Two: To get them to soak into the concrete far enough to reach the urine, which would be in pretty deep. Bleach uses oxygen to break down the urine. It will work also if it can reach the urine in enough concentration and for a long enough time to work (which for oxygen is fast). read more
Usually this is harmless, but not when it comes to pet urine. Dog or cat urine can seep deep within concrete; and anyone who has had cats or dogs knows that animal urine can be difficult to get rid of from your garage floor, basements and under carpet pads. read more
Unsealed concrete tends to hold in dog urine odors because it is porous and the urine is able to seep deep into the actual concrete. If your dog has been urinating on your concrete patio, driveway or porch, you will have to do some deep and thorough cleaning to remove the smell. read more