乳化沥青冷再生混合料的细观结构研究

发布时间：2018-06-07 19:32

本文选题：乳化沥青冷再生混合料 + 细观结构　；参考：《东南大学》2015年硕士论文

【摘要】：室内试验结果和工程应用情况表明,乳化沥青冷再生混合料的力学性能与热拌沥青混合料存在较大的差异。由于沥青混合料的细观结构对其力学性能有较大的影响,因此,为了深入研究乳化沥青冷再生混合料的力学机理,首先需要对其细观结构进行全面的分析。本文利用数字图像处理技术和X-ray CT无损伤扫描技术对乳化沥青冷再生混合料的细观结构展开研究。首先,利用工业CT获取了乳化沥青冷再生混合料试件的CT扫描图像,在对CT扫描图像进行一系列的图像处理之后,采用改进的OTSU法计算灰度阈值,解决了CT扫描图像的亮度不均匀问题,最终成功地提取出了乳化沥青冷再生混合料中空隙、水泥乳化沥青砂浆和粗集料颗粒三种材质的图像。其次,分析了乳化沥青冷再生混合料的空隙空间分布特性,并提出“空隙级配”的概念对其空隙统计特性进行研究。研究表明,随着集料级配由细变粗,乳化沥青冷再生混合料的空隙尺寸逐渐变大,空隙数量逐渐减少：空隙级配能够较好地反映出乳化沥青冷再生混合料的空隙统计特性,Weibull分布模型对其有较好的拟合效果；与热拌沥青混合料相比,乳化沥青冷再生混合料的空隙数量较多,空隙级配较细。然后,设计了沥青砂浆厚度的采样方法,提出了“厚度谱”的概念,研究了水泥乳化沥青砂浆在乳化沥青冷再生混合料中的分布状况。研究表明,厚度谱能够较好地反映沥青砂浆的厚度组成状况,对数正态分布模型对其有较好的拟合效果；与热拌沥青混合料相比,乳化沥青冷再生混合料中水泥乳化沥青砂浆厚度谱的期望、众数和最大比重都比较小。最后,针对乳化沥青冷再生混合料中的粗集料颗粒展开了一系列研究。研究表明,乳化沥青冷再生混合料的均匀性随着级配由细变粗而逐渐降低；与马歇尔击实和静压相比,旋转压实能够使得乳化沥青冷再生混合料分布更为均匀,并且粗集料颗粒的主轴方向角较小：与新集料颗粒相比,旧料颗粒的扁平比FER和表面纹理指数STI较小,棱角性指数AI较大。
[Abstract]:The results of laboratory test and engineering application show that the mechanical properties of cold recycled emulsified asphalt mixture are different from that of hot mix asphalt mixture. Because the meso-structure of asphalt mixture has great influence on its mechanical properties, in order to study the mechanical mechanism of emulsified asphalt cold recycled mixture, it is necessary to make a comprehensive analysis of its meso-structure. In this paper, the mesoscopic structure of cold recycled asphalt mixture is studied by digital image processing and X-ray CT scanning without damage. Firstly, the CT scanning images of cold recycled asphalt mixture samples were obtained by industrial CT. After a series of images were processed, the gray threshold was calculated by using the improved Otsu method. The problem of uneven brightness of CT scanning image is solved, and finally three kinds of images of cold recycled mixture of emulsified asphalt, cement emulsified asphalt mortar and coarse aggregate particle are extracted successfully. Secondly, the characteristics of void space distribution of emulsified bitumen cold recycled mixture are analyzed, and the concept of "void gradation" is put forward to study the statistical characteristics of the void. The results show that as aggregate gradation changes from fine to coarse, the void size of cold recycled asphalt mixture increases gradually. The number of voids decreases gradually: the void gradation can better reflect the statistical characteristics of the void in cold recycled asphalt mixture and the Weibull distribution model has a better fitting effect compared with the hot mix asphalt mixture. Emulsified bitumen cold-recycled mixture has a large number of voids and fine gradation. Then, the sampling method of asphalt mortar thickness is designed, the concept of "thickness spectrum" is put forward, and the distribution of cement emulsified asphalt mortar in cold recycled asphalt mixture is studied. The results show that the thickness spectrum can well reflect the thickness composition of asphalt mortar, and the logarithmic normal distribution model has a better fitting effect than that of hot mix asphalt mixture. The thickness spectrum of cement emulsified asphalt mortar in cold recycled mixture of emulsified asphalt is expected, mode and maximum specific gravity are smaller. Finally, a series of research on coarse aggregate particles in cold-recycled emulsified asphalt mixture was carried out. The results show that the uniformity of cold recycled asphalt mixture decreases with the gradation increasing from fine to coarse, and compared with Marshall compaction and static pressure, rotary compaction can make the distribution of emulsified asphalt cold recycled mixture more uniform. The main axis angle of coarse aggregate is smaller: compared with the new aggregate particle, the flat ratio of the old particle is smaller than fer and the surface texture index STI is smaller, and the angle index AI is larger than that of the new aggregate particle.
【学位授予单位】：东南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U414

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