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R & R warehouse floor

Discussion in 'Demolition' started by oceanobob, May 14, 2016.

  1. oceanobob

    oceanobob Senior Member

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    Existing 5000 sf warehouse floor to be removed and replaced. Floor is concrete over wood. Wood framing similar in concept to a raised floor house with 2x joists, cripple walls in most of it, although wood girders in one section. Has perimeter concrete foundation and interior grade beams; both short stem wall shape. Due to vintage, flooring sheathing is two layers of 1x. No plywood. A wire mesh reinforced concrete was placed directly on the wood. We figure concrete to be about 50 yrs ago, give or take. Wood is dry rotted and many repairs conducted over the years. This 'repair' is to remove everything and fill, then place a new concrete floor. Initial actions were to brace the roof and walls in sequence and replace the oortion of the perimeter walls to the floor elevation with either grouted CMU or cast in place concrete. Then cut through the dock to gain access to the inside and remove the old materials. Trials were conducted on the concrete removal process: sawing it to make squares and pulling it up with a quick bolt/chain/etc accomplishes the separation although the sheathing sticks to the concrete. Sending the concrete to the recycle with this amount of wood is a no no, so the decision to cobble the concrete squares by working the hammer atop the existing slab achieves quite a bit of separation, and the cobbles sent to the bottom of the approximate 5 foot fill for "permanent storage". The wood removal goes equally slow as it is so rotted it falls apart mostly but occasionally there are members which require sawzall etc. Walking on the sheathing after a square cube of concrete is removed will get you a leg down and maybe a rusty nail bite LOL. The wood gets smashed up and dismantled with the reachlift, then hauled out with the forklifts and bins to go into the rolloff containers. Some of the above is shown in pics. Seems the overall process has become concrete removal & cobble, then the wood removed to make a hole to place the concrete. Process is sort of iterative in lieu of sequenced. One bay is almost done in the pics. For those of you who work in soil with cobbles, maybe a comment please. I could speed up the process by concentrating efforts on removing all the concrete, rubble it, then place & mix it in lifts in the one section that is completed that you see in the pics (dump truck hauls the fill inside and the skip spreads it, reachlift and skip wheel roll is compaction on this lift and the sheepsfoot ride on compactor will be next (just to make sure and get the edges better) prior to any more fill (am about 15" filled of rubble and soil, just enough to cover the interior grade beams & rubble so we could drive the reachlift and dumptruck). The fill is inert (minimal clay) sandy loam, mostly sand. Fill is pre-conditioned with moisture prior to hauling it into the building.

    My Question: Unsuredness is holding me from bringing the concrete rubble 'too high in the fill' - but if I could mix all the concrete in this one bay/section, then I could attack the balance of the wood all at once with a midi ex and a thumb then hire a crew for a couple days to load the roll offs with that wood. Then I could 'get after it' for the balance of the fill and the new 6" slab. Any suggestions on getting good compactible subgrade with these cobbles? Size ranges from less than a square foot to a few at 18 by 12 by 4 thick with one or two at 18 by 18 by 4 thick. Would you fear having a compaction job with mixed materials? I would hazard a guess and say it will take about 3 feet of mixed fill (ie sand w cobbles) depending on the ratio to get a home for the concrete in this first bay. That would give me 18" of sandy material with no cobbles and 6" or so of Cl II base under the slab. Never worked much with mixed fill as am usually in pure sandbox style soil where we remove, moisture condition, and replace. Regarding how to deal with cobbles - does 'engineering opinion' allow these cobbles "back in the ditch/fill" or are they always to be screened away? We simply can not take this concrete to the recycle since there is just enough wood stuck to it to make it rejectable but not enough wood to allow it for fill due to organic less then 2%. There are no pipes or conduits, only the fill with the concrete atop. P4261837.jpg P4271843.jpg P4271847.jpg P5041897.jpg P5131992.jpg
     
  2. CM1995

    CM1995 Super Moderator

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    Bob you've got an interesting project to say the least. I haven't run across something constructed in that manner, it's a wonder it held up so long with warehouse traffic.

    We encounter rock fills on our jobs from time to time. One was a 20' deep fill with shot rock. The artic trucks dumped at the proceeding fill lift and we pushed it off with a D6. The larger pieces went to the face and the fines covered the preceding lift. This fills the voids around the larger pieces of rock and levels out the lift. You'll need to do something similar but a different approach.

    So you will have 2' of engineered cover with 18" of sand and 6" of base?

