基于数字图像处理的沥青混合料主骨架评价标准

Evaluation Indexes of Asphalt Mixture Main Skeleton Based on Digital Image Processing

为了给骨架密实型沥青混合料级配设计与优化提供指导,使设计的沥青混合料具有良好的抗车辙性能,针对目前沥青混合料骨架结构判据的不足,在分析现有沥青混合料骨架结构评价指标的基础上,基于数字图像处理技术考虑粗集料接触特性对V_(mix)~VCA计算方法进行了优化。通过对4种不同级配沥青混合料中主骨架结构细观接触分布特性进行了比较,对细观定量评价指标与宏观评价指标间的相关关系进行了分析,提出了粗集料形成较优主骨架结构的细观定性和定量评价指标和标准。结果表明:考虑粗集料接触特性,优化的V_(mix)~VCA(I)计算方法所得值比目前经验计算法大15%~20%,在骨架判别时更加严格、合理,保证粗集料相互嵌挤形成最优主骨架;沥青混合料细观定量评价指标与其宏观评价指标有较好的相关关系,能够表征沥青混合料的抗车辙性能;骨架密实型沥青混合料设计过程中通过调整级配提高平均配位数的同时降低C值,能有效改善混合料的细观指标,使主骨架的质量得到明显提升,设计的沥青混合料具有良好的抗车辙性能;粗集料形成较优主骨架结构的定性和定量评价标准为V_(mix)~VCA(I)≤V_(DRC)^(VCA),n>1.6且C<20%。

In order to provide a reference for gradation design and optimization of skeleton dense structure asphalt mixture to form good rut resistance performance for designed asphalt mixture, in allusion to the shortage of current asphalt mixture skeleton structure criterion, calculation method was optimized by considering the contact characteristics of coarse aggregates through digital image processing technique based on the analysis of existing evaluation index of asphalt mixture skeleton structure. Compared with the microscopic distribution characteristics of coarse aggregate contacts in asphalt mixture with four different gradations, the correlation between microscopic quantitative evaluation indexes and macroscopic evaluation indexes was analyzed and the microscopic qualitative and quantitative evaluation indexes and criteria for the coarse aggregates were proposed to form an optimal main skeleton. The results show that values obtained by the optimal calculation method of V mix VCA （I） are about 15% -20% larger than values based on current experience method and more strict and reasonable skeleton discriminant can guarantee interlocked coarse aggregates to form an optimal main skeleton. There is a good correlation between microscopic quantitative evaluation indexes and macroscopic evaluation indexes of asphalt mixture, with microscopic quantitative evaluation indexes representing the rut resistance performance. During the design process of skeleton dense structure asphalt mixture, the average coordination number increases and the C value decreases by adjusting the gradation, with effective improvement of microscopic indexes and the quality of the main skeleton, so the designed asphalt mixture shows good rut resistance performance. The qualitative and quantitative evaluation indexes of the optimum main skeleton structure formed by coarse aggregate are.Vmix VCA （I）≤V DRC VCA,n 〉1.6 while C〈20%.