Will grass indoor/outdoor carpeting ruin concrete?
Q. If I do not glue my grass carpeting to concrete, just roll it out, will it ruin the concrete?
A. No, the indoor/outdoor carpeting will not ruin the concrete. The concrete may darken under the carpet from the moisture the carpet traps in the concrete, but it will lighten up after the carpet is removed.
You may want to try wetting a part of the carpet to make sure no color bleeds through the carpet. That would be the only concern I would have.