a decent size hammerdrill will make the holes with no problem, but if you
drill too close to an edge, the slab may break off.
Depending on the thickness and strength of the slab pieces, you may need a
setback of 6" or more.

If you want reasonably straight edges, it would probably be best to score
the smooth side of the slab with a wet concrete saw and then break with a
hammer.


ps Seems like an awful lot of work.

Bill

"HotRod" wrote in message
...
I'm working on a retianing wall project that involves using busted up old
concrete slabs. I need to drill a ton of 3/4" - 1" holes as the blocks get
higher, any ideas? Also ideas on how to crack the 4" thick concrete where
I need to? Do you think a peice of angle iron and a sledge is best?