There is a felt joint in the middle acrros my garage floor. It is
fairly rotted and soaked with automotive fluid after years. I removed
it all with a screw driver. Then used a 5/8" foam filler rod and
silicone caulk to fill the gap. This fixed the cosmetics but now I
was thinking maybe I did something bad, should I reinstalled a piece of
new felt? Is the whole slab going to move and cause problems? The
garage is 20 years old.

If I get a new piece of felt how do I get it in the joint properly?

Thanks ina dvance