【作者】 尹应梅；

【导师】 张肖宁；

【作者基本信息】 华南理工大学 ， 结构工程， 2011， 博士

【摘要】 随着高速公路里程的日益增加,沥青路面的早期损坏现象不断涌现。相关研究表明,沥青路面的各种损坏均与沥青混合料的粘弹性有关。沥青混合料是由非均质分布的矿料、沥青和空隙组成的复杂三相体系,其粘弹性能与各组分的力学特性及体积分数密切相关,目前沥青混合料复数剪切模量G^*和相位角计算未直接利用沥青流变数据,而沥青路面经常处于车辆动荷载作用下。因此,基于动态力学分析（DMA）方法研究沥青混合料宽频宽温动态粘弹特性和根据各组分特性研究沥青混合料动态模量预估方法是非常重要的。DMA是测试材料在周期性变化应力或应变作用下材料发生形变时模量和阻尼特性。DMA方法通常在小应变条件下测定,小应变条件符合路面变形规律;且DMA只需小试样就可以在宽频宽温条件下连续测定,在较短的时间内获得不同应力、应变、时间、温度和频率范围内沥青混合料的动态力学性能,可全面评价沥青混合料的粘弹力学行为。沥青混合料的粘弹力学行为分析的前提条件是获得粘弹函数主曲线。借鉴国内外研究成果,采用高级剪切流变仪AR-2000对沥青混合料进行DMA频率扫描;再利用时温等效原理验证沥青混合料属于简单热流变材料,仅需水平移动就可得到粘弹函数主曲线,文中采用最小二乘法非线性拟合获得的主曲线涵盖工程应用的全部频率范围,为全面研究沥青混合料粘弹行为提供充分依据。应用DMA频率谱和时温等效原理获得沥青的玻璃化转变温度（T_g）和沥青混合料的T_g,克服了DMA温度谱可能未覆盖T_g的不足。动态频率扫描（DFS）是获得材料物性特征指标T_g的有效方法。沥青的T_g与沥青混合料的T_g的变化趋势一致,且相关性良好,并与WLF方程中的C₂有良好的相关性。结果表明,沥青和沥青混合料低温性能可用同一指标T_g评价。在对比已有流变模型基础上,选用CAM模型基于主曲线研究了沥青及沥青混合料宽温宽频域内的粘弹力学行为。重点讨论不同空隙率沥青混合料极限低频和极限高频时粘弹行为,以及在低温、中温、中高温、高温时沥青混合料的粘弹比例。研究表明,CAM模型是研究沥青混合料粘弹行为的有效模型,其参数物理意义明确,且对体积指标变化较敏感,能为沥青混合料性能研究及工程应用提供指导。为了描述沥青混合料的复杂的动态粘弹力学行为,对沥青混合料的动态粘弹性能的本构关系进行了研究,分别采用广义Maxwell模型和和分数阶导数Maxwell模型、Burgers模型和分数阶导数Burgers模型对动态粘弹性能进行拟合,并对经典粘弹模型和分数阶导数模型的拟合结果进行分析。分析发现,广义Maxwell模型在曲线两端拟合效果较差,分数阶导数Maxwell模型的拟合效果较好,且拟合得到的参数具有一定的物理意义,可定量评价沥青混合料的动粘弹特性;Burgers模型不能很好的拟合动态蠕变曲线,在蠕变开始阶段偏差尤为明显,分数阶导数Burgers模型可以较精确的描述沥青混合料的动态蠕变曲线。结果表明,分数阶导数模型可较好的描述沥青混合料动粘弹行为。在分析沥青混合料粘弹函数影响因素敏感性的基础上,推导了改进的Hirsch模型;再根据Superpave的沥青流变数据和沥青混合料的体积参数,采用改进的Hirsch模型预估了沥青混合料的剪切模量和相位角。结果表明,预估值和实测值相关性良好（ R² > 0.89）,改进的Hirsch模型是一种简单可行的预估沥青混合料复数剪切模量和相位角的方法。改进的Hirsch模型G^*计算充分考虑了沥青混合料的体积组成特性和Superpave沥青的G^*值,而且参数少,这样减少了误差且易操作;大大节约了实验时间和费用;改进的Hirsch模型为沥青混合料动态剪切模量和相位角的预估及粘弹特性的研究提供了一种有效途径。更多还原

