Concrete encased electrode?

[Cu>Al]

My first post; please be nice...
Please revisit the NEC definition of "solidly grounded". "Grounded, Solidly. Connected to ground without inserting any resistor or impedance device."

From AC Power systems handbook 2007: "The Ufer ground takes advantage of concrete's natural chemical- and water-retention properties to provide an earth ground. Concrete typically retains moisture for 15 to 30 days after rain. The material has a ready supply of ions to conduct current because of its moisture-retention properties, mineral content, and inherent pH. The large mass of any concrete foundation provides a good interface to ground."

Not only must it be in a foundation it should be at the bottom of the foundation.
The straightness and shortness of the electrode conductor have to do with the impedance.

More from the AC Power systems handbook: "Conductors interconnecting sections or components of an earth ground system must be kept as short as possible to be effective [9]. The inductance of a conductor is a major factor in its characteristic impedance to surge energy....Furthermore, any bends in the conductor will increase its inductance and further decrease the effectiveness of the wire. Bends inground conductors should be gradual. A 90° bend is electrically equivalent to a 1/4-turn coil. The sharper the bend, the greater the inductance.

If your structure is on a foundationless slab you will have to drive ground rods

 

[Steve16]

Foundations also require dampproofing which isolates the soil from the foundation. Footings are below this dampproofing