Research On Evaluation Method Of Mixing Uniformity Of Pva Fiber Cement Stabilized Macadam

Semi-rigid base material has the characteristics of high strength,high rigidity,good water stability,good freezing stability and low cost in highway construction,so it is widely used.But its crack problem has become the main flaw of the structure,not only affects the beauty of the road,but also seriously affected the performance of the road.Adding Polyvinyl alcohol fiber into cement stabilized macadam base material can improve its deformation ability and crack resistance.Since PVA fiber in cement stabilized macadam base material plays an important role in the improvement of crack resistance,so it is necessary to study the uniformity evaluation method of PVA fiber cement stabilized macadam.There is no strict uniformity evaluation method for PVA fiber cement stabilized macadam.Based on the study of the mixing equipment and mixing mechanism,the PVA fiber cement stabilized macadam aggregate uniformity analysis specimens were prepared by dyeing,curing,coring etc.At the same time,the PVA fiber cement stabilized macadam fiber uniformity analysis specimens were prepared by chemical treatment in this paper.And the image acquisition device is designed.Combined with MATLAB digital image processing technology,this paper uses image filtering,histogram equalization,corrosion and expansion methods to preprocess the collected images.After that,the PVA fibers of different states were extracted with AOI(area of interest)in Image-Pro Plus.At the same time,the edges and centroids of coarse aggregates and fibers in the pretreatment picture were extracted by seed filling method.On the basis of this,the paper puts forward the method of evaluating the uniformity of aggregate in the fiber cement stabilized macadam and its method of calculation by using the standard deviation of four sides’ distance theory.At the same time,the paper puts forward the method of evaluating the uniformity of fiber in the fiber cement stabilized macadam and its method of calculation by using the weighted standard deviation of four sides’ distance theory.Then the software architecture and GUI interface of the uniformity detection system are designed by using MATLAB software.The software of aggregates uniformity detection system and the software of PVA fiber uniformity detection system are developed.Finally,by using the single variable method and choosing stirring time to study PVA fiber cement stabilized macadam.The effect of PVA fiber on crack resistance of cement stabilized macadam and the uniformity coefficient of standard deviation of aggregate’s four-sides distance and the uniformity coefficient of weighted standard deviation of fiber’s four-sides distance varies with the stirring time were analyzed.Then the evaluation standard of aggregate uniformity and PVA fiber uniformity evaluation standard were given.The feasibility of the uniformity evaluation method of aggregates and PVA fiber is verified.The test results show that the change tendency of the uniformity coefficient of standard deviation of aggregate’s four-sides distance and the uniformity coefficient of weighted standard deviation of fiber’s four-sides distance with stirring time are consistent with the theory.The uniformity evaluation method can effectively detect the uniformity of aggregate and fiber in PVA fiber cement stabilized,providing some reference for supervision companies,construction companies and quality inspection companies.