Yes, in most cases you can apply C2 Salt Safe to a previously chemically cured floor.
If the concrete still absorbs water, it will also absorb the product.

To test this, pour a little water on the floor, wait a few minutes and wipe off the rest.
If the place darkens - the concrete has absorption and the product will work properly.
If the water stays on the surface and does not penetrate, contact us - we will choose another method or solution.