Yes David's right I spent 10 years putting images on to a variety of surfaces, predominantly vehicles or painted metal sheets.
I never tried concrete but it wouldn't be any different to wood, where the problems are the porosity of the material used. I would suggest sealing the surface with a clear-coat lacquer, we always used a 3 pack from Glasurit. This would need to soak well into the concrete, and two or 3 coats given to ensure it's well sealed, then left to dry fully for a few days- as long as possible. Before coating with photo-emulsion you would need to prepare the surface with 600 grit Wet & Dry paper to give the surface a key for the emulsion.
The emulsion will have to be sprayed to coat an 8ft x 5ft surface, this takes a bit of skill getting the right consistency etc to coat evenly, and ensuring it sets as you spray. We made our own emulsion, and also trialled Ilospeed Gd3 emulsion for a short spell. Our enlarger was a modified De Vere 54a mounted in a cradle, we custom built a condenser light source with a 275W bulb and typical exposures were around the 2-3 minute mark for an 8ft long image using a 150mm f5.6 Vivitar VHE lens (actually a Componon) at f11-f16. Your negative needs to be slightly higher contrast/gamma for these sizes.
We didn't dry the emulsion before exposure/processing, but we added extra hardeners etc to the emulsion & the developer, the alternative is to let the emulsion dry overnight, usually takes around 12 hours to air dry. Again you will need to spray the dev, stop & fix, garden sprays are ideal. Developer will need to be modified, we always used Ilford PQ Universal or May & Baker (Champion) Suprol, at 1+19 dilution (instead of 1+9) with additional Sodium Sulphite and hardener. The sulphite helps prevent aerial oxidation as the emulsion isn't totally immersed in developer, and using the dev more dilute makes it far easier to get even development. We fixed with Hypam again more dilute than normal. We washed for 3 hours, but an hour is sufficient if the emulsion was dried prior to processing. We used a washing rig made up using crop spraying parts from an agricultural supplier.
You will have to ensure that no chemicals or water are allowed to soak into the rest of the concrete and there will be a considerable volume of liquids to drain away. When the image is finally washed and dried then you will need to coat it again with the Clear-coat lacquer.
All spraying of lacquers, emulsion etc should be carried out with airline respirators, googles etc, and you will need fume extraction. Processing can be done with a respirator.
It's a far more daunting prospect than it initially appears.
Ian