【作者】 黄文通；

【导师】 徐国元；

【作者基本信息】 华南理工大学 ， 道路与铁道工程， 2014， 博士

【摘要】 天然岩沥青是一种优质的路用沥青改性剂，能有效地改善沥青材料及其混合料的路用性能。深入研究北美岩沥青的细观结构、改性机理、粘弹特性以及路用性能，对提高沥青路面的使用性能和北美岩沥青改性剂的推广应用，具有重要的意义。在前人的基础上，本文采用理论分析、室内综合参数测定试验研究、以及北美岩沥青试验段实体工程的现场铺筑和现场检测分析相结合的方法，对北美岩沥青及其混合料路用性能进行系统全面的研究，以期进一步提高北美岩沥青的作用属性认识水平和工程应用水平。主要研究内容与成果如下：（1）通过对不同掺量北美岩沥青制备岩沥青改性沥青的系统试验研究，分析了北美岩沥青对基质沥青感温性、高温性、低温性、耐久性的影响，结果表明北美岩沥青能明显改善沥青的感温性、高温稳定性和抗老化性能，但对沥青的低温性能无改善作用。进一步地，综合采用荧光显微镜、元素分析、红外光谱、差示扫描量热、凝胶渗透色谱、核磁共振波谱、表面自由能等细观分析测试手段，探寻北美岩沥青的作用机理及改性效果，深层次地揭示了北美岩沥青有效降低沥青温度敏感性、提高沥青高温稳定性、提高沥青抗老化能力、改善沥青黏附性能和水稳定性能的根本原因。北美岩沥青对基质沥青的改性作用主要表现是：①北美岩沥青与基质沥青混合后，岩沥青颗粒分散存在于沥青中，沥青与岩沥青颗粒相互包容，颗粒表面包有沥青，而沥青又渗透于岩沥青颗粒中，形成一种彼此交错的两相分散结构，这种结构决定了北美岩沥青改性沥青具有良好的流变性能和热储存稳定性能。经过北美岩沥青改性后的沥青的氢碳摩尔比减少，芳碳率提高，沥青的芳香组分比例增大，胶质比例减少，沥青质量得到很大提升。②北美岩沥青对基质沥青的改性不仅仅是北美岩沥青在基质沥青中简单分散的物理改性，而是存在化学键明显的减弱或消失，即北美岩沥青对基质沥青的改性可能存在一定程度的化学改性作用，也就是说北美岩沥青对基质沥青可能存在物理改性和化学改性的双重改性作用。北美岩沥青将-OH羟基峰带入到基质沥青中，产生新的官能团，该官能团使沥青的黏附性增强；同时，北美岩沥青将O-Si-O带入到基质沥青中，使沥青内聚力增强，软化点升高，延展性降低。③北美岩沥青的掺入能增大基质沥青的分子量，提高分子间相互作用力，使沥青软化点升高，针入度降低，粘度增加，深层次揭示了北美岩沥青改善基质沥青高温稳定性的原因所在。由于北美岩沥青的选择性吸附及溶胀作用使基质沥青的组分构成不再连续，岩沥青改性沥青的吸热量下降，其聚集态转化数量减少，沥青的分子间作用力增强，状态稳定，受温度影响小，从而揭示了北美岩沥青改善沥青感温性的原因所在。④北美岩沥青和基质沥青之间不是单纯的物理作用，还发生了部分交联反应，导致改性沥青的烷基取代基种类减少。基质沥青中烷基取代基的长度较大，容易在老化过程中发生失氢或碳链断裂，从而影响沥青的老化性能。然而，随着北美岩沥青的加入增加了改善沥青抗老化性能的可能性。⑤将北美岩沥青掺入基质沥青中，沥青与水的接触角增加，沥青的憎水性增强，表面自由能降低，沥青与集料的黏附性增强，表明北美岩沥青能改善基质沥青的抗水损害性能。北美岩沥青中氧、氮、硫等杂原子含量较高，这些杂原子都是极性很强的官能团，能够在岩石表面产生强吸附力，其吸附自由能以及在岩石表面的吸附量，均比基质沥青高出数倍，显著提高集料的抗剥落性和粘附性。（2）动态剪切流变仪温度扫描试验研究揭示：北美岩沥青改性沥青的车辙因子G*/sinδ提高、动粘度η增大，正切损失tanδ减小，疲劳因子G*sinδ增大，沥青的高温抗车辙性能得到明显改善，疲劳性能有所降低。沥青胶浆温度扫描结果表明，北美岩沥青的最佳掺量为12～15%。掺入北美岩沥青后，沥青的PG高温等级升高，北美岩沥青掺量每增加3%，PG高温等级基本上升1个等级；沥青的蠕变劲度S增大，蠕变速率m值变小，沥青的松弛能力有所降低，掺量9%～18%的北美岩沥青改性沥青PG低温等级比基质沥青降低了一个等级。（3）“干法”添加工艺获得的混合料的高温性能和水稳定性能优于“湿法”添加工艺。北美岩沥青粉末的加工粒径会影响沥青混合料的体积指标和路用性能，粒径越细，成型混合料更容易击实，也能节省沥青，用其改性后的混合料性能更优。（4）在相同的集料、矿料级配与拌和工艺下，对比分析了不同掺量北美岩沥青改性混合料以及使用不同沥青改性剂的混合料路用性能，研究结果表明，北美岩沥青能够显著改善混合料的高温稳定性能和水稳定性能，但会降低混合料的低温抗裂性能。（5）采用四点弯曲试验方法在应变控制模式下和应力控制模式下，对北美岩沥青改性沥青混合料的疲劳性能进行系统的试验研究。研究结果表明，北美岩沥青能明显提高混合料的疲劳寿命。疲劳寿命预测模型表明，北美岩沥青改性沥青混合料的疲劳寿命与应变水平具有十分良好的线性关系，应变水平越高，混合料疲劳寿命越短。基于本研究成果设计与铺筑的北美岩沥青试验段实体工程，验证了北美岩沥青的优良使用效果。北美岩沥青运输储存方便，使用工艺简单，生产及施工工艺与常规沥青混合料工艺一致，无需增加昂贵的机械设备，也无需改变拌和生产流程。本文研究成果对于提高北美岩沥青路面的设计与施工水平，具有理论参考与工程应用指导的作用。更多还原

【Abstract】 Natural rock asphalt is an effective asphalt modification for pavement asphalt, which canimprove the pavement properties of asphalt and mixtures greatly. To improve the performanceof asphalt pavement and expand the use of rock asphalt modification, it is very important tostudy the microstructure, modified mechanism, viscoelastic behavior and pavement propertiesof North American rock asphalt. Based on prevous study carried out by former researchers,this article uses theorectical analysis, experimental study, and on-situ test and analysis toinvestigate the performance and properties of North American rock asphalt and mixture,which help improve the knowledge of properties and application of rock asphalt. The maincontent and results are as follows:(1)Based on the systematic experiments of modified rock asphalt made by mixing certainamounts of North American rock asphalt and base asphalt, analyzing the influence of NorthAmerican rock asphalt on several properties of base asphalt, such as temperature susceptibility,high temperature properties, low temperature properties and durability. The test results showthat North American rock