vibratory roller

[Randy88]

First I've never used or been around one before, only plate compactors.

What we're doing is grain bin pads and building pads after the footings are poured we want to go in and "possibly" use clay to back fill with if it can vibrated with a sheep's foot roller instead of hauling in 100's of truck loads of crushed rock. I need a good enough base to pour cement over the top right away. What we've done in the past is haul in clean rock and plate compact it which has worked fine. But then I have to haul off all the clay and was wondering if I could somehow reuse it and save all the trucking and also "some" of the purchase of the rock and instead put that into a vibratory roller and speed this whole process up considerably.

The fill will range from 2 feet to 6 feet deep. I also have pit run uncrushed strippings available onsite as well if that would help out any. The stuff with too much mud mixed in to crush type material that was used to build driveway base out of mixed with cover crush rock mix where the old bins and buildings once stood, also have broken up concrete we thought about crushing smaller and dumping in as fill too. Not sure any of this is suitable, but thought I'd ask those that have been there tried it before.

If this idea isn't feasible, I'll have to dedicate a couple trucks to hauling in and back offsite most of a summers worth of time and two drivers and trucks.

We were thinking a smaller ride on vibratory sheep's foot that we could pick up with my crane and set inside once the footings are poured, then lift back out once done, something under say 15,000 lbs.

We've never poured concrete over anything filled that deep before that wasn't filled with clean crushed rock, everything was much shallower and we always left it sit for a few years before pouring the concrete.

 

[CM1995]

Need a little more info -

What type of clay do you have to fill with? Is it fat, lean, silty?

How does the clay react when it's wet?

What is "pit run uncrushed strippings"?

Is there a geotech involved?

Completely doable depending on your type of clay and time you want to devote to it. We fill with lean clays all the time and put large buildings on it. Crushed concrete is also a great fill material and can be mixed with your clay if it's a little on the fat side.

Ingersol Rand which is now Volvo made some nice small ride on rollers you may want to look at.

Something like this -

https://www.machinerytrader.com/lis.../1996-ingersoll-rand-sd40f-padfoot-compactors

We are about to start a new dining hall for a private school where we are going to demo the existing dining hall, crush all the concrete, block and brick then use it for fill in the new building pad. Instead of buying virgin rock at $24-25 a ton delivered we can rent a small crusher for $8K a month - win, win and the architect signed off on it.

 

[Randy88]

Not sure what you mean by fat, lean or silty clay, I don't think it would be considered silty, its partially blue clay mixed with a bright brown clay. If you leave it dry out, and can get it dry enough, even with bucket teeth you'll have a very hard time to even dig it, your more prone to scrap it off in thin layers, if its wet enough and I mean super saturated, you can pour it out like semi solid pudding. The stuff I'm dealing with is pretty much on the dryer side, since there is drain tile installed under it and in the area's where we are going to put these buildings. I even have a considerably amount of prime black topsoil to work with as well, but that we can spread out anywhere and isn't something we'd have to haul away to remove.

Pit run rock or some call it strippings, are rock and clay where the clay content is too high to bother with crushing, mixed in with rock that hasn't been crushed. We use it all the time for a base material under driveways, its all limestone based rock so it breaks up great to just dig it out of a hill [most farmers in my area have somewhere on their farms to do this] and we load it up and use it for fill in area's that no engineer is involved. To those with access to it, its basically free and it keeps the hauling cost to a minimum because its already basically on site or a couple miles from where its needed. Basically old abandoned quarries have plenty of this stuff laying around to get for free.

The concrete is old demoed building material, no rebar in it and I don't have that much of it, maybe 30-40 dump truck loads, but I thought if I'd just use a breaker on an excavator and get it smaller in size somewhat, five gallon pail size or less and spread it out as we filled and packed just to get rid of it.

I haven't tried to rent a crusher yet, doubt it would be feasible to even consider, but I do have access to a couple hundred dump truck loads of broken concrete which is a fraction of the hauling distance compared to trucking in rock.

The quarries I deal with and where I dispose of broken concrete is about 20 miles per load to haul out and bring in, so 200-300 loads adds a lot of miles just sitting behind the wheel as I see it shuffling components around.

I've also been approached by others with the same situation and asked to do that trucking as well, so this whole problem might balloon to that 800-1000 loads pretty fast if I'd even consider it............or find an alternative method, like I'm asking about.

 

[Randy88]

I forgot to mention, when we are building terraces or ponds, we ribbon the clay with a thumb, if you can ribbon it out flat about six inches or so, the moisture is right to start shaping and building, if its too dry or too wet you can't ribbon it, this type of clay ribbons really well, probably not the way you judge moisture content or clay consistency, but its seemed to work for decades in my area.

