Mystery concrete.

[mormop]

Hi all,

I'm in the process of laying a patio and have been lifting the existing slabs which are 900x600x50mm council grey and are laid along the back wall of the house. To the right of house is a gate, and as you get near to the gate, the council slabs change into 600x600. I was trying to get a pick under the slab to lift it like the others but it turned out to be considerably more than 50mm thick. It looks like the last three slabs are actually poured concrete.

Picture here, yellow arrows show extent of underground part of concrete slab:

http://cubeupload.com/im/JrXQbH.jpg

Is there any reason for this or did Barretts (18 y.o. house) just need somewhere to dispose of some excess concrete?

I don't really want to go ape with a chisel on it if it's there for a reason for it being there but I can't think of or find any obvious reason.

Any comments welcome, thanks.

 

[mormop]

Sketch of the house available here:

http://i.cubeupload.com/St8vf6.png

The only thing I can see of any note about the positioning of the poured slabs is that they're at the bottom of a slope. Aside from that there doesn't seem to be anything special. They also appear to have sunk at the left hand end by about an inch and a half but as it's 18 years old, this doesn't seem an uncommon occurrence over that long a period.

 

[Deluks]

Could be capping something off, a soakaway or old well? Only one way to find out, keep digging!

 

[mormop]

Must admit, I hadn't thought of that. The site was a school before the houses were built and brickworks before that. The part we're on was out of bounds during the school years and seems to have been backfill from the brickworks.

What I may do, is get some steel bars and hammer them at an angle under the concrete slabs to see if it breaks through into a void. If yes, think I'll leave it well alone and formulate plan B.

Many thanks.

 

[JohnD]

dig a pit beside the slab, then you will see how deep it is and what is under it.

It wasn't a Catholic school, was it?

http://www.thejournal.ie/readme/mass-grave-galway-tuam-1494001-May2014/

 

[mormop]

Decided to carry on with the pick and found that they are indeed slabs but they've been laid onto a poured slab concrete block that looks like it's stopping the sloping driveway from inviting itself into the garden.

Lifted the slabs and it looks like the patio will stop short and there'll be a gravel area on top of the concrete block.

Thanks again.