asphalt can improve all the properties of base asphalt above exceptthe low-tem properties.Several micro-analysis methods, fluoresence microscopy method, elemental analysismethod, infrared spectrum method, differential scanning calorimetry method, nuclearmagnetic resonance spectrum method and surface free energy method, are carried out toinvestigate the function mechanism and effect that North American rock asphalt has on baseasphalt, it deeply reveals the reasons that North American rock asphalt can improve all theproperties of base asphalt, including temperature susceptibility, high temperature properties,durability, absorbability of asphalt which help stick the aggregates and anti moisture damagecapacity. This modified influence that North American rock asphalt has on base asphalt are:①I n the combination ofNorth American rock asphalt and base asphalt, the particles of rockasphalt disperse in the mixed asphalt, the mixed asphalt and the rock asphalt particles blendwith each other, the rock asphalt particles are surrounded by asphalt and asphalt permeatesinto the rock asphalt particles, thus an interlocked two phases structure can be formed. Thiskind of structure determines a good rheological property and good thermal storage stability ofmodified rock asphalt. After modification, decrease of Hydrogen and Carbon molar ratio,increase of aromatic-carbon ratio and aromatic proportion, decrease of colloid proportion,improvement of asphalt quality.②The modification ofNorth American rock asphalt onbase asphalt is not only a physical modification about simple dispersion of rock asphalt in base asphalt, but also a significant reduction or disappear of the chemical bond, which isprobable the chemical modification of North American rock asphalt on base asphalt to somedegree. In other words, the North American rock asphalt has a double modifying function onbase asphalt, physically and chemically. The North American rock asphalt bring the peak ofthe-OH hydroxyl to the base asphalt, forming new a functional groups which enhanceasphalt’s adhesion ability, meanwhile, the North American rock asphalt bring O-Si-O to baseasphalt, enhancing the cohesion, increasing softening point and decreasing the extensibility.③The North American rock asphalt can increase base asphalt’s molecular weight, improvethe intermolecular force, leading to a higher softening point, a lower penetration and a betterviscosity, thus exposing why the North American rock asphalt can improve the hightemperature stability of base asphalt. As the selective adsorption and the swelling effect makebase asphalt’s component formation intermittent, decrease of modified rock asphalt’s heatabsorption, as well as the quantity of aggregation transformation, and the intermolecular forcewill be enhanced, which make asphalt a steady state and a weak effect of temperature,exposing how the North American rock asphalt can improve the temperature sensitivity ofbase asphalt.④T heNorth American rock asphalt and the base asphalt have not only physicaleffects, they also bring about crosslinking reaction partly, decreasing the alkyl substitutionspecies. The alkyl substitution of base asphalt has greater length, so the hydrogen or carbonstrand breaks occur easily in the aging process, which affect asphalt aging property. However,the North American rock asphalt can increase the possibility of improving asphalt’s anti-agingproperties.