Sub-base material

[Kylethompson30]

Hi,

Our garden is currently covered in decorative stone similar to ones sold in B and Q called Blooma Golden Brown gravel decorative stone ranging from 10-30mm in size.

We have been sieving out unwanted mud through a 10mm sieve and now have the stones in bags. We are wondering whether these stones would be ok for a sub-base for a calibrated limestone patio?

We also have the old concrete slabs which we will be taking up. We could break these into pieces and use these if more suitable? Just trying to avoid buying more materials.

Many thanks,

Kyle

[lutonlagerlout]

you could mix it in with the sub base material but on its own gravel is just gravel :;):
Type 1 is relatively cheap
so I would mix it in and compact properly
cheers LLL

[seanandruby]

You have demonstrated how time consuming it is to seperate matetial, it would of been a lot quicker to get rid of the stone and replace with hard core/mot. We had to relay a permeable car park once and it took days, weeks to pallet them up ready for re-laying, they were moved, moved again and again so we could do drainage, a right farce. We could of ripped them out with the 360 and got new ones in and it would of worked out a lot cheaper. If it ain't clean, bin it, sometimes easier :;):
As for the slabs, you would need to break them up really small pieces to and mix with fines like sharp sand before compacting.

[Tony McC]

That gravel is exactly that: a gravel, and as such is not anything like a Type 1 granular sub-base. Sub-base aggregate needs a very specific size range to generate the interlock that gives it the load-bearing strength required - see Sub-bases page.

And the same goes for broken-up flags and bricks - there's even a FAQ

If you're desperate, then you *could* use broken-up flags and fill the gaps with gravel, as a sort-of sub-base for a light-use patio, but it will *never* perform as well as a proper sub-base. The best option would be to scatter the broken-up flags (pieces no bigger than 50mm - that's a lot of work in itself!) as widely as possible over the patio area, then scatter the gravel similarly, and finally get some genuine Type 1 or Type 2 granular material and use that to complete the sub-base.

It would be a shame to spend all that money on calibrated stone only to see it ruined in a year or two due to settlement of a bodged sub-base.

[Kylethompson30]

Thanks everybody. Will use type 1 based on your advice. The use of the gravel/clippings was to save the effort of disposal but will try free to collector on a few platforms which will hopefully save me a skip or trips to the tip!