Research On Gradation Detection Techniques Of Asphalt Mixture Based On Digital Image

The asphalt pavement is main pattern of the highway in our country. The gradation of asphalt mixture is the primary factor that affects the operational performance of the asphalt pavement, and thus is the important test content in the quality process control of asphalt pavement construction. The traditional test method is operation-complex, time-consuming, and the test result is object to the human errors. Therefore, the realization of fast and intelligent test for the gradation of the asphalt mixture has the important practical significance.This paper applies the digital image processing technology in the gradation automaticdetection of the asphalt mixture and makes thorough research to the asphalt mixture digitalimage transformation, enhancement, restoration, segmentation, as well as the asphalt mixture digital image characteristic description and analysis and the application of mathematical morphology in the binary image of asphalt mixture.This paper has designed the hardware equipment to obtain asphalt mixture digital image, and on the basis of some image processing by using Matlab7.0, it carries on the programming realization to the gradation automatic detection system of the asphalt mixture.In the paper, it extracts such characteristic as the area, mean gray value, standard deviation, min and max gray value, centroid, perimeter, minimum enclosing rectangle, fitting ellipse (major axis length, minor axis length, angle), circularity of the asphalt mixture aggregate particle region, then according to the aggregate particle area, restored ball volume and restored ellipse spheroid volume, it separately calculates the passing rate of the aggregate particles of the asphalt mixture in each grad, and draws up the grading curve of the asphalt mixture automatically.Considering that the proportion of fine aggregate particles is a little smaller than the design value while the proportion of coarse aggregate particles is slightly bigger than the design value, the paper carries on the analysis of detected gradation of fine aggregate and coarse aggregate separately with the design value, and obtains that the detected gradation of fine aggregate is smaller than the design value to compare, but the difference between the detected gradation of coarse aggregate and the design value is not big. Further more, it carries on the analysis and the description to the error resource and error compensate methods.