How do i backfill a trench so paving does not skin

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ringi
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Joined: Tue Jun 07, 2011 10:32 am
Location: Stockport, UK

Post: # 82101Post ringi

I have a 3 foot deep water pipe trench under where the new path is going. It is wider then I would like as the clay on one side collapsed with a crack the rain filled up over the last few days. (I saw the crack so helped it on its way for safety) The trench is about 3 m long under were the paving is going.

I am going to use Granite Paving 300 x 300 x 25 on a semi day mortar bed over well compacted 150mm MOT.

I could hire a trench rammer and try to put the clay back it, but I have not used a trench rammer before, am put off with the weight, and I don’t know if it will get the clay firm enough.

Otherwise I am thinking of backfilling firstly with about 6inches of drain bedding then MOT – I have a manual rammer I can use to compact it. The trench is not wide enough to get a plate compactor into.

Am I thinking along the right lines…

Should I dry mix a bit of cement into the MOT encase I don’t get it compacted well enough? (I will also have grit stand and 20mm limestone or “all in one� on site if they would be better.)
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Dave_L
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Post: # 82103Post Dave_L

A trench rammer would be best but if you can backfill in 100mm lifts with your stone and compact with your manual rammer as you go, you won't go far wrong.
RW Gale Ltd - Civils & Surfacing Contractors based in Somerset

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local patios and driveway
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Post: # 82114Post local patios and driveway

Take any loose clay out and add 150mm of mot in to the gap, hire the trench rammer (its a tool my missis could use) compact, then wet with hose. Repeat until at height required. This will do the trick. Terram at bottom of hole would also serve to improve your chances
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lutonlagerlout
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Post: # 82118Post lutonlagerlout

i thought if you just stamped on it with trainers it did the trick?
LLL ???
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ringi
Posts: 125
Joined: Tue Jun 07, 2011 10:32 am
Location: Stockport, UK

Post: # 82151Post ringi

I just done a quick calculation, the cost of the cement for a 10:1 “no fines� mix would be less than the cost of renting a trench rammer and I own a cement mixer. I expect the stone costs for “no fines� will be about the same as for compacted stone.

Therefore is there any reason not to fill the trench with a week mix no fines concrete, then top of with MOT compacted with a plate compactor? (I also own a plate compactor, as cheaper to buy and resell on ebay than to hire)
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London Stone Paving
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Post: # 82152Post London Stone Paving

lutonlagerlout wrote:i thought if you just stamped on it with trainers it did the trick?
LLL ???
Depends on the brand :;):
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Mikey_C
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Joined: Mon Oct 30, 2006 8:24 pm
Location: Bournemouth, Dorset

Post: # 82169Post Mikey_C

ringi wrote:I just done a quick calculation, the cost of the cement for a 10:1 “no fines� mix would be less than the cost of renting a trench rammer and I own a cement mixer. I expect the stone costs for “no fines� will be about the same as for compacted stone.

Therefore is there any reason not to fill the trench with a week mix no fines concrete, then top of with MOT compacted with a plate compactor? (I also own a plate compactor, as cheaper to buy and resell on ebay than to hire)
yeah that will be fine.
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