Microstructural Characteristics of Bituminous Mix Using X-ray CT

Abstract

Study of the internal structure of bituminous paving mixes is very essential to understand its air void characteristics which ultimately relate to the strength of these mixes. Air void (AV) distribution significantly influences the structural and functional performances of bituminous mixture. The lack of proper investigation of the AV parameters and their distribution often leads to major distress related issues. The present study is an attempt to investigate the AV properties and their distribution in a profound and precise manner using an effective and quick 3D high resolution technology such as X-Ray micro computed tomography combined with the digital image processing tools. Using the 3D Images obtained from imaging technique, the internal structure of bituminous mix was visualized and then image analysis was done to determine various AV parameters such as AV content, number of AV, AV size and shape of AV of the compacted bituminous specimen. With the help of continuous spatial data of above mentioned properties obtained from volumetric images, the homogeneity of AV distribution was evaluated. Variation of AV parameters along the vertical, horizontal and radial directions were plotted and further analyzed to find the inconsistency in their distribution. Compared to vertical direction, a significant variation was observed in the horizontal direction where the inner region contained more number of AV than that in the mid and outer regions.