All of our concrete encased electrodes consist of a GEC sized Cu with >20' encased. Rebar is not acceptable here in SoCA.
Acorns have been accepted for tying the Cu to ground rods, etc. although there must be access to them after the installation, unless "DB" listed, in which case they can be buried. We usually use exothermic welding to attach them to other parts of the electrode system.
To use tie wire to tie them together would undoubtedly get us a correction notice.
