ABSTRACT
The loss of bitumen stone adhesion is a severe problem, ultimately resulting in stripping, stone loss, and pothole formation. The European standard, EN 12697-11 describes three methods to determine the affinity between aggregate and bitumen: the rolling bottle test, the static immersion test and the boiling water test. To determine the bitumen stone coverage, the EN norm allows two methods: a visual determination of the degree of binder coverage, for the static immersion and rolling bottle test, and a titration method, in case of the boiling water test. Obviously, both methods are dealing with shortcomings, the visual determination because of its subjectivity, and the titration method because of its need for reagents, like HF or HCl. In this study, a digital image analysis is proposed as a method to evaluate the bitumen coverage on the aggregate. First results and a comparison to the titration method are shown in the paper.
