Asbestos watch - looking for sense check

Morning all (and what a lovely morning!),

we've recently moved into a 60s house - and the back garden is about 80% covered in concrete. Our plan is to lift it all, and eventually get the back area turfed.

This morning I started lifting some bits of concrete - and found something a little unexpected. The top layer - around 2cm thick - is pretty standard looking concrete. But under this is a second layer - around 8-10mm thick - which feels more like some kind of board. It breaks easily but into quite large chunks. Under this is then some general granular material.

What's the middle layer? I'm cautious given the age of the house - and this concrete has probably been there since the 60s - so I'm always aware there might be asbestos kicking around. But any reason this would be used in a garden - I can't imagine so.

I've included a pic of this substrate - you can see it looks pretty much like another layer of concrete - you can see the small bits of aggregate in it.

Any ideas what it might be? It may well be standard for this age and application for all I know.

Many thanks
Keith

If you've got a sample you can double bag it and send it for analysis

Im all for getting a test done and Passuk supply everything you require to send a sample for testing. From the picture that doesn't look a regular thickness for a manufactured board and looks to contain aggregate.
Edit: or are you referring to the dark area in the background , if so post an in focus clearer pic because that looks a more uniform pattern

Thanks for replies - I'm talking about the foreground material - agree, it's probably just some kind of concrete. It did occur to me that maybe - at some point - this was the original upper surface, and then somebody then overlaid it with more concrete.

I suppose my question was - would anybody ever use ACM in this setting? Find it unlikely - its purpose was as fire retardant partly, and as a standard board product.

It's certainly not fibrous or fragile in any way - so would probably fall into a non-friable type even if it were (which I'm now thinking it's almost certainly not).

K

When wet it will not raise dust so much safer than when dry, but still need to wash hands well. If it was asbestos it would definately be fibrous when it breaks.