Cutting concrete block

use masonary blade in circular saw, perfect cut but dusty.

dont block those windows in a fire how would one get out?

ventilation?

its never a good idea to elminate windows.

Done it many times with both a chisel and a masonry hammer which has a chisel on one side of the head, also a 3 pound hammer will do it, but not so neat. You carefully tap along the line where you want to cut the block on both sides, you will note that it has a ringing sound when you hit it, you keep going over the line rotating sides, until the ringing sound turns flat as the crack grows, once more over the block and it should part. It sounds like you are trying to cut it too hard by hitting it too hard, it really doesn't take much tapping once you get the feel for it. If you find that you cannot successfully cut a block, most concrete block plants make half blocks that you could use.

Do you have the right kind of block? Blocks intended to be split have a void in the center. If the web in the center is solid you don't have the right block. There are actually at least 4 kinds of 8x8x16" blocks not counting specialties.

Why would you even want to do this? Just buy some 8x8x8s. Go to a real masonry supplier and you will be surprised by what they have to make your life easier.

I have cut bricks with an angle grinder and the apropriate blade in it. I suspect that would also work here.