Evaluation of adhesion between bitumen and aggregate with the digital image processing method

Abstract

Abstract Although adhesion in asphalt between bitumen and aggregates is one of the essential properties, it is still evaluated visually. European Standard EN 12697-11 provides 3 test methods for the preparation of samples for evaluation - rolling-bottle method, static method and boiling water stripping method. The method used in Latvia is different from EN 12697-11, but with similarities. Bitumen coverage is evaluated visually for all options. The result is the average value of two parallel operators. This principle of evaluation is much criticized as inaccurate and subjective. Today’s technologies are evolving, and in many fields, they are more reliable than a human. This study aims to determine whether a visual assessment method can be replaced by a digital image processing method. To evaluate the accuracy of the image processing method, four different mineral materials - granite, dolomite, quartz diorite, gravel, were selected. Samples obtained during the test procedure were tested visually and using an image processing method. For image evaluation, a mini photo studio was created, where pictures were taken using a professional camera and a budget smartphone. The smartphone was used to determine if it is possible to get high-quality images and results using budget smartphones in our pockets.