Research on fractal features of basalt aggregate surface topography

The main purpose of this research is to evaluate the fractal features of aggregate surface topography through capturing three-dimensional aggregate images with a three-dimensional optical dense point cloud measurement system and a newly-developed Matlab program calculating fractal dimensions of aggregate surfaces and sizes. Through analysis and comparison on fractal features of both fine and coarse basalt aggregate, it was observed that fractal dimensions of aggregates had an obvious size. Fractal dimension gradually increased along with the measurement size increasing. No fractal feature was shown when measurement size exceeds a certain limit, and the threshold value reflected the complexity of aggregate surface morphology. For basalt aggregates of 13.2 mm, the threshold value was 12.8 mm. Fractal feature was not necessarily shown with measurement size ranged from 0.8 mm to 12.8 mm. Obvious fractal features were shown when measurement size was less than 0.8 mm.