Earthen floors and varmints or rats???

I want to know if rats can penetrate an earthen floor?

or can penetrate an earthen floor that has cement added in the mix?

The floor doesn't keep rats out.  Not having things rats want in the space keeps rats out They are unlikely to come up through an earthen floor that is properly set on the earth.  Rats are not really burrowers. They are more likely to get in through a hole for plumbing, or around a window or door. A good foundation and a properly lain floor will make the floor rat proof.

We have pack rats and pocket gophers, and haven't had a problem with burrowers coming through the floor.  Physically they could penetrate the floor, but they don't seem to have any desire to burrow under and around the foundation footer and stem wall.

If you were really worried about it you could lay a chicken wire mat before building the floor base.