A stray cat has been whizzing on my concrete shed slab for months in one spot (all winter). So far I've done vinegar that I poured on it and let dry overnight. I know that works well for cat urine on fabrics. Planning to cover with baking soda paste and brush it around today and once it dries I'll sweep it up, soap water mop, then bleach mop. I figure the ammonia will be neutralized or diluted by then, but if not I can leave it to dissipate. Any better ideas or is this about it? I could seal it in, and I may eventually do that, but want to avoid if possible.