基于CT技术的沥青混合料均匀性及最佳沥青用量研究
发布时间：2018-07-16 10:38
【摘要】：沥青混合料是十分复杂的非均质复合材料。长期以来,沥青混合料传统设计体系对其宏观性能的研究主要依赖于现象经验法,但是其在研究过程中需要大量耗时、耗资的室内试验,而且得出的结果差异性大,再现性差,已无法满足现代工程建设中高质量的要求。沥青混合料的宏观性能与组分相材料性能和内部结构特征等密不可分,因此基于数字图像处理技术,从细观角度研究沥青混合料宏观性能是十分必要的。首先,本文明确了沥青混合料CT图像的处理过程,提出了确定数字图像中粗集料和空隙的阂值的同心9环状分区方法。结表表明,采用同心9环状分区方法提高了数字图像中的粗集料和空隙的识别精度,特别是消除了图像边缘处粗集料的区域缺失,同时减少了粗集料内部的“麻孔”现象。再则,本文针对两种成型方法、多种压实功和三种级配类型的沥青混合料试件,基于CT技术,采用沿着试件高度方向三段式(顶段、中部和底端)的分区方法对沥青混合料内部结构的计算空隙率及其影响因素进行了分析。以中部空隙率的三个特征指标建立了混合料试件整体计算空隙率的“预测模型”,并检验了“预测模型”的计算精度。根据“预测模型”和三维重构模型分别计算得到的空隙率,分析了其与实测空隙率之间的差异。结果表明,级配类型对整体计算空隙率的有效性影响较大,成型方法和压实功对整体计算空隙率的有效性影响较小；“预测模型”计算的结果精度较高,达到了整体计算空隙率的98.98%；与混合料实测空隙率相比,应用“预测模型”计算AC和SMA混合料的空隙率精度较OGFC混合料的高；应用“预测模型”计算得到的空隙率与根据三维重构模型计算得到的差异较小。其次,为了有效的测试和评价沥青混合料内部结构均匀性,考虑粗集料、沥青砂浆和空隙各组分的作用,提出了一种以各组分密度为特征值的沥青混合料内部结构均匀性识别方法(HIMDI),采用不同沥青用量条件下三种不同级配类型的沥青混合料试件,对其内部结构均匀性进行了定量检验。同时,研究了沥青用量、压实功、级配类型对混合料试件内部结构均匀性的影响,以及讨论了HIMDI的实际应用。结果表明,基于本方法提出的均匀性评价参数可以识别单一或一组沥青混合料试件的内部结构均匀性,并且通过分析计算得到三种不同级配类型沥青混合料的最佳沥青用量与室内试验获得的相差分别为0.07%、0.1%和0.55%；沥青用量和级配类型对沥青混合料内部结构均匀性具有显著影响,而压实功对沥青混合料内部结构均匀性影响规律不同；采用均匀性评价参数识别了沥青混合料试件的沥青用量、均匀性的相对薄弱位置以及相同成型因素条件下试件制作的平行性。此外,基于本文提出的沥青混合料空隙率预测模型以及均匀性评价方法,根据沥青混合料马歇尔设计方法中体积参数与内部结构组分特征值的关系,并考虑沥青混合料内部结构均匀性,建立了AC和SMA混合料的最佳沥青用量确定方法。结果表明,利用CT技术确定的混合料内部结构组分特征参数可以准确的表征AC和SMA混合料的马歇尔体积设计方法中的空隙率、间隙率和饱和度等体积参数；对于AC和SMA混合料,采用本文给出的沥青混合料设计方法与根据现行马歇尔设计方法分析得到的沥青混合料最佳沥青用量相差分别为0.01%和0.179%。
[Abstract]:Asphalt mixture is a very complex heterogeneous composite material. For a long time, the research on the macro performance of asphalt mixture based on the traditional design system mainly depends on the phenomenal experience method. However, it needs a lot of time-consuming, expensive indoor test in the study process, and the result is big difference and poor reproducibility, so it can not satisfy the modern workers. The macro performance of asphalt mixture is closely related to the properties of phase separation material and internal structure. Therefore, it is necessary to study the macro performance of asphalt mixture from the micro angle based on the digital image processing technology. First, the process of the CT image processing of the asphalt mixture is confirmed. The concentric 9 ring partition method is used to determine the gap between the coarse aggregate and the gap in the digital image. It is shown that the concentric 9 ring partition method improves the recognition accuracy of the coarse aggregate and the gap in the digital image, especially the deletion of the coarse aggregate at the edge of the image, and the reduction of the "jute hole" inside the coarse aggregate. According to two kinds of molding methods, various compaction work and three gradation types of asphalt mixture test parts, based on CT technology, the calculation of the internal structure of asphalt mixture by the method of zoning along the height direction of the specimen (top, middle and bottom) is used to analyze the calculated void ratio and the influencing factors of the internal structure of the asphalt mixture, with the three characteristics of the middle void ratio in the middle. The "prediction model" for the overall calculation of void fraction is established and the calculation accuracy of the "prediction model" is