5. Mixtures treated with hydraulic and pozzolanic binders

Whatever their qualities, untreated gravel has the disadvantage of having a low E modulus, which depends on that of the subgrade. They distribute loads on the subgrade rather poorly, and are only suitable for low-traffic pavements or for certain specific uses. Engineers have therefore sought treatment techniques to stiffen them.

The first developments involved the use of cement.

The use of different binders with hydraulic or pozzolanic characteristics was then experimented with, and later generalized, as defined below.