【作者】 马慧莉；

【导师】 程永春；

【作者基本信息】 吉林大学 ， 道路与铁道工程， 2013， 博士

【摘要】 沥青粘结料是由细集料和沥青胶浆粘结组成。粘结胶浆由沥青胶浆和矿粉填料组成。由于粘结胶浆中含有微细矿粉填料颗粒，所以在一定程度上可以把粘结胶浆作为颗粒填充复合材料处理。微细颗粒的不规则形状和分布特征也会影响沥青粘结胶浆的力学性能。由于受到诸多因素的影响，沥青粘结胶浆的宏观性能具有随机不确定性。在进行胶浆性能试验时由于成型方式的不可逆，使得胶浆某些测试指标呈现较大的随机性，这主要是由内部结构的随机分布所导致的。而采用细观力学研究方法不仅能够实现沥青胶浆内部结构的重构，还能准确分析沥青粘结胶浆和沥青粘结料的破坏机理和粘弹性变形特性。在试验测试方面，常规的试验测试均是从唯像学的角度对混合料或粘结料进行的唯像测试分析，材料内部结构的随机性使得混合料内部结构的特性与宏观尺度的指标评价存在很大差异。且由于受分析工具条件的限制，基于现象的经验方法，需要大量的试验，采用宏观指标评价研究沥青混合料的性能时，需要消耗巨大的人力、财力和物力，并且测试结果的变异性较大，再现性差。而采用细观力学分析方法不仅避免了大量的试验，而且能够从细观尺度深入分析胶浆内部力学反应。可见对胶浆细观结构的分析是研究沥青混合料材料破坏特征的前提条件。利用细观建模方法对沥青胶浆结构进行模型重构，结合理论和试验成果建立真实的物理模型，进而揭示出沥青胶浆细观结构变化引起的宏观响应，具有重要的理论意义和工程应用前景。本文结合国家自然科学基金项目(51278222)“基于数字图像处理技术的沥青混合料各向异性特性研究”，探讨分析了填料颗粒对沥青胶浆性能的影响规律，主要进行了以下工作：1.采用高速剪切搅拌的方法得到了有效的分散填料颗粒，制备了性能一致的沥青胶浆。利用激光粒度分析法快速准确的分析填料的级配组成，为矿粉等填料颗粒的级配测定提供了一个快捷有效的测定方法。2.对沥青胶浆粘度预测模型进行研究改进，发现沥青胶浆的粘度随着填料体积分数的增大逐渐增大，在初期填料含量较小的情况下呈现线性增长的趋势，相对粘度增长速度较缓慢。当填料含量超过临界体积分数后，胶浆的相对粘度呈现非线性急剧增大的趋势。此时，填料体积分数的微小变化会引起胶浆粘度的急剧增长。并最终使胶浆流动停止，相对粘度趋近于无穷大。对比Einstein方程和Frankel方程的预测结果发现，在填料含量较少时Einstein方程的预测结果能够与试验测试结果吻合较好，而Frankel方程在低含量下的预测结果明显低于Einstein方程的预测结果。说明在低体积分数含量的胶浆粘度预测方面，Einstein方程具有更好的准确性。明确了胶浆粘度预测的方法和不同预测模型的适用性，有利于提高沥青胶浆粘度预测的准确性。3.根据随机填充生成原理，对现有的随机颗粒填充算法进行加窗改进处理，有效的节省了数值样本构建所耗费的计算时间。对比本文的改进方法和现有方法的计算耗时发现，改进方法在较低的面积含量时所消耗的时间与原有方法差别很小，当颗粒面积含量超过40%后，改进方法的计算耗时明显减小，说明加窗改进方法可以提高颗粒填充的计算效率。沥青胶浆内部的颗粒之间的配位数随着裹覆层厚度的增加而呈现阶梯性增长的趋势，配位数均随着裹覆厚度的增加而增加。平均配位数随着面积含量的增加而逐渐增大。通过对颗粒表面间距的研究表明，颗粒间的最小表面间距随着填料体积含量的不断增大，逐渐减小。同时，颗粒表面之间小间距出现的频率明显增大，表明颗粒之间开始慢慢的形成具有摩擦支撑作用的骨架结构。4.利用颗粒填充算法分析了颗粒形状、粗细程度、颗粒含量、就位方向以及材料刚度差异对沥青胶浆内部集中应力的影响规律，发现颗粒形状和粗细均会影响沥青胶浆内部的应力分布特性，椭圆形颗粒填充沥青时，胶浆内部的水平拉应力最大。表明扁平颗粒的存在将会增大胶浆内部的应力集中效应。采用低模量柔性颗粒增强沥青胶浆时同样会造成沥青胶浆应力集中效应，此时胶浆集中应力对颗粒模量的变化更敏感。沥青胶浆的极限承载力和切线模量随应变率的增加呈现对数线性增长的趋势，无机填料的加入能够提升沥青胶浆的极限承载力和切线模量，有利于增强沥青混合料的抗疲劳性能。对沥青胶浆蠕变性能的分析结果表明，棱角较多的颗粒有助于降低沥青混合料的粘性流动变形，从而保证沥青混合料良好的高温稳定性。更多还原

