粗集料形态特征及其对沥青混合料高温抗剪强度的影响

采用60℃单轴贯入试验, 确定沥青混合料高温抗剪强度。使用数字图像处理技术, 从形状、棱角性和表面纹理对粗集料二维形态特征进行具体描述, 运用等效椭圆法和筛孔尺寸修正系数识别粗集料级配。结合MATLAB软件编写程序提取粗集料形态参数, 确定与沥青混合料高温抗剪强度相关的粗集料二维形态特征指标, 利用图像拓扑性质欧拉数定量评价粗集料骨架稳定性。研究结果表明: 随着粗集料的长宽比和偏心率的降低, 等效椭圆周长比和纹理指数的提高, 沥青混合料高温抗剪强度增加; 随着欧拉数的减小, 骨架密实型沥青混合料中粗集料骨架结构的稳定性增大, 高温抗剪强度增强。

Morphological character of coarse aggregate and its influence on high-temperature shear strength of asphalt mixture

The high-temperature shear strength of asphalt mixture was confirmed by using uniaxial penetration test at 60 ℃. The 2D morphological characters of coarse aggregate were described in terms of shape, angularity and surface texture by using digital image processing technology. The gradation of coarse aggregate was identified based on equivalent ellipse method and sieve size correction factor. The morphological characters of coarse aggregate were extracted by MATLAB, and some characters affecting the high-temperature shear strength of asphalt mixture were proved. Euler number of image in digital topology was applied to quantify the skeleton stability of coarse aggregate. Analysis result shows that the shear strength of asphalt mixture increases due to coarse aggregates with low aspect ratio and eccentricity, high angularity index of equal ellipse perimeter and surface texture parameter. As Euler number decreases, the skeleton structure of coarse aggregate in asphalt mixture with dense framework structure becomes steadier, which leads to higher high-temperature shear strength of asphalt mixture.