The Brew Cabin

Posted: **Mon May 17, 2010 5:06 pm**

I have recently removed a section of patio flags around our conservatory returning it to grass, which is all growing fine.

However the recovered flags + a few more (generally 600mm x 600mm concrete flags) are going to form an extension to the existing patio (actually filling in 3m gap between patio and fence).

For the sub base I was intending to re-use the recovered DTp 1 sub-base (was about 4 inch deep) and broken up hard core + purchase more DTp 1 . The hard core consists of the broken up 2inch concrete bedding layer and peices of slab that didn't come up whole. Most of the hard core is no bigger than say 50mm pieces due to my hard work and Mr SDS breaker.

I have currently dug 8 inches deep (1.5" flag + 2inch bedding + 4.5 sub base).

I have read conflcting information about using hardcore ? (I assume a no no for block paving + sand badding layer).

Currently I put a 1 inch odd layer of DTp1 down, covered with hard core and hand whacked it down (into the DTp 1), but does need 1-2inch more DTp1 to make the levels (+ hire of a plate compactor).

Can or can not hardcore be used under concrete flags with 2inch cement bedding ?

Posted: **Mon May 17, 2010 9:11 pm**

It's not ideal but if you compact and blind it enough it will be fine as long as it's for light pedestrian use only.

Posted: **Mon May 17, 2010 9:25 pm**

Thanks.

Its just that the last patio I built was in early 90's at outdoor hostel, where budget restraints meant trying to reuse as much material as possible. We broke up the concrete slabs as small as possible, hand whacked down into 1 inch bed on sand, covered and whacked with finer stones (actually crushed limestone + dust from local quarry), then two inches of mortar and finally sandstone flags. 20 years later still there, not aware of any stones coming loose, though the slabs to the front door show clear signs of wear.

The Brew Cabin

Using "hardcore" for sub base ?