Most modern devices for measuring texture in the macro and megatexture ranges are based on the principle of “laser triangulation”. A laser beam is projected perpendicularly onto the surface to be investigated and a special camera “observes” the patch of light on the road surface. The camera is capable of determining the height of the patch. By moving the measurement system (most often, but not necessarily, parallel to the road centre line) and measuring and recording the height of the patch at fixed intervals, it is possible to obtain a two-dimensional profile of the road surface.
A significant correlation between test results from a percussion sounding apparatus and the California Bearing Ratio (CBR value) has been established for fine soils ranging from silt to fine sandy soils I (D < 0,2 mm).
In a standardized form this equipment and test method can render invaluable services:
It has been quite a few years since nuclear measurement methods made their appearance in road construction to check the density of various materials in pavement structures. Yet there has been no proper breakthrough of such measurements in Belgium to date, whereas our neighbours have used the method sucessfully for several years.