【Abstract】 Asphalt binder is made from fine aggregate and asphalt mortar. Bonding mortar is madefrom asphalt mortar and mineral powder. Because there is tenuous mineral powder in thebonding mortar, we can deal the bonding mortar as particle-filled composite to some degree.The irregular shape and distribution feature of tenuous mineral powder also will affect themechanical properties of asphalt mortar. It is stochastic for the macroscopic properties ofasphalt mortar due to the influence of many factors. Because of the irreversible forming way,some test indexes of mortar present a little more randomness when conducting mortarperformance testing, it is mainly due to the random distribution of internal structure. Usingmesomechanics research method can not only be used to make the reconstitution of internalstructure of asphalt mortar come true, but also exactly analyze the failure mechanism andviscoelastic strain characteristics of asphalt mortar and binder.In experiment test, conventional experimental measurements conduct only-image testanalysis of mixture and binders from the point of only-image study, there is great differencebetween the specialty of the internal structure of mixture and evaluation indicator ofmacroscale because of the randomness of internal structure of the material. Moreover, due tothe limit of analysis tool, empirical method need vast experiments, which is based onphenomenon. When using macro-index to evaluate and research the performance ofbituminous mixture,it will cost enormous manpower, financial and material resources, alsothere is a little more variability and bad reproducibility of the test result. However, themesomechanics analytical method can not only avoid many experiments, but also analysisthe internal mechanics reaction of mortar deeply from meso-scale. So the analysis ofmicrostructure of mortar is the precondition of researching the failure characteristics ofbituminous mixture. To conduct a model reconstitution of the asphalt mortar constructionwith microscomic modeling approach, build a real physical model combining theory and testresult, and then reveal the macroscopic response caused by the microstructure change of asphalt mortar, which has important theoretical significance and engineering applicationprospect.This paper combined with the National Natural Science Foundation of China(51278222)"The study of anisotropic properties of asphalt mixture based on digital imageprocessing technology ", investigating the filler particles analyzed the impact law on theperformance of asphalt mortar, mainly achieved the following results:1Taking high shear agitation method can effectively disperse the filler particles,prepared the asphalt mortar with consistent performance. Laser particle size analysis methodcan quickly and accurately analyze the filler gradation composition, provides a fast andeffective method to determine the filler particles such as mineral gradation.2The study of prediction model of the asphalt mortar viscosity found that the viscosityof asphalt mortar increases gradually with filler volume fraction increases, in the early caseof small filler content showed a linear growth trend, and the relative viscosity growedrelatively slow. When the filler content exceeds the critical volume fraction, the mortarrelative viscosity increased with a nonlinear sharply trend. At this point, small changes involume fraction of the filler may cause sharp increase in the viscosity of mortar. And finallythe mortar flow is stopped, the relative viscosity approaches infinity. Compared theprediction results of Frankel equation and Einstein equation showed that when the fillercontent is less the Einstein equation predictions agree well with the experimental test results,and Frankel equation predictions results at low levels significantly lower than the Einsteinequation predictions results. Shows that the Einstein equations has a better accuracy mortarviscosity prediction at a low volume fraction content. Identified mortar viscosity predictionmethod and the applicability of different prediction models, help to improve the asphaltmortar predictive accuracy of viscosity.3Improvement of particles peripheral windowing method saves sample building valuecomputing time. Contrast the computation time of this improved method and the discoveryof existing methods,the consumed time was little difference between the improved methodand the original method when the area content in the lower level, but when the particle sizeexceeds40%the improved method of calculating consumption significantly reduced which indicate that particles peripheral windowing method can improve the computationalefficiency. The coordination number of the particles in asphalt mortar showed the stepwisegrowth trend with the increasing of the coating thickness, The coordination numberincreased with the coating thickness increasing. And the average coordination numbergradually increased with area content increases. The study of distance between the particlesurface shows the minimum surface distance between the particles gradually decreases withthe content of filler volume increasing. Meanwhile, a small spacing between the particlesurface significantly increased the frequency of occurrence, suggesting that particles beganto slowly form a skeleton structure with supporting role of friction.4. Particle shape and thickness of the asphalt mortar will affect the internal stressdistribution characteristic, when the oval-shaped particles filled with asphalt, the internallevel tensile stress was the maximum. Indicate the presence of flat particles will increase thestress concentration within the mortar. Low modulus flexible particle reinforced asphaltmortar is also cause stress concentration, then mortar concentrated stress on the particlemodulus more sensitive to changes. The ultimate bearing capacity and tangent modulusasphalt mortar increased with strain rate showed a log-linear growth trend, inorganic fillerscan enhance the ultimate bearing capacity and tangent modulus, and boosting asphaltmixture fatigue performance. Creep properties of the asphalt mortar analysis showed thatmore angular particles helps to reduce the viscosity flow deformation of asphalt mixture,thus ensuring asphalt good high temperature stability.更多还原