I have areas in my yard that are forever over-grown with weeds. I’ll pull them out only for them to return weeks later. I don’t want to grow anything in these areas as they’re paved areas that look better paved. Is there any legal substances that can be applied that will render the area useless for plants/weeds to grow in forever. I thought salt might be good but that hasn’t really done anything. Round Up and similar products kill the weeds but they still come back.