    The key to reduce settling around the concrete fill, especially the large concrete pieces, is to lay the largest pieces out flat on the very bottom of the lift. Leave adequate space around the pieces to fill in with your sandy material. You may have to lay the large pieces out, fill in the voids around them with sand and then a layer of smaller broken concrete.

    What you don't want is the large pieces piled in one spot on top of each other in a manner that creates voids, over time the sand fill will work it's way into these voids and cause settlement. 18" of cover to sub-base is the minimum I would go over the concrete fill. I'd pay special attention to the first lift of sand over the concrete and make sure the sand is vibrated throughly in order to fill in all voids.
     
  3. oceanobob

    oceanobob Senior Member

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    Appreciate the suggestions. If you look at the pic with old wood coming up, "peek" beyond the wood, there is a temporary rubble pile that 'had to go somewhere'. That wood in that pic is now gone and I will spread that rubble out with the mini before the next lift ... I knew that type of rubble pile covered with sand fill wouldn't be good at all. Gives an idea of the size of the pieces.
     
  4. movindirt

    movindirt Senior Member

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    That's a interesting project for sure! I see you've got a skid bucket chained to the folks on your tele, did the same thing a few days ago to backfill around a pool. I would think so long as the concrete is in small enough pieces that the sand can flow around it should be fine to bury it.
     
  5. oceanobob

    oceanobob Senior Member

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    Since you mentioned the [two] chains on the accessory bucket for the reachfork..... that bucket has these two pockets for the forks to slide into and on the heel are these ears with a hole; a pin traps the fork into the bucket : NOT! The bucket is so loose on the pockets that the fork becomes dislodged from the bucket (jumps over the pin) and so to add assurance it won't fall off the machine we dreamed up those chains with some shackles (to R/R) around the carriage bar. Aside from that, this bucket comes in quite handy. I initially thought I wanted a wider one, but that makes the overall turning clearance bigger and the reachlift is already long. Bucket setup is not suggested for excavating but it handles loose materials well.
    *
    *
    Thanks for the comments on the fill with and over the concrete chunks-cobbles. One person (my helper) suggested:
    ```after we place a lift 12 to 15" of combined fill material (ie cobbles with sand placed over and coincidentally wheel rolled due to direction/method of placement) then
    ```use the excavator bucket to loosen or till/agitate the material [I imagine many short strokes similar to tilling up a garden - not long plowing action but it prolly is the same effect]
    ```put a little more water to it,
    ```then compact that lift with the ride on vibrating sheepsfoot.

    I asked him why he thought that was better and he said he didn't really know but that is what idea came into his mind. He is a good compactor operator, always achieves good numbers, drives the machine calmly, etc.


    As to placing the unbroken square sections (like pieces of a sidewalk) shaped concrete:
    1) I feel that random chunks (because they are simply smaller is a bit better) and the time to break up those sawn sections into cobbles/rubble is pretty quick.
    2) And I would offer that handling the concrete material will take less time by first processing it (busting it a bit) and filling many chunks it into a bucket to spread around as opposed to setting one squarish slab at a time like a checkerboard - as that could also be a pita. LOL Pita means 'Patience Is The Answer' as in a trial of one's patience, not the colloquial acronym.
     
  6. oceanobob

    oceanobob Senior Member

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    Some more pics showing one bay filled with a layer of cobbles and the fill just above those rows of foundation grade beams, and half the center bay similarly to the above mentioned bay but with another layer of spaced cobbles ready to receive their layer of fill/cover. The cobbles are spread carefully with a machine and moved &/or located by hand to assure there are "no stacks". Then the pre-moistened soil is thinly added to just cover the cobbles with a couple inches and then some more water added* then credit taken for the loader wheel roll, then the compactor and it in two directions if possible. The time to further break into cobbles the saw cut out slab pieces isn't much and it seems better to accomplish this project using only cobbles as opposed to those larger saw cut pieces: also they are slow to handle for the placement.
    *Sandy soils tolerate the over water as opposed to the clay soils so this factor was added into the recipe, figured the wetter sand would move or mold around the cobbles more readily.
    We are looking ahead to locate a Z boom concrete pump as it may be able to open/unfold inside the room. The larger boom pump beats dragging a co concrete hose and allows for a mix design with more 3/4" aggregate. Larger aggregate helps with the shrinkage cracks. Sadly, concrete in fact cracks but we keep it to a minimum by using certain types of dowels that allow horizontal movement but not vertical, and a rebar mat centered in the slab.
    P5192025.jpg P5192026.jpg
     
  7. ScottAR

    ScottAR Senior Member

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    Hard to tell about access (I see some columns to work around) but a concrete conveyor might be able to boom into there.
    I understand they have no restrictions on aggregate size. Unique project for certain. Remember there is profit in unique. ;)

    Just an idea...
     
  8. oceanobob

    oceanobob Senior Member

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    We have heard the use of a telebelt (which is what they call a truck mounted conveyor belt(s) that has a frame that can extend retract) will be worthy of investigation.
    *
    As to unique, fyi the building was originally carpentered in 1940, possibly 1937. Likely some of this portion was one of the additions - let's say 1945. All 2" thick wood: 12" section on floor and 8" on walls; tongue and groove both sides of the walls....etc etc. Built with no electric saws, no skilsaws, no sawzalls, no drills, no impact guns, no manlifts, no forklifts...just handsaws & hammers and a nail pouch. No wonder my grandfather [a carpenter and a brick mason] gave me advice on not to take a career or job in construction. Am glad to be the one to give this old structure a new floor.
     
  9. CM1995

    CM1995 Super Moderator

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    Looking good Bob. I don't think there will be an issue with settlement of the new floor.

    No doubt on the old school carpenters. My grandfather and father were both carpenters back when a skill saw was a revolutionary tool.
     
  10. oceanobob

    oceanobob Senior Member

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    We made it to the end of the removal of the floor. There's a couple details for some hammer work, but the wood is all but gone.

    Using the reachlift has helped spread just an appropriate enough fill material (sandy soil) to cover the cobbles and it gets really wetted to 'flood it in' then track roll and kneed w bucket to help assure no voids. The layer of cobbles and followed by the skip loader was placing a bit too much cover.

    Still researching how to get the boom pump thru that door....

    Now a few more cobbles to place and then "fill baby, fill". P5242050.jpg P5242054.jpg P5242057.jpg
     
  11. ScottAR

    ScottAR Senior Member

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    Last edited: May 26, 2016
  12. oceanobob

    oceanobob Senior Member

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    Getting it filled in. Subgrade work. Then a layer of class II base under the concrete slab.

    As to the concrete and the placing method, there are three bays and we knew we wouldn't do it all at once and thought maybe one then the other two but have decided to do the initial bay against the wall by "hose dragging" as there is no exterior door in line, it is also the shortest bay. We are going to get that one in first. P5302087.jpg
     
  13. CM1995

    CM1995 Super Moderator

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    Project is coming along nicely Bob.
     
  14. oceanobob

    oceanobob Senior Member

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    Pic of our 1000#, single cylinder, diesel of course!, Hand Crank Start plate compactor finishing off the marks from the padfoot and smoothing the top of the subgrade prior to the road base.

    P5312089.jpg P5312088.jpg

    The guy who sold me this didn't put a throttle cable up to the handle as he used a small vise grip to hold the throttle lever in the run position. One fine time, he started it and it lit off quick so quick that he didn't pull the crank start handle so the thing was spinning wildly off the racing engine and the compactor was jumping/dancing all over ... it was full of fuel and he couldn't wait till it ran out so he carefully? reached over & around the spinning crank, released the vise grip but they sprang from his clutches and fell just in time for the handle to come around and launch the pliers onto the side of his face / cheek. It looked like he walked into a pipe or similar type of injury. Yes we have a remote throttle via cable.

    And it is a Beast to drive around but I like it cause it is diesel and it hits the ground brutally.
     
  15. oceanobob

    oceanobob Senior Member

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    Got the base to grade and some forms. Still a ways to go on the fill on the final portion. P6022096.jpg P6022097.jpg P6022098.jpg
     
    Last edited: Jun 3, 2016
  16. hvy 1ton

    hvy 1ton Senior Member

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    Would a tele-belt truck work? That's a cool little single drum. How wide is it?
     
  17. oceanobob

    oceanobob Senior Member

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    The other day we had the one section up to final grade and road based, and yesterday's long day we succeeded in mortally wounding the premoistened soil in the stockpile. Took some pics last nite of the final section almost filled 'cept for the haul ramp and the dock.

    Single drum compactor has a Deutz air cooled, mfg by Dynapac, is a CA12PD (not a current model) with a drum of about 4' in width.

