Nick H wrote:

Conrete mixes can vary greatly depending on proportions used, hand
mixed or machine, or readymix etc etc. Once its full cured thats it.

Interesting. You learn a lot about how to lay concrete by breaking up the
old stuff. It's a patchwork of different bits laid at different times
(which is why I'm breaking it up).

The hardest stuff to break up is the oldest, but thats because its a sandy
colour and softer - the breaker point just goes through it without causing a
crack. I assume a weaker mix?

The harder stuff breaks easier because it cracks. One area has 6" of solid
concrete with no hardcore or sub base beneath it, that breaks really easily.
Another was laid on really large hardcore - whole & half brick sizes - that
also breaks easily.

Toughest stuff is that properly laid on smaller compacted hardcore, really
tough.

Just goes to show that if you do it right it really is stronger.

When you have to break up some concrete you never know how "easy" its
going to be until you start, some you win some you lose.

It's been a good learning curve!

You can leave behind all the small stuff, its perfectly OK as fill.
You can in fact buy crushed concrete as a fill material.

Good, just off to hire a wacker plant to compact it in.

Thanks

Dave