Conclusions from the Longtime Behaviour of Cement Bound Road Bases

Cement-bound road bases of 16 heavily loaded Autobahns in West Germany (12 road bases under concrete pavements and 4 under asphalt pavements) were investigated regarding bond, damage due to frost and erosion, compressive strength, water permeability, frost and erosion resistance. The investigations showed that cement-bound road bases are proved in practice. Cement-bound road bases can have large differences in their water permeability, even within the same section. Therefore a general requirement on the permeability would be difficult. As opposed to the erosion test, the correlation between the results of the host lest iii the laboratory and the behaviour of road bases subjected to frost action in practice was not satisfactory. To gain a sufficient durability of cementbound road bases it is recommended to increase the required compressive strength, which will result in a higher cement content. This is possible because in Germany cement-bound bases are notched to avoid reflective cracking in the pavement.