### EFFECT OF CAPPING LAYERS ON THE IMPROVEMENT OF SUBGRADE ...

With help of diagram illustrated on Fig. 2 the required capping layer thickness can be determined according to the following example: a weak subgrade (with modulus of 2 = 20 MPa), has to be improved with a capping layer stabilised in situ with hydraulic binder (with modulus of 1=1200 MPa) and the required equivalent modulus at the formation level is v=80 MPa.