There is no engineer or geotech involved with any of this, they are not needed or required for ag buildings in my state unless your dealing with manure storage or livestock once over a certain number of animals, anything less and we're exempt. Certain sizes of grain bins do require them to be involved, especially once they are of a certain size, insurance pretty much mandates those terms though, more so than laws. All these are far below the sizes and criteria where insurance even cares so to speak.

 

[CM1995]

Just off the hip pocket I would break the concrete down to 2'x2' pieces or smaller then spread them in the closest thing you can get to a single layer. An excavator works best for this as you can lay the concrete pieces in like a puzzle and not beat yourself to death trying to blade the pieces.

Then place a 1' or so of pit screenings over the concrete and compact with vibration to fill all the voids, then fill with the clay to subgrade. I would keep the concrete rubble at least 2' below subgrade and have at least 6" of clean washed rock under the concrete slab but you already know that.

The term "fat clay" is a clay that will loose is strength when wet and shrink when dry, not exactly expansive clay but not good for building either. From what you describe your clay sounds more on the silty side due to the fact it becomes more liquid.

When we do a project where there is a geotech involved we make good money undercutting fat clay and bringing in structural fill. When we do a project with no geotech involved with fat clay we'll mix crushed stone in and work the clay until it's stable and not pumping.

The best way to test if the soil is compacted is a loaded tandem dump truck, a nuke gauge will lie with bad input but proof rolling a fill lift with a loaded tandem won't lie - just like small children, drunks and yoga pants.

 

[Randy88]

So with the padfoot compactor like one you listed, how much compaction does it do per pass, how many passes per lift does it take, how much overlap do you do on each pass, how many different directions or angles would you recommend a person have to do etc. The larger the compactor the less passes per lift I'd guess, but is there a rule of thumb to go by for each weight class of compactor, are there similar sized compactors that are better so to speak, I've been reading some can change the compaction zone on the go, somehow from horizontal to vertical compaction, is this something really needed or just another sales tool to sell machines?

 

[CM1995]

Never ran one of the new compactors with all the tech just our trench rollers and Cat 533E.

Now there is no hard and fast rule on compaction as every material is different. A general rule of thumb compacting clay is go over it until the "feet walk out" which means the pads on the drum are no longer sinking in the fill.

My suggest would be to do a test area with the clay. Put a 12-18" lift of the clay in an area large enough to make several passes with the compactor in each direction. When the feet start to walk out roll a loaded tandem dump across it and see if the soil pumps. Pumping is when the soil rolls in front or behind the tandems. Flexing is common with clay and doesn't necessarily mean it's not compacted. Normal flexing is usually between the tandems and looks similar to taking your finger and pressing a rubber ball, if the soil comes back into place with little cracking it's probably fine.

Check your work with a loaded tandem on your first couple of lifts, it's just cheap insurance.

However you can over compact dirt where it starts to break back apart then you've lost your bearing strength. More than once we've had issues with the wrong numbers in the nuke gauge and we over compacted the material only to have to do over again.

 

[Randy88]

Thanks CM for the information, I'm going to see if I can find a padfoot to rent in my area just to try one out and see how things go from there.

 

[grandpa]

Sorry to say, but I wouldn't put clay anywhere close to a concrete pad. I just finished a 500,000 bushel

grain bin site. We removed all the topsoil which was about a foot deep, then hauled in sand to grade. Compacting every scraper load of sand. Soils engineer came in, tested and we had to sub cut one area down over 5 feet and haul back in class 5 road base to bring it back up to grade compacting all the way. Each bin holds 120,000 bushel so it takes a hell of a footing. I don't know how big your going. Cm, you probably can get by with clay down there, but clay up here in country where frost can go down 7 feet or better, its a no no.

 

[CM1995]

Cm, you probably can get by with clay down there, but clay up here in country where frost can go down 7 feet or better, its a no no.

There is no probably to it...

If we didn't use clay here as fill we wouldn't have any fill to use.

