基于计算机图像处理技术的断级配沥青混合料三维空隙率计算

Calculation of Three Dimensional Air Void Fraction of Gap Graded Asphalt Mixture Based on Computer Image Processing Technology

为了揭示断级配SAC-16沥青混合料中的空隙分布形态,采用CT设备对标准马歇尔击实与静压两种方法成型的SAC-16沥青混合料试件进行断层扫描。应用计算机图像处理系统Mimics对SAC-16的空隙CT值进行分析,确定其阈值上限为578HU,采用该阈值上限对空隙进行分离及三维重构,利用三维重构图像对空隙率进行计算,并将三维计算空隙率与表干法实测空隙率进行比较分析。结果表明,SAC-16试件边缘存在相互连通的大空隙,试件内部多为不连通且分布均匀的小空隙,马歇尔击实与静压成型试件的空隙率分别为4.5%和7.3%,三维图像计算值较表干法实测值更接近于真实空隙率,为断级配沥青混合料空隙率计算提供了有益参考。

In order to reveal the distribution of voids in gap graded asphalt mixture SAC-16,CT equipment is adopted to scan SAC-16 specimens compacted by Marshall and static methods,and the tomography images are then achieved.The Mimics Image Control System is employed to analyze CT threshold of air voids,the obtained upper threshold is 578HU,and the air voids separation and three-dimensional reconstruction are conducted by using this upper threshold.The three-dimensional reconstruction image was used to calculate the void fraction,and the three-dimensional calculated void fraction was compared with the surface dry method.The results show that there are large interconnected voids at the edge of SAC-16 specimen,and most of them are unconnected and evenly distributed small voids.The voids of Marshall compaction and static pressing are 4.5%and 7.3%respectively.The calculated value of 3D image is closer to the real void ratio than the measured value by surface dry method,which provides a useful reference for void fraction calculation of gap-graded asphalt mixture.