What's up with you guys always using chlorine/bleach solutions? Because it's cheap? I don't claim to be a chemical expert, but I'm well aware of what bleach does to certain substrates & organics. Why not use a d-limonene dilution or other degreaser?
I do not do a ton of concrete work, but enough to know it's fairly easy. I agree with Texas, if it hasn't been done in a while the customer should be extremely happy with the results, via conventional method.
Cooper, I use a turbo for the gum removal and pull it way back to clean along building edges, obstacles and wherever I can't get with my surface cleaner. Then I spray whatever cleaner the job requires, use my surface cleaner with hot water and then rinse & cleanup all the debris. (By the way, this is for storefront work.) Do you see an issue with this process?
Acids? ESPECIALLY not in a high pedestrian traffice area - even if you're doing outside of normal business hours. Unless you have some sort of containment system, I would worry about residual and unexpected vehicle or pedestrian traffic. This type of job doesn't require caustics. HOWEVER.....on occasion we use ABR X-180 Weathered Wood Restorer if we want an especially "bright concrete" result. It contains Oxalic & glacial Acidics as well as detergents, surfactants, etc. It does have to dwell longer for the result which may not be practical for most commercial situations, on patios, garage floors, driveways for residential, where you may charge more for the service, it works really well.
My 2 cents worth!