 

[DGODGR]

I have a Bomag BW177-4. It's a 66" wide ride-on, single drum roller. I'm not sure what it weighs but I'd guess it's around the 15k# mark (maybe a little more). It's similar in size to an Ingersol Rand (or Volvo) SD 70 or 75. I had been advised that the -3 and older units are best due to their reliability and simplicity. I could not find one (that old) that I felt I would want to own so I bought the -4 unit from United Rentals. It has been relatively problem free for the 2-3 years I've owned it. In my experience the smaller ones take too many passes to reach required density. Another recommendation is to try to find one with a pad foot shell kit. You might find that the pad foot units (factory built pad foots, not smooth drum with shell kit) are less expensive than their smooth drum counter parts. I'm not sure why but, in my experience, there are more of them and they are much less expensive. Regardless, the convertible (smooth drum with pad foot shell kit) is a great option as on can use it on both cohesive soils (like clay), and aggregates (like sand, screened rock, road base, etc.) so it could be a real time saver for you (especially compared to walk behind plate compactors) even if you end up sticking with the screened rock fill.
I agree with a lot of what CM is saying but it seems like some important things are being missed. Please be sure to heed CM's comments when he says it's hard to make blanket recommendations because every situation is different. Soil types can vary even over short distances. In my opinion clay soils can be the most challenging to get right and the fill depths you are taking about are significant when you talk about putting a structure over it. Geotech firms are not usually required by "law" (as you put it) but rather for this exact situation they are sort of an "insurance policy" if you will. Their consult is requested to remove some of the guess work (and risk to all parties, and also to spread said risk) from the earthwork component on jobs where substandard soil performance has consequences. If this idea of yours would amount to a substantial savings (and profit for you), but you are taking somewhat of a risk, it would probably be well worth the cost of a soils study even if you paid for it out of your own pocket. On the downside they might advise you that the soil will not perform as required. While that would put your idea in the garbage it would save you the cost of dealing with the aftermath of a failure. The same firm could even test for you so that you would know exactly how many passes it would take with your specific compactor to reach a density that would perform the way you need it to. The other thing that the study would help determine is moisture content. This is the key to all compaction and one of the most difficult things to get right when dealing with clay soils. CM mentioned clay with too much moisture in it will "pump". The flip side is that clay with not enough often moisture won't reach the required density no matter how many passes one makes over it with a compactor. The challenge of clay soils is the difference between the too much and not enough water is finite. Furthermore clay soils can often be resistant to moisture distribution (as I'm sure you know uniform distribution of moisture through the soil is always best) so the mixing in of the required moisture can be difficult as well. That bring up more questions....Do you have water available? Do you have a way to handle the water (i.e. a water truck, etc.)?
As it relates to the compactor, you haven't even mentioned how big of a diameter the pad will be. Nor have you mentioned how you intend to lay out each lift of the fill. Are we talking about an area big enough that one could drop in a dozer (or whatever you are spreading the fill with) and a compactor? Or will you be craning each in and out for each lift?
As it relates to crushing the "pit run", I think it is possible to get some use-able fill from this material but that will depend upon how easy it is to separate the rock from the clay. Is the rock in the form of big chunks or is it broken up to similar or smaller pieces/particles than the clay? Is the clay in chunks or is it dry enough that it is mostly in the form of fines? Let me explain my line of questioning. Most mobile crushers are equipped with a vibrating feeder/grizzly prior to the crushing chamber (it is usually detrimental to run fines through the crushing chamber-it only serves to slow production and increase crusher wear) so , if the clay is broken into fines, and the rock is in chunks that are larger than the clay, the clay will fall through the grizzly and the rock will move on to the crushing chamber. The material that falls through the grizzly can usually be allowed to hit the main conveyor belt (which will re-introduce the material with what goes through the crusher), or it can be diverted to a "side discharge" belt where it will be stockpiled separately from the crushed material. In this case that might be ideal. If the soils engineer determines that the clay is okay to use, you may be able to let it mix back in with the crushed stone which would give you access to more fill material and handle less yardage before obtaining the required amount of fill material.
As it relates to crushing, a couple hundred loads (+/- 2,000 yards) is borderline for justifying the use of a mobile crusher (the things are heavy so don't forget to consider transportation costs). That will likely only take you a few days to crush (assuming you have a big enough trackhoe, and/or loader to keep it fed). There is a whole other conversation to be had about how to set up the crush and how much room you need, how close to the general public you might be (MSHA, dust control, noise pollution, etc., are all important things to consider). When you talk about crushing 800 to 1,000 truckloads (8k to 10k yards) that is definitely a cost effective quantity for a mobile crusher.
The last thing I'd like to mention, If you end up using the on-site clay soils for fill, there is an option that would eliminate the requirement of a crane. One could use the on-site clay to ramp up, and over, the foundation. Once the compactor, and whatever your using to spread the fill, are inside they could consume the fill material that made up the interior portion of the ramp. Once they filled their way to the top (or near the top) they could simply drive out. Even if you needed a small ramp at the end (if you left the grade down some to make the last bit up with the stone), it could easily be dug out after the machines exited under their own power.

