粗糙且明显的纹理,端部具有比较明显的“突起”。其次,通过吸油性试验、吸水性试验和耐高温性能试验分析了聚丙烯腈纤维与沥青混合料的适用性,表明聚丙烯腈纤维的吸油性良好、吸水性较小,并且在高温处理后,聚丙烯腈纤维的微观形貌、化学成分和力学性能基本没有发生变化,表现出了与沥青混合料之间良好的相容性。第二,通过改进的锥入度试验,弯曲梁流变试验和动态剪切流变试验,分析了聚丙烯腈纤维对基质沥青胶浆性能的影响。首先,纤维的添加有效地降低了基质沥青的温度敏感性,起到了增粘增稠的作用,并且剪切强度显著提高,有效地改善了沥青胶浆的高温性能；低温下,聚丙烯腈纤维沥青胶浆的蠕变劲度提高,抗温缩变形能力增强；动态剪切流变参数G*、δ、G′、G″、G*/sin δ与温度之间具有良好的相关性,聚丙烯腈纤维的添加提高了胶浆中弹性可恢复部分所占的比例,抗车辙因子G*/sinδ显著提高,有效地改善了胶浆的高温抗永久变形能力。其次,聚丙烯腈纤维三维随机地分布于沥青胶浆之中,利用傅里叶变换红外光谱分析仪分析得知纤维与沥青之间只是简单地物理吸附或缠绕,没有发生化学组分的变化。第三,通过TRLL、CPN和AAPA三种车辙试验研究发现,聚丙烯腈纤维之间以“桥接”和“搭连”等方式三维随机分布于混合料之中,起到增粘、稳定、加筋等作用,显著地改善了沥青混合料的高温抗车辙性能,而且TRLL与和AAPA车辙试验之间的相关性更好。通过简支梁低温弯曲试验发现,由于聚丙烯腈纤维的阻裂及应力分散作用,沥青混合料的低温抗裂性能得到改善。通过浸水马歇尔试验看到,由于聚丙烯腈纤维的增粘及减小空隙率的作用,纤维沥青混合料的水稳定性能显著提高。而且聚丙烯腈纤维对沥青混合料性能改善的最佳掺量为0.3%。第四,利用伯格斯模型研究了聚丙烯腈纤维沥青胶浆和纤维沥青混合料的粘弹特性,并得到了纤维沥青胶浆和纤维沥青混合料的伯格斯模型的拟合参数；通过试验证实伯格斯模型可以较好地描述纤维沥青胶浆和纤维沥青混合料的粘弹特性的力学行为。最后,通过试验段的铺筑,获得了较好的效果,并得到了聚丙烯腈纤维沥青混合料路面施工要求,与普通沥青混合料路面施工比较干拌时间需延长10s～15s,施工温度需提高10℃～15℃。更多还原

【Abstract】 To improve road performance of asphalt mixture pavement, it is very important means that new materials, new equipments and new technology are used to reduce damages of asphalt pavement and prolong its life in the process of reforming backward technique of asphalt pavement. Polyacrylonitrile fiber as a new type of adding material has the characteristics of high strength, high absorption, chemical property stable and good dispersion. It can improve significantly high temperature resisting deformation and low temperature anti-cracking property to prolong the life of pavement. So polyacrylonitrile fiber has a good application prospect.This paper systemically studied the application of polyacrylonitrile fiber in asphalt mixture, the main content as follows:First, the morphology of polyacrylonitrile fiber was analyzed:the length and the thickness are relatively uniform, length about6mm, diameter about18μm. Its cross-section is approximated to be circular. The fiber along its length has rough and clear texture. The two ends of fiber have noticeable projections. Secondly, by oil absorbency test, water absorbency test and high temperature test, the suitability of the fiber and asphalt mixtures was analyzed. The results show that fibers have good oil absorbency and lower water absorbency. At220℃high temperature, the morphology, chemical composition and strength of polyacrylonitrile fiber remain hardly unchanged. This shows that the suitability between the fiber and asphalt mixtures is very good.Second, the influence of polyacrylonitrile fiber on performance of asphalt mortar was studied by cone penetration test, bending beam rheological test and dynamic shear rheological test. To start with, temperature sensitivity of asphalt mortar is reduced by adding fibers effectively. And fibers can play tackifying and thickening active roles in asphalt mortar. Simultaneously, the shear strength of asphalt mortar is increased clearly. So high temperature performance of asphalt mortar is improved effectively. At low temperatures, the strength and the resisting transformation of polyacrylonitrile fiber asphalt mortar are reinforced apparently. But the malleability of fiber asphalt mortar is reduced slightly. There are good relativity between rheological parameter G*、δ、G’、G"、G*/sinδ and the temperature. And the ratio of renewable elastic part of fiber asphalt mortar is increased by adding fibers. And rutting resistance factor G*/sin5of fiber asphalt mortar is raised clearly, this shows that rutting resistance performance at high temperature is improved obviously. By SEM and FTIR, it is discovered that fibers are randomly distributed throughout asphalt mortar, and physical absorption or binding happens in the interfaces between fibers and asphalt, and the chemical species of asphalt remain unchanged.Third, by three rutting tests of TRLL, CPN and AAPA, it is discovered that polyacrylonitrile fibers may improve rutting resistance performance of asphalt mixture at high temperature apparently. Polyacrylonitrile fibers distribute randomly in asphalt mixture by way of "bridging" and "the lap" and play tackifying, stabilizing and reinforcing roles.Tthere are good relativity between TRLL and AAPA. it is discovered that by beam bending test at low temperature anti-cracking performance of fiber asphalt mixture may be improved clearly because of the roles of crack resistance and stress dispersion of fibers. It is discovered that by immersion Marshall Test the performance of resisting damage of water of fiber asphalt mixture may be improved significantly because of the roles of tackifying and reducing void ratio of fibers. And the optimum containing of polyacrylonitrile fiber in asphalt mixture is0.3%.Fourth, viscoelasticities of polyacrylonitrile fiber asphalt mastic and polyacrylonitrile fiber asphalt mixture were studied using the Burgers model, and the fitting parameters of the Burgers model of fiber asphalt mastic and fiber asphalt mixture were obtained. Tests show that the Burgers model is valid to describe the mechanics behavior of viscoelasticities of fiber asphalt mastic and fiber asphalt mixture.Finally, application in test roads has received prominent effects. And the construction requirements of polyacrylonitrile fiber asphalt pavement are obtained. With the construction of normal asphalt pavement, dry mixing time of fiber asphalt mixture must extend10seconds to15seconds, and the construction temperature of fiber asphalt pavement must be increased by10degrees to15degrees.更多还原