My neighbor noticed what I was doing and told me he found the same problem and
that I should rent a hammer drill. He had done that and loaned me his drill bit
for the job. Nice to have good neighbors.

I assume a bunch of holes to weaken the thing is called for. How far apart
should I space the holes to minimize the amount of sledge work I will have to do?

Is there a pattern of sorts I should use? Any tips, tricks or even hints to make
this little exercise easier would be appreciated.

Thanks!

Yeah, you could do it with an ordinary hammerdrill and masonary bits, but a combo-drill will do it a lot faster.

A hammer drill spins like a normal drill, and when it finds resistance, a "Hammer" strikes the bit, causing the rock to crack a bit and allow the bit to continue on.

A combination hammer drill accepts jackhammer style chisels as well as masonary drill bits. This allows it to work like a normal jackhammer aswell as a drill.

Or you could just rent a small electric jackhammer.

If you decide to go normal hammer drill, get a contractor or industrial grade one, rather than one you could buy at a hardware store. They aren't really made for rock.

1. Hammer drill or carbide bit in regular drill
2. Rotary hammer - even the largest will be slow
3. Chipping electric jackhammer (35#) - AKA small electric jackhammer - used from a standing position. Not heavy enough to do the job.
4. Pavement breaker (60#) suitable for concrete slab or rock penetration. Rental is about $40 for 4 hours which is longer than you will need it or want to use it anyway. Also used from the standing position.

While you are at it, buy a rock bar ($20) to pry out the pieces or break small pieces away where the jackhammer won't fit. I have 2 of these and they get used frequently.

I also urge you to have a pickup or trailer backed up to your work site so you can load the concrete as you go and haul it straight to the dump. Otherwise it will come back and haunt you.