CM: I'd love to hear more about the crusher that you can rent for $8k per month. The one I'm renting now is $8k per week ($24k per month) and that doesn't count transport, or fuel, or support equipment, etc.

 

[Randy88]

The bins we are putting up are used small bins, 24 footers and 30 footers for now, the buildings are 40x 140 and right now talking two of those, the rest of the jobs involve smaller shorter 36 foot bins with one being a 42 because he scrimped on rebar and its an old bin, and the foundation is completely shot. What we want to do is nothing fancy, but we want the bins set up off the ground more, so we're raising them above grade by 3 feet, going with a footing wall for the perimeter and then capping the entire wall tops and floor in one pour. Might be severe overkill, but I've had enough of broken pads and unload augers that require a person to dig down the truck auger you need to use to load out the bins. Also had enough of rats undermining all the old foundations and this go around we're attempting to make it much harder for them to do so. Anyhow, plenty of others are watching this ordeal unfold and they seem to like the concept and since nobody else will do it this way, [floating slabs are all the rage in my area] several have expressed interest in getting me to do a portion of the work for them as well, [again not sure it even interests me, just asking questions]. So I'd agree with what's been said so far, I'd have to disagree to a certain extent clay is not an idea base material, since almost all the bins, with the exception of the ones over 50,000 bushel are all put on whatever is onsite now, basically they just scrape off some of the topsoil and set up a form about 12-18 inches tall and rebar them and pour it as one pad and they've been doing it that way for decades in my area. Fast, cheap and easy seems to be the motto by the industry as a whole.

Last year I priced two new bins, 15,000 bushels each and the bin company didn't even want to scrape off the topsoil, just setup the forms and pour the floating pad, when I told them the area I planned to put them just had black dirt dumped in two years ago, they said, don't worry about it, by now its good to go??? I've talked to a half dozen concrete contractors and have been given the exact same answer from each, I've been told the floating slab is the tried and true method for bin pads, if your concerned, add some more rebar??

To get the material inside the foundations on the bins, with clean rock we just planned to use a crane, set a skid steer inside, then a compactor and use a cement bucket to dump the rock inside the foundation, level it off with a skid steer and pack it in place. With alternative fill, like clay or pit run rock, we'd just do the ramp technique but instead of driving over the footing [we'd have rebar sticking up out of the wall to lay over for the top cap and floor in one pour, we'd just dump it over with a crawler loader or backhoe, when done remove the ramp on the outside.

Most all of the concrete contractors I talked to used Class A road rock for fill material, one used cheap sand because he got it for free and plate compact it in place, cover it up with some better rock so that's directly under the concrete and cement over the top?? As an industry as a whole, mud, rain, you name it, anything goes it seems nobody worrys about any fill material, just use what's onsite and hope for the best is what it appears to me. So I thought I'd try a different approach this go around, far deeper into the ground, a wall with a footing under it for the outside perimeter, cap the wall and pour the pad in one pour with more than enough rebar to hold it all together, mix somewhat sorted but not crushed pit rock to sift some clay out of it, add some clean rock in to padfoot vibrate it all in place and if it would work, reuse some of the clay and broken up cement and driveway base material we have onsite now just to get rid of it and save figuring out where I'd have to go to dump it.

I don't have any of the answers, but others are also wanting to know if they could bury their old foundation material inside the new foundation, to use as fill and also get rid of it, mix in either clean rock, class A or sand and padfoot vibrate it in place, cover it up with some clean rock, rebar it and cover the whole works up with cement.

For the buildings, we'd do the same footing under the wall, four foot deep wall, build the building on the wall, dump as much stuff inside as possible rebar the floor as well and cement over the top for the floor for equipment to park on. The buildings won't have the wall and floor tied together, so those we can build the ramp up and over the walls to drive whatever we want inside to spread fill and pack with, once done the wall tops will about about six inches above the ground level outside.

 

[CM1995]

CM: I'd love to hear more about the crusher that you can rent for $8k per month. The one I'm renting now is $8k per week ($24k per month) and that doesn't count transport, or fuel, or support equipment, etc.

$7800 a - on EDIT- a month, plus mob, fuel, taxes, etc.

It's a small jaw a SMI Compact 50TJ from the Cat dealer's rental fleet. This is a small private school campus that's going to be fun getting our 321DL and 325FL in much less a larger crusher.

https://www.smicompact.com/equipment/50tj/

First go at crushing and this job will pay for the rental and the first round of OJT.

Back to the compaction question - a loaded tandem dump is still the cheapest insurance and will not lie like a nuke gauge will.

