8 years ago I used 2 coats of ghostshield 4500 densifier + 8510 silane/siloxane to waterproof a covered front porch with finished living space below. It was a broom finish and I only got half the coverage that they advertised, so if you have a broom finish beware.
The porch faces north and is...
I sealed concrete countertops with tung oil. It did take a while and quite a few coats before it stopped absorbing in. Then it decided to weep out of certain spots for a couple weeks. Full cure took a couple months. It is not a topical coating, and if you try to build up a topical coating it...
I would not put MDF in a garage. It will swell with humidity changes and eventually all of the joints will deteriorate.
I am dealing with that problem right now in my mudroom with thermofoil finished mdf cabinets.
I have the harbor freight one. It works very well. I normally wait until I have 5 or 6 chains ready to sharpen before I break it out. It won't touch the rakers though, so I still need to flat file or dremel those.
Very similar setup at ~950 ft long. Paved over a base of millings. Cost was $18k 4 years ago. It took them a full 2 days working about 10-12 hrs per day.
The difference is the concrete being in tension vs compression. It is very weak in tension, therefore much more prone to very catastrophic failure when not desihned and built properly.