酸雨对沥青及沥青混合料的侵蚀破坏机理研究

发布时间：2019-06-22 20:36

【摘要】：随着化石燃料能源———煤和石油等的消耗量日益增加,酸雨已成为全球性的环境问题之一,由此引起的沥青路面病害——矿料质地软化、磨光、沥青混合料泛油、松散及坑槽等破坏日渐严重,导致沥青路面耐久性降低。然而对于酸雨引起沥青路面破坏机理研究,无论是国内还是国外都是极为有限的。基于现有的研究水平,通过构建化学热力学、动力学参数模型,深入探讨酸雨侵蚀乳化沥青机理和破坏速率的问题；运用微观、宏观手段,利用化学反应推导方法,分析矿质材料在酸雨溶液干-湿循环作用下性能衰变的规律及破坏机理；提出简单有效的酸雨侵蚀破坏沥青混合料性能衰变的评价方法与技术指标；结合沥青、矿质材料破坏研究,经过短、中、长期酸雨溶液干湿循环,分析沥青混合料侵蚀破坏发展过程,提出破坏模型。通过该项目研究,对于预防和控制此类破坏的发生、开发防治酸雨侵蚀破坏的沥青路面新材料提供重要的理论指导。(1)通过干湿循环浸泡试验模拟酸雨对沥青的腐蚀作用,研究了不同PH值酸雨和不同腐蚀周期对沥青技术性能和微观结构的影响。试验结果表明：经过酸雨干湿循环浸泡后,沥青的针入度增大,粘度和软化点和延度下降,使得沥青的高温稳定性和低温抗裂性变差。在酸雨浸泡过程中,沥青与硫酸发生了酯化反应和烷基化反应生成了链更长的异构烷烃,使得沥青中的饱和分含量增加。沥青中的羧酸类和酚类等酸性物质在酸雨中发生了一定的溶解和电离,导致沥青中的胶质含量下降。沥青中的硫醚类、硫醇类化合物在酸雨的作用下发生了氧化缩合反应,生成了亚砜类化合物和二硫化物,沥青质的含量增加。(2)通过室内试验模拟酸雨对石灰岩、玄武岩、花岗岩三种集料的腐蚀,发现三种集料均出现了质量损失,压碎值和磨耗值上升,与沥青的粘附性下降。通过扫描电子显微镜(SEM)试验以及X射线衍射试验揭示了酸雨对集料的腐蚀机理：酸雨中的酸性物质硫酸和硝酸等与矿料中的碳酸钙、碱性氧化物等发生反应,生成溶解性较好的硫酸盐和硝酸盐等物质,反应会使矿质集料的成份流失,质量下降,空隙率增大,物理力学性质下降。(3)对经酸雨浸泡后的三种沥青混合料的回收沥青进行组分分析、红外光谱分析和热重分析,发现酸雨会破坏沥青的组分,改变沥青中四组分的相对含量,酸性物质会与集料中的成分发生反应,生成羧酸类物质,这些酸类可以与集料中的低价氧化物反应生成乳化剂,沥青膜被水剥离,导致沥青混合料发生严重的侵蚀破坏。
[Abstract]:With the increasing consumption of fossil fuel energy, coal and oil, acid rain has become one of the global environmental problems, resulting in asphalt pavement diseases-material texture softened, polished, asphalt mixture flooding, loose and pothole damage is becoming more and more serious, resulting in reduced durability of asphalt pavement. However, the research on the failure mechanism of asphalt pavement caused by acid rain is very limited both at home and abroad. Based on the existing research level, the mechanism and failure rate of acid rain erosion emulsified asphalt are deeply discussed by constructing chemical thermodynamics and kinetic parameter model, and the performance decay law and failure mechanism of mineral materials under the action of dry and wet cycle of acid rain solution are analyzed by means of microcosmic and macroscopical means and chemical reaction derivation method. A simple and effective evaluation method and technical index for the performance decay of asphalt mixture damaged by acid rain erosion are put forward. Combined with the study of asphalt and mineral material destruction, through the dry and wet cycle of short, medium and long term acid rain solution, the development process of asphalt mixture erosion and failure is analyzed, and the failure model is put forward. Through the research of this project, it provides important theoretical guidance for preventing and controlling the occurrence of this kind of damage and developing new materials for preventing and controlling acid rain erosion damage. (1) the corrosion effect of acid rain on asphalt is simulated by dry and wet cycle immersion test, and the effects of different PH value acid rain and different corrosion cycle on the technical performance and microstructure of asphalt are studied. The experimental results show that after soaking in acid rain dry and wet cycle, the penetration of asphalt increases, and the viscosity, soften point and ductility decrease, which makes the high temperature stability and low temperature crack resistance of asphalt worse. In the process of acid rain immersion, the esterification and alkylation of asphalt with sulfuric acid resulted in the formation of isomer alkane with longer chain, which increased the content of saturated components in asphalt. Acid substances such as carboxylic acids and phenols in asphalt dissolve and ionize in acid rain to a certain extent, which leads to the decrease of colloid content in asphalt. Thioether and mercaptan compounds in asphalt were oxidized and condensed under the action of acid rain to form sulfoxide compounds and disulfide, and the content of asphaltene increased. (2) the corrosion of limestone, basalt and granite aggregates by acid rain was simulated by laboratory test, and it was found that the mass loss, crushing value and wear value of the three aggregates increased, and the adhesion to asphalt decreased. The corrosion mechanism of acid rain to aggregate was revealed by scanning electron microscope (SEM) and X-ray diffraction (XRD). The acid substance sulfuric acid and nitric acid in acid rain reacted with calcium carbonate and alkaline oxide in mineral material to form sulfate and nitrate with good solubility. The reaction would make the composition of mineral aggregate lose, the mass decrease and the void ratio increase. The physical and mechanical properties decreased. (3) the composition analysis, infrared spectrum analysis and thermogravimetric analysis of the recovered asphalt of three kinds of asphalt mixtures immersed in acid rain showed that acid rain would destroy the components of asphalt, change the relative content of four components in asphalt, and the acid substances would react with the components in the aggregate to form carboxylic acids, which could react with the low price oxides in the aggregate to form emulsifiers. The asphalt film is peeled off by water, which leads to serious erosion and damage of asphalt mixture.
【学位授予单位】：长沙理工大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U414

【相似文献】