The Belgian Road Research Centre has a curviameter to measure structural road characteristics rapidly and accurately. This device measures the deformation of a road surface at one hundred points, at a survey speed of 18 km/h and with an accuracy of 0.02 mm. The rear wheel axle is loaded to weigh between 8 and 13 t. Every 5 m a sensor laid down on the road surface by a moving chain measures the temporary deflection of the pavement when the rear axle is passing over.
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.
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: