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what would it take to demo these foundations...

Aliate

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Seattle, WA
I was asked to bid on this and it would be my first foundation demo so I was curious what it would take to get these things gone. There are 12 of them and I was just going to over estimate and figure 1 container per unit. I thought I might be able to just get under them with a 160 sized machine but upon further inspection it looks like it may take more than that to break these things up.

Any suggestions/advice?

IMG_20140819_093401_944.jpgIMG_20140819_093419_222.jpg
 

CM1995

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That could be somewhat easy with a bigger hoe and then it could be a big PITA. Do you know the size of the footings? If those stem walls turn out to be heavily reinforced with L dowels into a large footing it could turn into a nightmare if you didn't have a hammer.

I would plan on a 320 sized machine. If the walls and footings can be dug out, then you can use the poor man's hammer trick and break them up by dropping them on one another. Might have to cut some of the rebar that will still be holding the pieces together with a rescue saw but it's faster and cheaper than a hammer. In my experience, if you can pick the large pieces of concrete up and drop them on another chunk they'll break easily. You don't have to lift them high and have shrapnel flying, a few feet works with repetition. If they don't come out with a 320 or larger hoe, then a hammer is your option to break them up.

What are you defining as a unit? I would take some measurements of the walls and get a CY number. Redi-mix trucks on average haul 8-9 yards of wet mud, you're not going to get more than that in a 20 yard can as it's weight not volume with concrete demo. The footings will be harder to estimate unless you have the drawings or info on how they were built. For example, I figure 5 CY of existing 4" concrete paving as one tandem dump load. Just from the pics, I would say one stem wall and footing would fill a 20 CY can, not including the demising wall in between and even then I might be underestimating it.

It's hard to give good advice without being able to walk the site.
 

Landclearer

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CM sounds like he is dead on. I also think one wall would fill a 20 yd can.

I would go to the site with at least a shovel and dig down and see if I could find the footer and see how wide and thick they are. Little investigating could save a lot of trouble later.

One other thing I have done in the past is dig along wall/ footer for about 6 or 8 feet than pull the end into your hole. The remaining dirt will make a hinge for a breaking point.
 

CM1995

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One other thing I have done in the past is dig along wall/ footer for about 6 or 8 feet than pull the end into your hole. The remaining dirt will make a hinge for a breaking point.

Very good advice as I was thinking with the estimators hat on instead of the operators.:D

If you dig out around the footings a rather large chunk of concrete can be removed easier as Landclearer said. On a recent small demo job we did, had a 4x6 concrete landing for a door leading out of the medical clinic. What complicated things was it was recessed 4" or so to the door threshold, around the CMU facade that clad the bottom 3' of the building. Not knowing if it was doweled into the slab or not we dug on all 3 sides of it below the bottom of the slab. A little lift on an edge determined that it wasn't doweled into the slab and came out easily. I had bid the job with time to use manual labor to chip out the concrete and cut the dowels - if they were there.;)

The GC put the risk on me if there were dowels and there were none. Sometimes you win one.:)
 

Aliate

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Seattle, WA
Thanks for the advice guys, I will be calling the company tomorrow to ask about plans and I will probably take a trip down there with a shovel, I figure a week with the right size machine is enough time or am I wrong? I'm just trying to leave myself some room for error.
 

brianbulldozer

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This may sound kind of old school, but a wrecking ball will do wonders on the vertical walls. I have a pear shaped ball (maybe around 1500 lbs., don't know for sure) attached to about 6' of heavy anchor chain. Other end of the chain is attached to the center of a piece of 6" pipe about 5' long. Grab the pipe with the bucket & thumb and start swinging. After a dozen swings or so the concrete starts to crumble out of pure fear. Never tried it on anything really heavy, but it does surprisingly well on 8" walls with single rebar mat. Only takes a second to pick up or drop the ball when you want to dig as opposed to switching over to breaker.
 

Aliate

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Brian where exactly are you located? This is in Tacoma..

Anyway, I went back this morning and did a little digging. The footers look to be 16 in wide and 6 in thick. After doing some measurements, I came up with about 720 linear feet of walls. After further calculation, I came up with 92.6 cu/yd of material including footers, not including all of the footing drain pipe Im going to have to get rid of. I am renting the equipment I would need for this job and that would include a 25t zero swing machine and a breaker if I get into trouble. I am figuring 1 week to get this done, and just hire maybe 1 or 2 roll off trucks, Im guessing it should take about 20 containers or so. Does this all sound about right?
 

Landclearer

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Aliate, I am surprised by how small the footers are but that is good news for you. A 25 ton machine should have no trouble breaking the walls and footer into pieces. I would suggest removing them all and piling them up then get 2 trucks for a day depending on travel time. Do you have any concrete recycle yards nearby. The guys around here will pay a few bucks a ton for it and that helps out on trucking.
 

CM1995

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Same here on the size of the footings, surprising their that small. 25ton ex as Landclearer said will do the job, probably won't need a hammer just use the poor mans method above if the footings are consistent. The walls and footings will break up.

If there's 100 CY of poured in place, I would plan on 25 - 20's just to be safe. No comment on the recycle yards, we have just one and they charge by the load, most of the concrete goes to inert dumps. I'm in the land of limestone, crushed stone is cheap.
 

David427

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The proper tool to use for this job would be an excavator mounted concrete densifer/crusher/pulverizer. They make short work of concrete foundations, most have built in cutters for rebar and as the name suggests they densify the concrete for max loads. Rent one.

A link for example - http://www.bodinemfg.com/concretepulverizer.html

Containers? Munch the concrete up on the first day and load it into triaxles on the second. I used to use wrecking balls mounted on lattice boom cranes back when it was still a viable method. Too slow and too much stress on the excavator.

I know things vary great from region to region but crushed concrete has been a DOT approved road base around here since the 1980's. You pay the recyclers to dump a load and you pay them to put a load of road base on your truck, quite the racket. Unless it's rebar heavy crushing concrete is candy all day long.

I can send you my address for my royalty check later.

Same here on the size of the footings, surprising their that small. 25ton ex as Landclearer said will do the job, probably won't need a hammer just use the poor mans method above if the footings are consistent. The walls and footings will break up.

If there's 100 CY of poured in place, I would plan on 25 - 20's just to be safe. No comment on the recycle yards, we have just one and they charge by the load, most of the concrete goes to inert dumps. I'm in the land of limestone, crushed stone is cheap.
 

CM1995

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I can send you my address for my royalty check later.

Don't bother, the check won't cover the postage.:cool:

If this project were in my area I wouldn't waste time with a pulverizer if the footings were that small. Pull them out with the 321, break them into manageable pieces and load out on 20's - done.

As you said David427, things vary greatly region to region.:cool2
 

Landclearer

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I agree with CM. No sense in using a pulverizer on something that small. I would rather cleanup 100 pieces of concrete instead of a million;)

The recycle yards around here cannot get enough concrete. We pay about $30 a ton for limestone base delivered and you buy a lot of water sometimes than you fight it to get it dried out.
 

David427

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I know from experience in 'Bama you guys like to take your time and use them there git er done old school methods. On the East and West Coast, not so much, time is money. But hey, where is the fun in using a rental machine unless you can beat the snot out of it. :D

The correct tool for the job, a concrete densifier, the incorrect tool, beating on it/prying on it with an excavator.

One constant in all regions is they have their big leagues and their little leagues. I was introduced to the wonder of a concrete densifier mounted on a Komatsu PC750, it munched up a failed subdivision of townhouses that never got pass the foundation stage, the city seized the property and built a school on it. It was a little overkill, the person who brought it in was getting a skim from the demo contractor but it took 2 days to munch 20 townhouse foundations. After you include the mob/demob costs it was probably a wash but a few days were saved and the subgrade was done way ahead of schedule. All the concrete was crushed onsite by a tracked crusher and used as site fill. Time = Money = EMC2 :D

Don't bother, the check won't cover the postage.:cool:

If this project were in my area I wouldn't waste time with a pulverizer if the footings were that small. Pull them out with the 321, break them into manageable pieces and load out on 20's - done.

As you said David427, things vary greatly region to region.:cool2
 

CM1995

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I know from experience in 'Bama you guys like to take your time and use them there git er done old school methods. On the East and West Coast, not so much, time is money. But hey, where is the fun in using a rental machine unless you can beat the snot out of it. :D

The correct tool for the job, a concrete densifier, the incorrect tool, beating on it/prying on it with an excavator.

First of all you don't know me or how I operate my business, assumptions are well assumptions.:rolleyes:

Old school methods make money. This is a straight forward project and I would do it exactly as I said. I own a 321 and I don't abuse it - wouldn't have to. Those large chunks will break up easily to load into 20 yard cans - read my method posted above.

There would be no reason to beat or pry on those foundations if the footings are the size Aliate stated.
 

David427

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Maybe you might want to break open the piggy bank and buy some of those new fangled work tools for the Ol' Gal?

Why jockey around 20yd cans when you can use a densifier to make piles you can back ten wheelers to and max legal load them? One day munching, one day loading - git er done!

Ya know, I hate to sound silly cause I don't want to assume anything but have you actually ever used a concrete densifier?
 
Last edited:

oceanobob

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This job looks like it is on a slope, perhaps this distinction may affect the type of machine to be recommended?
Cant tell if the materials have to be drug uphill and loaded or can be pushed downward and loaded. This may also affect the size of the machine that can be sent to the job.
I can see some straps for holddowns: I would suggest there is plenty of rebar in those stem walls and footings.
 

td25c

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This may sound kind of old school, but a wrecking ball will do wonders on the vertical walls. I have a pear shaped ball (maybe around 1500 lbs., don't know for sure) attached to about 6' of heavy anchor chain. Other end of the chain is attached to the center of a piece of 6" pipe about 5' long. Grab the pipe with the bucket & thumb and start swinging. After a dozen swings or so the concrete starts to crumble out of pure fear. Never tried it on anything really heavy, but it does surprisingly well on 8" walls with single rebar mat. Only takes a second to pick up or drop the ball when you want to dig as opposed to switching over to breaker.

Totally agree Brian . There is a good reason they call it a " Wrecking Ball ";)

When in doubt , old school get's it done . :)
 

Landclearer

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We own a Cat universal processor with pulverizer jaws and I still would not bring it in on that job. I guess we are not in the "big leagues". I think it would be ridiculous to pulverize those walls then have to clean up all that broken concrete the whole time mixing dirt in it. We have been in business for well over 20 years and have never broken a boom, stick or dented in a bucket so I guess you can tear out concrete and not " beat the snot" out of a machine.
 

CM1995

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Maybe you might want to break open the piggy bank and buy some of those new fangled work tools for the Ol' Gal?

Once again why? There is no reason to complicate this job with "new fangled work tools" as you call them. A 25 ton hoe will take care of this project with the size of the footings. Concrete performs great in compression, very weak in tension.:cool2

Why jockey around 20yd cans when you can use a densifier to make piles you can back ten wheelers to and max legal load them? One day munching, one day loading - git er done!

Depends on the job, accessibility, location to disposal site, etc. My first choice is 20's, as one truck can service two or three cans depending on haul distance, add another roll off if the haul distance is greater. No time wasted loading dumps as you can always have a loaded can waiting on the roll off. However, it depends on the individual site. Hauled a lot of concrete in tandems and tri-axles as well.

Ya know, I hate to sound silly cause I don't want to assume anything but have you actually ever used a concrete densifier?

I demo'd one several years back, for the price and the fact I didn't see the benefit of the attachment for the types of demo I perform, decided against purchasing one. We do residential and light commercial demo, no industrial or heavier structures as I primarily do site construction.

Anytime one can remove large sections of concrete and load them out it's always faster and cheaper to do it that way. That's why I didn't see the benefit of the pulverizer. The project I demo'd it on involved removing 6" concrete pavement and a small retaining wall. I had the slabs up and loaded out while the pulverizer was munching, leaving further debris to clean up. They have their place no doubt but not for what I do or for the project Aliate is bidding.

Reminds of a job we did 6 years ago for a fast casual restaurant. The existing building was demo'd to the outside walls, slab and roof because if they took the entire structure down, the set backs wouldn't be grandfathered in and the building would have set farther from the HWY. They originally planned on keeping the building slab but decided early on that it wouldn't be feasible with all the new plumbing and electrical underground that was needed, plus the fact the finish floor was going to be the polished concrete slab. The slab was around 2K sf.

I knew how the GC expected it to be done and I bid it that way - with jackhammers and a lot of manual labor. The super was worried this CO was going to affect the schedule, I told him don't worry we'll have it done in a day. In which he said - "No way".

Showed up that morning and the first thing we did was strip the sheathing and remove the studs on an outside wall in order to get an 8' opening. The building was trussed front to back with columns in the middle, so the side walls were non-load bearing. Had a slab saw come in and cut the floor into 4x4 pieces. Put the mini-ex inside taking the slabs up and ol' Blue (Gradall 536) with the boom shot through the hole. Loaded the slabs onto the forks and then loaded them into a tri-axle with high lift gate. Finished the job in the early afternoon and the super was shocked.;)

I bid the job with jackhammers and laborers as that's the price they were expecting, however I knew how to do it otherwise. In the end everyone was happy, bank account a little fatter and the schedule stayed on track.
 

CM1995

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We own a Cat universal processor with pulverizer jaws and I still would not bring it in on that job. I guess we are not in the "big leagues". I think it would be ridiculous to pulverize those walls then have to clean up all that broken concrete the whole time mixing dirt in it. We have been in business for well over 20 years and have never broken a boom, stick or dented in a bucket so I guess you can tear out concrete and not " beat the snot" out of a machine.

Well said Landclearer.:thumbsup
 
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