【Abstract】 With the highway mileage growing, more and more early damage in asphalt pavement has emerged. Researches indicated that various damages of asphalt pavement are relevant to viscoelastic of asphalt mixtures. Asphalt mixtures are particulate composite materials consisting of uniformly distributed mineral aggregates, asphalt binder and air voids. The viscoelastic characteristics are contact with various components. At present, the studies on viscoelastic behavior of asphalt mixtures do not make full use of Superpave asphalt rheological data. Meanwhile, asphalt pavements often bear vehicle load. Therefore, this research on viscoelastic characteristics in wide-temperature-wide-frequency for asphalt mixtures based on dynamic mechanical analysis(DMA)and predicting according to the components properties are very necessary.Dynamic mechanical analysis (DMA) is an important method to study the viscoelastic properties of asphalts and aphalt mixtures under cyclic stress or strain. DMA is usually operated under conditions of small strain and small strain deformation consistent with the pavements. DMA was employed to obtain dynamic mechanical properties of asphalts and asphalt mixtures within different stress, strain, time, temperature and frequency region using a small sample, which can not be obtained from others method. Therefore, DMA method can evaluate the viscoelastic behavior of asphalt mixtures completely. To obtain the viscoelastic function master curve is prerequisite for viscoelastic behavior analysis of asphalt mixtures. According to domestic and foreign research results, a high advanced shear rheometer AR-2000 is used to obtain the DMA sweep test data. Asphalt mixtures is a simple thermal rheological materials determined by time-temperature superposition principle, and just horizontal movement can viscoelastic function master curve for asphalt mixtures, and master curve obtained by non-linear fitting covering the entire frequency range of engineering applications provides a sufficient basis for a comprehensive study of the viscoelastic behavior of asphalt mixtures.The glass transition temperature(T_g)for asphalts and asphalt mixtures are got using the DMA frequency spectrum and time-temperature superposition principle and overcome the shortage that dynamic mechanical temperature spectra may not cover the T_g. The dynamic frequency sweep (DFS) is an effective method to obtain T_g characteristic index of asphalt and asphalt mixtures. T_g of sphalts and T_g of asphalt mixtures are the same trend and good correlation. Meanwhile, there is good correlation between WLF equation in the C2 in WLF equation and T_g of asphalt and asphalt mixtures. The results show that the same index T_g can evaluate the lower temperature performance for asphalt and asphalt mixtures.Comparison of other rheological models, a CAM model with clear physical meaning of parameters is used to study viscoelastic behavior for asphalt mixtures in wide-temperature -wide-frequency based on their master curves. The viscoelastic behavior for asphalt mixtures in limit low frequency and limit high frequency and the viscoelastic ratio for asphalt mixtures at low temperature, intermediate temperature, intermediate-high temperature and high temperature are investigated using of CAM model. The results show that CAM model with good clear physical meaning and sensitive to volume index changes is effective model of quantitative study for asphalt mixture viscoelastic behaviors, can study the performance and provide application guidance for asphalt mixtures.To analyze the dynamic complex viscoelastic properties of asphalt mixtures, dynamic viscoelastic constitutive equation of asphalt mixtures dynamic properties was studied, consisting of generalized Maxwell model and fractional derivative Maxwell model, Burgers model and fractional derivative model, and the fitting results of classical viscoelastic model and fractional derivative model are analyzed. The results indicate that generalized Maxwell model fit less effective at both end of the curve, but fractional derivative Maxwell model with clear physical meaning parameters in some degree can fit the test data well and can describe the dynamic performance for asphalt mixtures in quantitative; Burgers model can not fit the dynamic creep curve accurately and the beginning of fitting deviation in creep curve is particularly evident, while fractional derivative Burgers model can describe the asphalt mixture dynamic creep curves accurately.It is concluded that the fractional derivative model can descirbe the dynamic viscoelastic behavior accurately. Considering the components of asphalt mixtures material impact on its viscoelastic behavior, an improved Hirsch model was derived. A micromechnical improved Hirsch model is used to predicte the shear modulus and phase angle of asphalt mixtures using Superpave asphalt rheological data and considering. The results show that there is a good correction between predicted value and measured value( R~2 > 0.89)and the improved Hirsch model is a simple and practical approach to estimate the complex shear module and phase angle for asphalt mixtures. If measured the volume index of asphalt mixtures, its viscoelastic function paramaters can estimate according to asphalt rheological data at same temperature and same frequency and its components fractions. This greatly reduces the experimental cost and time. Improved Hirsch model for provides an effective way to estimate dynamic shear modulus and phase angle for asphalt mixtures and investigate the viscoelastic behavior of asphalt mixtures.更多还原