You first unlock the Concussion Tower during level 05.
One of the easiest ways I have found grind these types of achievements (if its for a tower type you don't use) would be to play level 12 on Practice on Easy (I believe you can play any level at any time you want, feel free to correct me if I'm wrong.)
Even on Story Mode, you can essentially beat the level with just the 8 tower spots around the core housing, and maybe one tower blocking the quickest route.
I build 3 cannons along the side closest to the ship, a concussion on the single spot near this, a temporal on the spot across the road, and then at least one tesla among the other 3 spots.
When the level is nearing its end (1-2 waves left) just fill as many spaces as possible with the tower you are working on.
I was able to get at least 50 of the tower I was working on on any particular run (and that was on Story Mode - less resources)
You can do something similar on any level when you finish as long as you remember. This is just for if you are solely trying to grind out this achievement.
As with all other achievements in this game, this achievement will not unlock until you finish the level.