粗集料针片状含量对沥青混合料结构影响

Effects of flat and elongated particles content in coarse aggregate on asphalt mixture structure

摘要:

为研究引起沥青混合料内部结构差异的因素，提出并测定了不同针片状颗粒含量的沥青混合料结构参数和体积指标.运用工业CT断层成像技术和图像处理技术，采用颜色标尺标注空隙结构，以及Image-Pro Plus 6.0图像处理软件提取计算沥青混合料的空隙率，并测量沥青混合料断面粗集料颗粒的形貌参数，采用面积、纵横比AR₁和AR₂、主轴偏角均值、颗粒趋向参数Δ和棱角性等参数评价沥青混合料的结构特征.结果表明：针片状颗粒的增加使得沥青混合料毛体积密度减小，空隙率增大，且通过工业CT计算得到的空隙率大于实测空隙率；大孔隙结构主要分布于试件的中下部位，试件顶端空隙较小；随着针片状颗粒的增加，颗粒纵横比期望AR₁和AR₂线性增加，横断面粗集料颗粒面积和减小，棱角性期望增大，但是对偏角均值和Δ影响不够明显.

Abstract:

To investigate the reasons of different performance of asphalt mixture, volume index and structural parameters were measured in asphalt mixtures with different flat and elongated particles content. Void ratio of asphalt mixture was calculated based on industrial CT scanning and image processing technology, and color scale was used to mark the void structure. The parameters such as area, aspect ratio-AR₁ and AR₂, mean value of spindle deflection angle, particle trend parameter-Δ and angularity were adopted to evaluate the structural characteristics of asphalt mixture. Results show that with the increase of flat and elongated particles, the volume density of asphalt mixture decreases and the porosity increases, and the void ratio calculated by industrial CT is larger than the measured. Macro-pore structure is mainly distributed in the middle and lower part of the specimens, but the voids at the top of the specimens are smaller. With the increase of the flat and elongated particles content in mixture, the aspect ratio expectation of particles-AR₁, AR₂ and angularity expectation increases, and the cross section area of coarse aggregate particle decreases, but the influences on the mean deviation of deflection angle and grain trend are not obvious.