Unpleasant, ammonia-like smells wafting up from a concrete surface are a telltale sign that cat urine is present. Although you may have already cleaned the urine from the surface, some may have been absorbed into the concrete. Despite concrete's hard, durable surface, it's also a highly absorbent material and cat urine left unattended is slowly absorbed. By drawing the urine stain out of the concrete, you can effectively get rid of the accompanying smell.
Hose down the concrete surface enough to wet it.
Combine 12 per cent hydrogen peroxide and talcum powder in a bowl to make a thick, spreadable paste. Apply the paste to the concrete, at the site of the cat urine smell. Use enough paste to completely cover the smelly area to a thickness of 1/2 inch to 1 inch.
Allow the talcum powder paste to dry on the surface of the concrete. As it dries, the poultice paste will draw out cat urine that's been absorbed into the concrete. Scrape the dry paste off the surface to remove it. Dampen a scrub brush with water and scrub the concrete to remove any remaining dried paste. Blot the surface with an old towel to remove excess water.
Treat remaining cat urine smell by pouring pet odour neutralising crystals over the damp concrete surface. Cover the smelly area with a generous amount of the neutraliser, then allow it to sit overnight. The enzymes in the neutraliser break down proteins in the urine to get rid of odour-causing bacteria.
Sweep the pet odour neutraliser into a dust pan and discard in the trash.
Blot up a fresh cat urine stain as soon as possible and follow by washing the concrete with detergent and water. If you're unable to tend to a fresh urine stain right away cover it with an absorbent, such as sawdust, cat litter or baking soda. Sweep up the absorbent later, then clean the concrete with detergent.
Leaving urine stains unattended sends a message to the pet that it's acceptable to urinate in that area.