How to calculate the effect of ground Enhansing material (GEM) in Earthing

[JanaWick]

Can anyone advice me on how to take in the effect of Ground Enhansing Material (GEM) used in Electrical Earthing to reduse the earth resistance? in all the suppliers specification they only mension the GEM reduse the soil resistance drastically? so should i consider 1/5th,ro 1/10th or 1/100th of the given soil resistance?

or should i just consider the whole earth as a earth mat covering the full area coverd by GEM?

 

[Electro-tech]

How to Improve Resistance to Ground - Technical Articles - https://eepower.com/technical-articles/how-to-improve-resistance-to-ground/#

 

[JanaWick]

How to Improve Resistance to Ground - Technical Articles - https://eepower.com/technical-articles/how-to-improve-resistance-to-ground/#

I have gone through the article. However, it has no reference to the use of GEM.
for example the ERICO GEM as per the attachment has a resistivity factor max 2 ohm-cm how do we incorporate this into the formulars in calculating the earth resistance