Question $2$

Given, $W_{18}=20{10}^6,R=85\%,So=0\mathrm{.}30,Sc=600,$ and $\frac{\frac{?}{{?}_{\frac{?}{?}}}}{P}SI=2\mathrm{.}0,Ec=6{10}^6,K=300$pci, $pt=2\mathrm{.}5.$ The pavement is JRCP with tied asphalt shoulders. In addition, the drainage conditions are fair with $25\%$ of the time the pavement structure is exposed to moisture level approaching saturation.

Determine the required slab thickness$($D$).$