| The uniformity of asphalt mixture is the prerequisite to ensure the excellent road performance and long-term service life of asphalt pavement.The segregation phenomenon of asphalt pavement caused by natural and human factors such as production,transportation,paving and rolling is the main reason for the local structural performance weakness of asphalt pavement and accelerating the occurrence of early pavement diseases.At present,the commonly used segregation detection methods are mainly sampling inspection after the completion of asphalt pavement,and the method is time-consuming and subjective randomness is large,and the emerging nondestructive testing method has high detection cost,and it is often unable to evaluate the paving uniformity of asphalt mixture in the process of asphalt pavement construction,which leads to the problem of asphalt mixture uniformity in highway engineering construction and quality Not enough attention has been paid in quantity acceptance.With the development of modern digital technology,digital image processing technology has been widely used in highway engineering for its high efficiency,accuracy and low cost.Aiming at the segregation phenomenon of asphalt mixture in the process of paving,based on digital image processing technology and collecting the asphalt mixture by industrial camera,this paper puts forward the pretreatment and segmentation technology of adhesive aggregate suitable for paving asphalt mixture.Based on the analysis of four sides static moment of image particles,the evaluation method and evaluation of asphalt mixture uniformity with weighted grading static moment separation coefficient are proposed Through the development of asphalt mixture paving uniformity rapid evaluation system,the field evaluation of asphalt pavement paving process uniformity is realized.The main research results and conclusions are summarized as follows(1)In the laboratory,the gradation of segregation asphalt mixture is simulated,and the variation law of segregation degree and asphalt mixture structural parameters is studied through indoor Marshall test,and the segregation evaluation index is proposed based on the change of void ratio;the key gradation interval and the change of asphalt mixture porosity with different segregation degree are determined according to Bailey method,and AC is studied respectively-13.AC-20,AC-25 different gradation types,gradation type asphalt mixture has the greatest influence on the void fraction;(2)Based on the analysis of field image samples,a digital image preprocessing method for paving asphalt mixture is proposed.Aiming at the problem of excessive segmentation of adhesion particles in the image processing of paving asphalt mixture,a digital image segmentation method suitable for paving asphalt mixture based on the extended maximum transformation watershed segmentation method is proposed The accuracy of the digital image preprocessing algorithm is verified by comparing the ratio of each grade to the total area of aggregate particles and the gradation of mixture screening test in the corresponding image area.;(3)Based on the analysis of four side static moments of aggregate particle image,the grading weighted quadrilateral moment dispersion coefficient Cv relative to the ideal uniform distribution is proposed as the evaluation index of asphalt mixture uniformity,and the calculation method and program of grading weighted quadrilateral static moment dispersion coefficient CV are given.Based on the real project,the real-time digital images of AC-13,AC-20,AC-25 graded asphalt mixture are analyzed and calculated,and the uniformity evaluation results are given according to the grading weighted quadrilateral static moment dispersion coefficient Cv;based on the segregation evaluation standard of porosity change of AC-13,AC-20,AC-25 standard grading mixture and the actual measurement of asphalt surface structure depth by sand spreading method According to the evaluation standard of structure depth segregation,the evaluation standard of paving asphalt mixture uniformity is put forward based on the grading weighted quadrilateral static moment dispersion coefficient Cv;(4)The results show that with the increase of homogeneity evaluation index CV,the segregation degree of asphalt mixture increases,and the pavement performance of asphalt mixture becomes worse obviously,in which coarse aggregate segregation affects the water stability of asphalt mixture The qualitative effect is more significant;(5)The image preprocessing and uniformity evaluation of asphalt mixture are carried out by using MATLAB image toolkit,and the rapid detection system of asphalt mixture paving uniformity is developed by combining with Labview software,and the real-time measurement and evaluation of paving uniformity of the actual road section on site are carried out,which verifies the reliability and accuracy of the system;... |
PDF Full Text Request