need to put a 3m x 1m hole through a concrete floor

and? your question is? Well you could do,but i recommend you use a mallet & chisel as you have carpentry and joinery as your top ranked skill on your profile............... good luck with that chris ;)

Let us know how you get on.

I should use a tape measure first and mark it out for accuracy is it a deep round hole or oblong (just remembering the song) kelvin

sthil saw with dust supression tank to cut hole neatly. then hire a bosch electric kango hammer to take the hard work out of it.