# weaving and cracking soil



## dave c (May 6, 2010)

Constructing an earth embankment for a new bridge with fill up to 27 feet. We have been using material that was provided by the owner and passes as common borrow. The material is slightly damp, we are able to compact and our trucks can drive on it, but the area looks like jello it is weaving and cracking. The soils inspector has told me it is getting at least 95% compaction. Will this material ever tighten up? Maybe over time?


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## tgeb (Feb 9, 2006)

It really depends on what the material is.

A damp clay can reach 100% compaction and rut and pump like crazy, if the surrounding soil is wet it may never get tight.

Maybe you could "bridge" it with some better material.

Welcome to the site. 
Add your location and we can assist you better by possibly knowing a little bit about what the local conditions might present you.


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## rino1494 (Jan 31, 2006)

Is the soil at optimum moisture ?? Is it pumping all over or in certain spots ?? Sometimes you will get a bad spot that you need to dig out and re-fill and compact.

It is amazing, you can get bubble gum type material to compact to 95%.


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## ch0mpie (Nov 30, 2005)

The material may tighten up but that sounds like it would be a disaster for the bridge. Could be a regional thing but by me common borrow or common fill would not be used to carry any significant loads. An enbankment for a bridge would be structural fill and ussually would allow a maximum of 15 or 20% fines. You can still get 95% compaction on poor material. Have they taken any samples for sieve analysis? Are you placing the material on the wet or dry side of the compaction curve? What is the owner's engineer saying about all this?


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## dave c (May 6, 2010)

*additional info*

The material is being placed under a proposed road not the actual bridge footing. The material does have less than 15% fines in it and is not just in isolated areas. The owners engineers have ok'd the pile for use possibly because the owner wants to get rid of it. I am sure we are placing it slightly on the wet side of optimum but again today compaction tests showed at least 95%. It also appears that there is some organics in this material which might add to the problem


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## dayexco (Mar 4, 2006)

dave c said:


> The material is being placed under a proposed road not the actual bridge footing. The material does have less than 15% fines in it and is not just in isolated areas. The owners engineers have ok'd the pile for use possibly because the owner wants to get rid of it. I am sure we are placing it slightly on the wet side of optimum but again today compaction tests showed at least 95%. It also appears that there is some organics in this material which might add to the problem



i sure hope you're good at documenting all the discussions you're having with the owner and the engineer. if/when there's a failure in the future, you don't need to have that engineer stand up in a courtroom and say....well, he should have read the spec book.. we'd never allow that.


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## tgeb (Feb 9, 2006)

I agree with Dayexco, make sure you cover your own ass.

I was involved with a parking lot/entry repair that was covered with pavers (10K square feet) that had to be removed/trashed and the sub grade redone due to poor soil and reused material being placed and compacted, everything was fine with the installation till the weather got to it, (Spring thaw and rains), the whole place turned to crap. 

People were dragging their BMW's and Mercedes over these rutted up drive lanes into a fairly fancy restaurant.

The excavator that did the sub grade was being blamed for the failure of the sub grade.....it would have cost him in the 250K - 350K for repairs and loss of income for the restaurant.

He had a change order (credit to the GC) for reusing stone that was onsite, (old farm driveway), as opposed to using new stone that was in the contract.

Had he not taken good care to document the changes, he would have been on the hook big time. 

It was the GC who claimed the Excavator had done wrong.

Watch out... the inspecting firm has zero responsibility...you should see the disclaimers in their contracts. :sad:


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## ch0mpie (Nov 30, 2005)

your right about the disclaimers but if there is really a big problem inspectors will hang too. That being said you need to have your ducks in a row dave, a road embankment can carry signficant loads. I'd be worried about a slope stability issues as well as the settlement. How was the subgrade before you started placing fill? 15% fines but some organics?? something doesn't sound right...


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## dave c (May 6, 2010)

i agree with all of you. Letters have been written to document our concerns. ANy experience if this material will tighten up over time


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## PipeGuy (Oct 8, 2004)

dave c said:


> ANy experience if this material will tighten up over time?


You haven't provided enough info about the soil to make that kind of judgement call. Mine / job location? Soil weight? Soil classifcation?
With enough work any soil can be dried to a point where it stops pumping. That won't neccesarily make it stable or otherwise suitable for bearing a particular load.


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## bushinspector (Dec 27, 2009)

I once got into the same situation where we were repairing a haul road that ran under a overpass and the road failed. I went in and dug out some of the soft material and placed bolders in the holes and then backfilled it with two inch material. Still holding twenty years later. The road is in a gypsum mine and the 65 ton trucks are driving over the failed area at 50 mph.


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## dave c (May 6, 2010)

bushinspector said:


> I once got into the same situation where we were repairing a haul road that ran under a overpass and the road failed. I went in and dug out some of the soft material and placed bolders in the holes and then backfilled it with two inch material. Still holding twenty years later. The road is in a gypsum mine and the 65 ton trucks are driving over the failed area at 50 mph.


 

Might be worth looking into, to what depth did you dig out and how big were the boulders? The fill is about twenty feet so far first five or six feet good compacted offsite material, but then the owner insisted on using this crapy fill, funny though it seems like im the only one who is concerned.


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## Redneckpete (Feb 22, 2008)

Get the owner to sign off on your concerns, then carry on. It probably will tighten up over time, I have never yet seen soil that stays gumbo when it dries out. Still, make sure you are covered.

Pete


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## bushinspector (Dec 27, 2009)

We dug down about six to eight feet and used the 65 ton haulers to dump the bolders in. I would guess the boulders was about six tons each. Keep in mind that this was being used in a mine sitting so we was trying to build it up to handle the trucks with a full load. This area was so soft when we dug down water came to the surface.


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