tested. According to the void ratio calculated by the prediction model and the three-dimensional reconstruction model, the difference between the calculated void ratio and the measured void ratio is analyzed. The results show that the gradation type is effective for the overall calculation of the void ratio. The effect of the molding method and the compaction work on the effectiveness of the overall calculated void ratio is smaller. The prediction model has a high accuracy and reached 98.98% of the total calculated void ratio. Compared with the measured void ratio of the mixture, the accuracy of the void ratio of the AC and SMA mixtures is calculated by using the "prediction model" than the OGFC mixture. In order to effectively test and evaluate the internal structure uniformity of the asphalt mixture, a kind of asphalt mixture with the characteristic values of each component density is proposed in order to effectively test and evaluate the internal structure uniformity of the asphalt mixture and consider the effects of the coarse aggregate, the asphalt mortar and the voidage components. The internal structure uniformity identification method (HIMDI) is used to test the internal structure uniformity of three different gradation types under different asphalt content conditions. Meanwhile, the effect of asphalt content, compaction work and gradation type on the internal structure uniformity of the mixture is studied, and the HIMDI is discussed. The results show that the uniformity evaluation parameters based on this method can identify the internal structure uniformity of a single or a group of asphalt mixture specimens, and the difference between the best asphalt content of the three different gradation types of asphalt mixture and the indoor test is 0.07%, 0.1% and 0.55% respectively. The green amount and gradation type have significant influence on the internal structure uniformity of asphalt mixture, and the influence of compaction work on the internal structure uniformity of asphalt mixture is different. Using the uniformity evaluation parameter to identify the asphalt content of asphalt mixture, the relative weak position of uniformity and the system under the same forming factors. In addition, based on the prediction model of void fraction of asphalt mixture and the method of uniformity evaluation proposed in this paper, according to the relationship between the volume parameters of the asphalt mixture Marshall design method and the characteristic value of the internal structure, and considering the internal structure uniformity of the asphalt mixture, the optimum asphalt content of the mixture of AC and SMA is established. The results show that the characteristic parameters of the internal structure of the mixture determined by CT technology can accurately characterize the volume parameters such as void ratio, clearance rate and saturation in the Marshall volume design method of AC and SMA mixture. For AC and SMA mixtures, the design method of asphalt mixture presented in this paper and the present method are based on the present method. The difference of the best asphalt content obtained by Marshall design method is 0.01% and 0.179%. respectively.
