anyone ever use tamped dry mix concrete under a dry laid brick patio to prevent setteling? sand usually gets a low spot after a few years. my soil type is red clay and not expoaed to low temps for long periods. was thinking of 1-1/2″ thick concrete under a 1/2″ of sand, then lay brick and water it in.
This compact detatched accessory dwelling has an efficient layout with a vaulted ceiling that enhances the sense of space.
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No, but how about something similar?
Here is my method for installing a permanent paver project:
Excavate the area to firm soil and fill with ABC gravel - also known as crush-n-run or roadbed gravel. If you want you can put a geo-textile fabric under the stone to help keep it in place. They sell this at home improvement stores – one brand is Typar. A small amount of mortar mix or Portland cement can be mixed in with the crushed gravel. I use a concrete mixer. Maybe 2 or 3 shovels full of the cement product per wheelbarrow of stone aggregate. The idea is that the aggregate still needs to drain, but the cement makes it so that it is a little firm so that it cannot erode. Compact the aggregate mixture in place with a vibratory plate compactor.
Then use a 1" or so layer screenings as a bed for the pavers, again mixing in a small mount of cement. The screenings are like course sand that is made of crushed stone, sometimes called fines. It compacts together a little better than sand.
Lay your pavers.
Cover with mortar sand (fine sand) to protect the pavers and run the plate compactor over it again. Then, when you water it in, the sand will go down in the joints some, depending on how large the joints are.
At this point if you want you can sweep poly metric sand into the joints and mist only slightly (important) with water. Polymeric sand is expensive but kinda sets up, and is more impervious to weeds – it is a great product.
Finally, when building a paver project is very important to create a hard edge to contain the pavers. Various things are used for this: Metal strips that are staked to the ground are very common. Big box stores sell plastic edging and probably the metal too. 4x4s or 6x6s staked down with pieces of rebar works well. Or even a concrete edging can be used.
A note about the designation of crushed stone aggregate products: Naming conventions are very regional and often controlled by the state highway department since the state DOT is most often the largest user of these products. So, for example, what we called ABC here (3 stone products mexed tigether) is likely called something else where you live. The best way to find out about this is to call a quarry and ask what stone products they sell and for a description of each product.
If your base is poor, even a properly re-inforced concrete pad can develope those same problems over time. You need to have about 18" of compacted mineral base, followed by sand or stone dust.
Interesting...
Thanks. Now that you explained it maybe I can remember it... :-) When I order that kind of stone I would normally just say 'ABC' since that is the NC-DOT designation. Also the crush-n-run might be a southern colloquialism.... like "corking", you know, that stuff the painters put in the cracks of woodwork with a gun before the wood is painted, or "corn corners" that brick detail at the corners of more expensive houses (quoin corners), or like "facial" which is that board the gutters are nailed to. ;-)
I tend to agree w/ Piffin ... the problem of a poor base will not be solved by some concrete mix below. Sand should be good ... it doesn't compact much so if you have some settling look below the sand. Tamp a good base and put sand in for leveling and you should have many years of good service. Otherwise you are wasting your time.
They use pavers here specifically for places where the base sucks. Pool decks are a good example because it is hard to get decent compaction on the back fill without breaking the pipes. With pavers you can pop out the ones around the sink hole, pack in fresh sand and put them back. Better than a cracked concrete deck.