Research On Morphology Quantification Of Aggregates Based On 3D Solid Modeling

In recent years,asphalt mixtures have been widely used in pavement engineering.The morphology of aggregates has an important influence on the microstructure of the mixture.Therefore,it is necessary to quantify and analyze the morphology of aggregates in asphalt mixture.In this dissertation,the three-dimensional(3D)solid models of aggregates were constructed based on the X-ray CT imaging with image processing and computer graphics techniques.Based on 3D models,the aggregate volume,orientation,sieve size,sphericity,and angularity was quantified in 3D scheme.In addition,the volume and sieve size of the aggregate was validated by laboratory measurements.At last,310 coarse aggregates in an asphalt mixture were reconstructed to quantify and analyze the morphology of the aggregates.The main work can be summarized as follows:(1)With image processing and computer graphics techniques,two-dimensional(2D)aggregate outlines were detected in X-ray CT images to construct the 3D solid models of aggregates based on the mapping between the aggregate and its outlines.(2)Based on the 3D model of an aggregate,the principal axis and orientation of the aggregate was determined by the developed searching algorithm for the minimum bounding box of the aggregate.The cross section which determines the sieve size of the aggregate was identified to calculate the aggregate sieve size by the developed searching algorithm for the control surface.The mean errors of the aggregate volume and sieve size between virtual and laboratory measurement are 1.2% and 2.2%,respectively.(3)The aggregate minimum bounding box based on the minimum bounding sphere,calculate the volume equivalent radius of aggregate and the minimum bounding sphere radius ratio as a quantitative indicator of aggregate sphericity;write algorithm triangle aggregate model is discretized,the calculation method of adjacent triangles between vector angle,and to set expected minimum bounding sphere for reference,the evaluation of aggregate angularity.(4)Coarse aggregates in a mixture were reconstructed through X-ray images,based on which the volume,orientation,sieve size,sphericity and angularity of aggregates were quantified and analyzed.Data proves the validation,feasibility and efficiency of the proposed methodology.