【学位授予单位】：大连海事大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：U414
本文编号：2126121
[Abstract]:Asphalt mixture is a very complex heterogeneous composite material. For a long time, the research on the macro performance of asphalt mixture based on the traditional design system mainly depends on the phenomenal experience method. However, it needs a lot of time-consuming, expensive indoor test in the study process, and the result is big difference and poor reproducibility, so it can not satisfy the modern workers. The macro performance of asphalt mixture is closely related to the properties of phase separation material and internal structure. Therefore, it is necessary to study the macro performance of asphalt mixture from the micro angle based on the digital image processing technology. First, the process of the CT image processing of the asphalt mixture is confirmed. The concentric 9 ring partition method is used to determine the gap between the coarse aggregate and the gap in the digital image. It is shown that the concentric 9 ring partition method improves the recognition accuracy of the coarse aggregate and the gap in the digital image, especially the deletion of the coarse aggregate at the edge of the image, and the reduction of the "jute hole" inside the coarse aggregate. According to two kinds of molding methods, various compaction work and three gradation types of asphalt mixture test parts, based on CT technology, the calculation of the internal structure of asphalt mixture by the method of zoning along the height direction of the specimen (top, middle and bottom) is used to analyze the calculated void ratio and the influencing factors of the internal structure of the asphalt mixture, with the three characteristics of the middle void ratio in the middle. The "prediction model" for the overall calculation of void fraction is established and the calculation accuracy of the "prediction model" is tested. According to the void ratio calculated by the prediction model and the three-dimensional reconstruction model, the difference between the calculated void ratio and the measured void ratio is analyzed. The results show that the gradation type is effective for the overall calculation of the void ratio. The effect of the molding method and the compaction work on the effectiveness of the overall calculated void ratio is smaller. The prediction model has a high accuracy and reached 98.98% of the total calculated void ratio. Compared with the measured void ratio of the mixture, the accuracy of the void ratio of the AC and SMA mixtures is calculated by using the "prediction model" than the OGFC mixture. In order to effectively test and evaluate the internal structure uniformity of the asphalt mixture, a kind of asphalt mixture with the characteristic values of each component density is proposed in order to effectively test and evaluate the internal structure uniformity of the asphalt mixture and consider the effects of the coarse aggregate, the asphalt mortar and the voidage components. The internal structure uniformity identification method (HIMDI) is used to test the internal structure uniformity of three different gradation types under different asphalt content conditions. Meanwhile, the effect of asphalt content, compaction work and gradation type on the internal structure uniformity of the mixture is studied, and the HIMDI is discussed. The results show that the uniformity evaluation parameters based on this method can identify the internal structure uniformity of a single or a group of asphalt mixture specimens, and the difference between the best asphalt content of the three different gradation types of asphalt mixture and the indoor test is 0.07%, 0.1% and 0.55% respectively. The green amount and gradation type have significant influence on the internal structure uniformity of asphalt mixture, and the influence of compaction work on the internal structure uniformity of asphalt mixture is different. Using the uniformity evaluation parameter to identify the asphalt content of asphalt mixture, the relative weak position of uniformity and the system under the same forming factors. In addition, based on the prediction model of void fraction of asphalt mixture and the method of uniformity evaluation proposed in this paper, according to the relationship between the volume parameters of the asphalt mixture Marshall design method and the characteristic value of the internal structure, and considering the internal structure uniformity of the asphalt mixture, the optimum asphalt content of the mixture of AC and SMA is established. The results show that the characteristic parameters of the internal structure of the mixture determined by CT technology can accurately characterize the volume parameters such as void ratio, clearance rate and saturation in the Marshall volume design method of AC and SMA mixture. For AC and SMA mixtures, the design method of asphalt mixture presented in this paper and the present method are based on the present method. The difference of the best asphalt content obtained by Marshall design method is 0.01% and 0.179%. respectively.
【学位授予单位】：大连海事大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：U414
【引证文献】
相关会议论文 前1条
1 张倩;白燕;王天利;;沥青混合料试件孔隙率微观测定方法研究[A];第17届全国结构工程学术会议论文集（第Ⅱ册）[C];2008年
，本文编号：2126121
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