    Also some fyi concrete slab details: notice no rebar laps 'inadvertently' in the saw cut (crack control) joints nor any bars skewing aiong said cut line(s). also notice on the construction joint (ie 2x6 form board facing the next slab) there are the diamond dowel pocket formers where a plate dowel will be inserted once the form is removed. Dowels to the perimeter wall are smooth & square section. Slab is a full 6" thick. Stakes in center are the clips we set for the skreed rails and skreed rods. This concrete will be placed, potato head vibrated, hand rodded in lieu of vibrating skreed just because the issues with the pipe rails for the vibrator with all the columns & walls. IMO Never achieved decent flatness with a "wet screed" vibrating skreed, we always run it on pipes; the slump will be kept to a 4" which the vibrating wet screed is also another challenge for it.

    Finish will be channel floated and panned, and walkbehind trowelled (no rider which really helps w flatness but is a bit of a chore to handle).

    Mix design is .53 w/c ratio with 5 3/4 sacks cementitious [which is the word used to address Summation Of Portland Cement and Flyash content], fyi this has around 10% flyash. The aggregate is a blend mix adjusted to trailer pumping via a 3" hose. and mix water is certainly being replaced with medium and high range water reducers, also there is no air entrainer. Regional geographic aggregate is a fairly significant contribution to concrete shrinkage compared to data we have seen in other parts of US thusly rebar for temperature and shrinkage as well as seismic considerations. Likely will be accelerators* (and/or additional cement content) due to the inside placing conditions where it is cooler not to mention we are coastal weather which some days can be get as high as 68 to 72 F.

    *Want to allow slab for forklift operation at 3000 psi w/i a week or so of placing. Owner suggested we should consider fibers too....maybe we will, but they increase water demand.

    P6042099.jpg P6042101.jpg P6042102.jpg P6042103.jpg P6042104.jpg
     
  18. Jim D

    Jim D Senior Member

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    oceanobob, good work!

    A long time ago, I worked on a job like that one. The engineers designed an under slab fill using rigid foam; geo foam. Truckloads of 2' x 4' x 10' foam slabs. It was really easy to put in place. They pored the concrete slab warehouse floor on top of styrofoam! (The concrete contractor used a laser screed and no forms or screed boards, it was very quick, and it came out very flat!)
     
    Last edited: Jun 8, 2016
  19. oceanobob

    oceanobob Senior Member

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    We have no laser skreed operations in our area. We cajole them to travel here when the jobs are at least 10 to 15k SF.

    The one bay that had to be done with a hose pump (no hope of a boom or other contrivance due to no door access) was completed yesterday. We selected a mix that had almost 1800# of rock (not counting sand) and kept the cement to 5.5 and lessened the water with chemicals, also added a small dose of accelerator. The hose made the job slow, that was apparent right away so we 'stepped out of the line at the batch plant' on the final truck. Because we went early, there wasn't a major consequence with that last minute adjustment.

    The last truckload we added some more cement and some big fibers and a little more accelerator as that truckload is a pathway to another part of the warehouse (help occupants gain access asap).

    The slab was vibrated, handrodded with aluminum skreed rods, carefully floated and holes filled, then observed: there was little bleedwater so we knew we had reduced quite a bit of the water; film was added to protect the surface although our humidity was around 60% and no direct sun. Panning and channel floated reiterations once it could be walked on, then machine finished and film curing compound applied. 9 hours and the rest of the cure application had to wait until we could walk on it w/o boot marks at hour 11. Clearly the room low temps don't help setting.

    At the construction (cold) joint, edging was not performed as this usually 'rolls the flatness away', instead the plan is for the next bay gets bumped against this one and the butt joint gets a saw pass to clean up the appearance and the sealant/low modulus epoxy added.

    For the equipment folks: I have worked with this 'one man and a helper' concrete pumper, he maintains his equipment and it is reliable. His hourly rate is 'above market'. Not knowing too much about the pump mechanism, but over the years we have endured clogs and stoppages with other companies so I stay with this outfit. The finishers don't pay this rate and they don't typically push the rock content since all concrete is the same? When they learned the rate, they were cantankerous (pls recall I was paying it) so I asked them "Do you like Clogs/Stoppages/Beating Hose with mallets etc etc." They quieted up, but value is a difficult concept sometimes.
     
    Last edited: Jun 9, 2016
  20. oceanobob

    oceanobob Senior Member

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    Compactor makes final exodus and wet saw cutting crack control joints. P6092115.jpg P6092117.jpg