【作者】 张弘；

【导师】 邱延峻；

【作者基本信息】 西南交通大学 ， 道路与铁道工程， 2023， 硕士

【摘要】 在我国,沥青中往往具有很高的蜡含量,蜡的存在对沥青的路用性能极其不利,测量和限制沥青中的结晶蜡含量是控制沥青材料质量的关键性步骤。常用的试验测试方法如吸附法、傅里叶变温红外光谱法(VT-FTIR)和差示扫描量热法(DSC)等实验手段不仅有误差较大,操作不便等缺点,更难以从理论物理的角度去揭示蜡结晶析出的本质。因此,从理论的角度精确构建一个沥青中蜡结晶析出的理论模型显得意义重大。本论文选取了SHRP的两种沥青为研究对象,从热力学角度出发,将沥青视为固液两相系统,以相平衡理论和正规溶液模型为理论基础构建了沥青胶结料的蜡析出预测模型。将蜡析出曲线(WPC)和蜡析出温度(WPT)的建模结果与试验测试结果进行对比验证,其中试验测量方法采用VT-FTIR法和粘度法,结果表明:(1)粘度法测得的WPT相较于另外两种方法偏低,本文选取的两个试样的结果分别低17.3℃和20.8℃,而变温红外光谱可以作为一种很好地测量WPT和WPC的试验方法,其测试结果与改进后的模型结果差别不大。(2)热力学参数对建模结果影响很大,通过科学考虑正构烷烃组分熔化热的分支效应以及重质组分芳香分对体系热力学性质的影响,将两种影响效应分别乘以参数0.3和0.6之后,使模型的预测结果十分精确。本论文将沥青的有效组分划分为P(正构烷烃)、N(异构烷烃)、A(芳香分)三种组分,PNA组分作为模型的输入参数,通过沥青的四组分试验和气相色谱-质谱联用(GC-MS)进行提取和分析。组分分析结果表明:(1)沥青作为原油生产的二次产品,其体系中的重质组分芳香分、沥青质等含量很高,轻质组分含量极低。试样AAM-1和试样AAC-1的正构烷烃、异构烷烃和芳香分组分含量分别为3.65%、1.35%、41.90%和5.06%、0.67%、37.1%。(2)PNA三种组分在较高碳数下都呈现出指数衰减的趋势,利用好这一规律有利于对沥青高组分进行表征。(3)沥青的组分分布是影响蜡结晶析出的内在因素,高碳数的正构烷烃组分含量越高,会导致越高的蜡析出温度以及越剧烈的蜡析出曲线走势,而重质组分芳香分的含量可能与蜡析出温度线性相关。更多还原

【Abstract】 In China,asphalt often has a high wax content,and the presence of wax is extremely detrimental to the road performance of asphalt.Measuring and limiting the crystalline wax content in asphalt is a key step in controlling the quality of asphalt materials.Common test methods,such as adsorption method,variable temperature infrared spectroscopy(VT-FTIR)and differential scanning calorimetry(DSC),have not only large errors and inconvenient operation,but also are difficult to reveal the essence of wax crystallization from the perspective of theoretical physics.Therefore,it is of great significance to accurately construct a theoretical model for wax crystallization and precipitation in asphalt from a theoretical perspective.In this paper,two kinds of asphalt of SHRP are selected as the research objects.From the thermodynamic point of view,asphalt is regarded as a solid-liquid two-phase system.Based on the phase equilibrium theory and the regular solution model,a prediction model for wax precipitation of asphalt binder is constructed.The modeling results of wax precipitation curve(WPC)and wax precipitation temperature(WPT)were compared and verified with experimental test results.The experimental measurement methods used were VT-FTIR method and viscosity method,and the results showed that:(1)The WPT measured by the viscosity method is relatively low compared to the other two methods,and the results of the two selected samples in this article are 17.3 ℃ and 20.8 ℃ lower respectively.The variable temperature infrared spectroscopy can be used as a good experimental method for measuring WPT and WPC,and its test results are not significantly different from the improved model results.(2)The thermodynamic parameters have a significant impact on the modeling results.By scientifically considering the branching effect of the melting heat of paraffinic components and the influence of heavy aromatic components on the thermodynamic properties of the system,the two effects are multiplied by parameters0.3 and 0.6 respectively,making the prediction results of the model very accurate.This paper divides the effective components of asphalt into three types: P(Paraffinic),N(Naphthenic),A(Aromatic),The PNA components were used as input parameters for the model,and were extracted and analyzed through four component experiments of asphalt and gas chromatography-mass spectrometry(GC-MS).The results of component analysis indicate that:(1)Asphalt,as a secondary product of crude oil production,has a high content of aromatic and asphaltene heavy components in its system,while the content of light components is extremely low.The contents of paraffinic,naphthenic,and aromatic components in samples AAM-1 and AAC-1 are3.65%,1.35%,41.90%,and 5.06%,0.67%,and 37.1% respectively.(2)The three components of PNA exhibit an exponential decay trend at higher carbon numbers,which is beneficial for characterizing the high components of asphalt.(3)The distribution of asphalt components is an internal factor affecting wax precipitation.The higher the content of high carbon number paraffinic components,the higher the wax precipitation temperature and the more intense the wax precipitation curve trend.The content of heavy component aromatic components may be linearly related to the wax precipitation temperature.更多还原