Analysis of approaches to quantitative assess-ment of bitumen binders adhesion to stone mate-rials using digital image processing methods

Abstract. Problem. At present, in Ukraine, when designing the composition of asphalt mixtures of various types, it is mandatory to determine the adhesion of the adopted bituminous binders to the surface of stone materials by using the methods presented in DSTU EN 12697-11 and DSTU 8787. These methods are based on determining the resistance to the peeling action of water and have a common disadvantage in the form of visual assessment of the surface area of stone materials covered with bituminous binder after the test. The subjectivity of evaluating the results obtained significantly affects their accuracy and reproducibility. The solution to this problem is the use of digital image processing methods for evaluating the results of bitumen adhesion to stone materials. Goal. The aim of the work was to analyse the existing methods of quantitative evaluation of binders' adhesion to stone materials using digital image processing methods. Methodology. To achieve this goal, the analysis of foreign literary sources devoted to the issue of bitumen binders cohesion estimation was carried out. Results. On the basis of the literature analysis, the basic conditions for obtaining a high-quality image of a bituminous material tested by one of the standard methods of adhesion determination were established. The currently existing methods of digital image processing (threshold grey method, entropy-based segmentation method and colour space analysis method) are analysed. Originality. It has been established that the most suitable conditions for obtaining a high-quality image of a sample are the use of an intense directional light source, ensuring that the influence of natural scattered light and glare on the bitumen surface is avoided. The most common method of image processing is the grey threshold method. Despite the fact that there are certain limitations of this method, it is advisable to use it for laboratory evaluation of the results of determining the adhesion of bitumen to stone materials. Practical value. The analysis carried out can be used in the development of a domestic method of digital image processing of stone materials after the adhesion test.