Determination of foundation thickness for performance design

There are a large number of possible designs for the various combinations of subgrade surface modulus and foundation material, in order to achieve the desired foundation class. 

Class 2 Sub-base with CBGM-strength C3/4 or C5/6 Class 3 Sub-base with CBGM-strength C8/10 

The determination of the foundation la) er thickness is carried out having determined the layer stiffness to be used and the subgrade CBR or subgrade stiffness modulus. 

In all the design charts, the foundation layer is constructed of the same material (single foundation layer) materials are as those described in Table 13.7. However, it must be noted that the use of granular sub-base. Type II (for details, see Section 10.5.2), is not recommended for any pavement design for more than 5 msa. 

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