⑤increase of contact angles among asphalt and water, increase of hydrophobicity,decrease of surface free energy, increase of absorbability of asphalt which help stick theaggregates, great improvement of anti moisture damage capacity. The North American rockasphalt has a great amount of oxygen, nitrogen, sulfur and other heteroatom, they are allfunctional groups which have strong polarity, forming a higher adsorbability to the rocksurface, they have greater adsorption free energy and capacity than the base asphalt, whichcan significantly improve the anti-stripping capacity and the adhesion ability of aggregates.(2)As the temperature scanning test of modified asphalt shows, the modified asphalt hasan higher rutting factor G*/sinδ, a larger dynamic viscosity η, a smaller tangent loss tanδ, abigger fatigue factor G*sinδ. The high temperature anti rutting properties of modified asphalthas been greatly improved, while the fatigue properties of the asphalt drop a little bit. Theasphalt mucilage temperature scanning shows that the optimal amount of addition (rockasphalt) is12~15%. The asphalt modified by North American rock asphalt has an higher PGhigh temperature level, the PG high temperature level will basically rise one grade when the North American rock asphalt contents for each additional3%. The modified North Americanrock asphalt has an bigger creeping stiffness(S), a smaller creeping rate(m values), a littledropping of the relaxation ability. The PG low temperature level of modified asphaltcontented with9%to18%North American rock asphalt only has one grade lower thanasphalt.(3)Dry process adding method of North American rock asphalt mixture at hightemperature performance and water stability performance is better than the wet processadding method. The powder processing size of North American rock asphalt will affect theasphalt mixture volume indexes and pavement performance, easier compacted mixture andbetter mixture properties under the smaller powder size of North American rock asphalt. Itcan also save the modified asphalt.(4)Investigation is carried on modified asphalt made by the same aggregates, grade ofore materials and mixing process but different additional rock asphalt. The results shows thatrock asphalt can improve the high temperature stability and water stability, while it has anegative influence on anti cracking properties in low temperature.(5)Using four-point bending test to investigate fatigue properties of modified asphaltunder strain controled model and stress controled model, it shows that North American rockasphalt can greatly increase the fatigue life of mixed asphalt. The prediction model of fatiguelife shows that it has good linear relationship between fatigue life of modified asphalt mixtureand strain level, lower fatigue life under higher strain level.The design of the modified asphalt and successful application of modified asphalt showthat the North American rock asphalt has high the modification quality. With the easytransportation, simple and standard production process of the North American rock asphalt,this asphalt is of high applicable value. The results of this study has improved the the rockasphalt pavement design and its construction level, and also owns a guidance for theoreticalreference and engineering application.更多还原