Three Dimensional Modeling And Analysis Of Air Void Structure In Asphalt Mixture

In recent years,asphalt mixture is widely used in pavement construction and maintenance.The microstructure of the mixture is significant for pavement performance evaluation.Especially,the shape as well as spatial distribution of air voids in the mixture has a very important influence on the rutting resistance and permeability,which is worth investigation.To characterize the air voids in mixture,3D solid models of air voids were developed based on the X-ray CT images of the asphalt mixture with computer graphics and image processing technology.After that,the model of air void structure was assembled and used to analyze the shape and spatial distribution of the air voids in mixture.Based on that,the effect of the air void structure on mechanical behavior of the mixture can be studied in future.Meanwhile,a 3D microstructure model of the mixture can also be devoloped.Specifically,the work of this dissertation contains four main steps,as follows:1)Based on the computer image processing technology,an automated detection algorithm of the air void contour and a contour fitting algorithm in X-ray CT images of the mixture were developed.2)Based on the contour detection results in each layer,a mapping algorithm between a single air void and its contours in layers was developed.3)The 3D solid model of a single air void was reconstructed.Furthermore,the 3D solid model of the air void structure in the mixture was obtained based on the computer graphics techniques.4)Based on the 3D solid model of the air void structure,the shape and spatial distribution of the air voids in the mixture were obtained and analyzed.Compared with traditional methods,it can be inferred that the detection of air void information in this paper not only achieve higher accuracy but also acquire reliable results for statistical indices such as porosity,equivalent diameter and surface area.Besides,the 3D reconstruction model with intact boundary information not only well shows the true morphology and spatial distribution of air void,but also supports the microstructual simulation in future work.