A Plain Jointed Concrete Pavement is to be designed using the AASHTO 93 Pavement Design Method to withstand a traffic of 10,000,000 ESALs. The slabs are connected longitudinally and transversally using dowel and tie bars and asphalt shoulders were used. The geotechnical investigation conducted before the construction indicated that the subgrade is composed of clay with high plasticity (Class CH according to USCS) and that the bedrock layer was found at five feet from the surface of the subgrade.

The following information and design assumptions are available:
• Concrete slab: Ec = 3.8x10⁶, S's - 650 psi
• Unbound Granular Subbase: DsB = 12 in., Esb = 30,000 psi.
• Resilient Modulus of the Subgrade: MR = 4,000 psi.
• Initial Serviceability index value: p; = 4.5
• Terminal Serviceability index value: p = 2.5
• Reliability and Standard Deviation: R = 90% and So = 0.3

The quality of the drainage is good and the pavement is exposed to moisture level approaching saturation for 15% of the time.

Determine the thickness of the concrete slab to withstand the projected traffic. Assume reasonably any missing information and justify your assumptions.