Measuring Bitumen Coverage of Stones using a Turntable and Specular Reflections
Hanna Källén, Anders Heyden, Per Lindh · 2013
The durability of a road is among other factors dependent on the affinity between stones in the top layer and bitumen that holds the stones together. Poor adherence will cause stones to detach from the surface of the road more easily. The rolling bottle method is the standard way to determine the affinity between stones and bitumen. In this test a number of stones covered in bitumen are put in a rolling bottle filled with water. After rolling a number of hours the bitumen coverage are estimated by visually investigating the stones. This paper describes a method for automatic estimation of the degree of bitumen coverage using image analysis instead of manual inspection. The proposed method is based on the observation that bitumen reflects light much better than raw stones. In this paper we propose a method based on the reflections to estimate the degree of bitumen coverage. The stones are put on a turntable which is illuminated and a camera is placed straight above the stones. Turning the table will illuminate different sides of the stones and cause reflections on different part of the images. The results are compared to manual inspection and are well in agreement with these. (Less)