Getting urine odor out of concrete. Concrete is porous and urine will seep deeply into the pores and be difficult to remove. The specific steps for removing urine odor from concrete, as with most surface's, depend on the circumstances. The main questions to be answered are how sever is the contamination? And how porous is the finish of the concrete. Slick finish or a finish made to seal the concrete, or hardened concrete allows very little urine to penetrate it. These finishes are usually found when concrete is the final surface or the finished surface intended to be seen. Concrete that is going to be covered by carpet or some other floor covering is usually more porous. This allows urine to penetrate deeper into the pores of the concrete. It becomes more difficult to reach and the process takes longer.
For heavy concentrations of urine start by washing the concrete with a good acid side pretreatment. This will break down lipids (animal fats) and alkaline salts present from the urine residue. This will remove a large part of the urine quickly. This pretreatment can be presprayed on then give it time to work and rinse off. Or it can be mopped on and rinsed off with clear water. Following this acid side pretreatment wash, then follow up with heavy application of a good urine enzyme product. Allow this 2 or even 3 days to penetrate deep into the concrete and then come back and rinse or mop with clear water. The enzyme product needs to be kept wet for the entire time so the enzymes can digest the urine odor residue and neutralize it. It needs to come in contact with the urine and stay wet or damp long enough to work. In the case of concrete it needs time to penetrate and then work. You can repeat the enzyme treatment if needed. You can also finish this process with a good sealer (shellac, varnish or acrylic sealer) to seal in any remaining urine odor.
If you are working with a smaller area or you do not have the time to wait for an enzyme product (2-3 days) I suggest you use a good urine oxidizing chemical. These are also effective if you don't have the 2-3 days.
Use plenty of ventilation with any method. Gasses are being created that should be diluted with fresh air and ventilated to the outside.