Case in point we fought this job for 3 days where the nuke was saying we were at 85-90% yet a loaded tri-axle dump with the lift axle up (85K lbs on a tandem), backing over the lift was not pumping. It took 3 proctors for the geotech to finally get the right optimum moisture. Furious was an understatement.



The pic above after we continued on with the fill lifts that were perfect under the loaded tri-axle backing over it. When the geo-tech finally got the correct moisture content the tests hit 98-100%. They went back and re-calculated the failing tests with the new numbers and we hit 98-100%.

A dump truck will not lie to you.

 

[DGODGR]

I fully understand what you are up against Randy. There are lots of ways that engineers and lawyers have found to create jobs for themselves. Most of them are things that those of who are not in the world of agriculture must deal with. My understanding is that in a "floating pad" scenario the real consideration is making sure that the base of the pad is thick enough to bridge over any imperfections of the soil and that the foundation, as a whole, has enough mass to keep the top from toppling over. If the square footage of the base is enough to reduce the weigh transfer (low psi) the supporting soils don't have to be very robust.
As it relates to the ride-on compactor those small circles might get the operator dizzy. For that size, and for the fact that you are already employing skid steers, you might want to consider Allied's skid-pac. I would describe it as a "Ho-pak" (also known as "shaker heads") attachment for your skid steer. For that matter one can also get a pad foot roller attachment but I have not heard great things about those.
CM:
I will agree with you on questioning the nuke test. We usually use a water truck as It is the heaviest truck we usually have on site (not many 85k# trucks here). I've not had nuke test issues with clay but I have with 3" ABC. I think that the problem is that one can get a few stones close together (segregation) and if there aren't enough fines in that area voids can be created. The rocks are still locked in place (so there will be no yielding or soft spots) but the nuke gauge detects the voids. The fill material is so dense that the tech has a hard time getting the spike (that makes way for the nuke test probe) through the fill yet somehow we get a failing test.
As it relates to that SMI crusher I'd love it if you would start a thread about it (or maybe discuss it in the other crushing thread that we've been engaged in). The claimed output (50 tn per hour per the specs) is only +/-33 yph but at 26k# it certainly peaks my interest. Price would be a large factor as well. I can't imagine that it's very inexpensive though at $7,800/wk rent (your previous post stated $8k per month). The crusher I'm renting weighs 75k#, rents for the same $8k/mo, yet costs $475k to buy.

 

[CM1995]

Price would be a large factor as well. I can't imagine that it's very inexpensive though at $7,800/wk rent (your previous post stated $8k per month). The crusher I'm renting weighs 75k#, rents for the same $8k/mo, yet costs $475k to buy.

Oops that was a typo. $7,800 a month plus the other stuff, I guess I had week on my mind after reading your post.

Sales price is around $200K for near new from what I've seen on MT, haven't asked my salesman about the price on this one although Thompson has a used one on MT with 217 HRS for $165K, might be the one I'm renting.
https://www.machinerytrader.com/lis...-smi-compact-50tj-crusher-aggregate-equipment

At that price and easily moved it does have a spot hence the reason we're trying it out. At this point I am not interesting in making a sellable product just reduce trucking costs and re-use materials on site. Our traffic has gotten so horrible that it gets risker and risker trying to estimate roundtrip haul times.

Sold the GC and the school on less truck traffic in and out as this is a fill site, green - reduce, re-use, recycle and the safety aspect of decreasing the truck traffic through campus.

If we can get 50 tph I'd be thrilled. Where this school is located is not close enough to use our dump so we would be taking the concrete and brick to a recycling yard that is a 1 - 1.5 hr round trip depending on traffic. There was enough $$ in trucking that the crusher rental made sense and I've been wanting to give it a try.

I'll either start a new thread or add it to my Projects thread.

 

[Randy88]

The floating slab thing, as far as I'm concerned is a joke at best, as for bridging over imperfections, that doesn't happen either. The contractor basically just scrapes off some topsoil, enough to get the height of the forms at grade and then back fills with whatever they feel like, most like gravel or sand to create the mound in the middle where the concrete can be thinner. So at most the so called foundation is only in the ground about six inches or so, ideal depth for rats to tunnel under and undermine the whole center, which causes voids and no matter how much rebar, once the cement cracks, they dig right at the crack seams and are under the aeration floor and have a beautiful highway into and out of the bin, then dig from bin to bin and before long, you don't even need to see them anymore, your entire site is undermined with rat tunnels and hundreds to thousands of rats make their new permanent homes around your buildings.

CM neat crusher, let us know how it works out for you. I can't fathom the time spent hauling anything at that rate, what do you have 20-30 dump trucks to be able to get anything done?