Concrete garage floor repair

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Old 12-10-13, 02:59 PM
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Concrete garage floor repair

About 10 years ago, a tree fell on the right side of 2 car garage and a lot of heavy rainwater flooded in. Ever since then the right side of the two car pad has been sinking. It is now down 3-6 inches on the right foundation wall and now stopped. The wall is not sinking, only the right side of pad.
Can I cement over this lowered area and level it out? Or do I have to tear up and remove old concrete pad in its entirety or just half?
Is it possible to cement over a concert pad? To raise it and level it out..?
Thanks
 
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Old 12-10-13, 03:50 PM
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No way is it sinking that much from just some water on the floor.
Something would have to be going on under that floor to be able to sag that much.
May be able to have it mud jacked. Google it.
 
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Old 12-11-13, 05:04 AM
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How long has it been in the settled position? If it's been that way for several years and has not changed, and no other effect can be seen, then I'd say go ahead. The patch may not last for a long time and will eventually crumble and crack.

Another solution is just take out the old stuff in the sunken section and replace it with new concrete. In so doing you'll find out what happened. I suspect you'll find a void in the sunken area because of the fallen tree. Perhaps a large root of the tree got disturbed or rotted out causing a void for the concrete to settle.
 
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Old 12-11-13, 05:11 AM
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so ' ever since then the right side of the two car pad has been sinking ' would cause most to think water is, at least, part of the reason,,, i suspect the wtr's continuing to cause trouble by washing out the base ( ' scour ' ) upon which your sinking floor sits.

but, to answer your specific questions:
1 - ' Can I cement over this lowered area and level it out ? ' yes;
2 - ' do I have to tear up and remove old concrete pad in its entirety or just half? ' either - your choice
3 - ' Is it possible to cement over a concert pad? To raise it and level it out..? ' yes

addl comment - would any of the above be successful ? i suspect not in anyone's lifetime,,, i suggest your post offers clues to the correct solution but that's just me,,, personally, i'd want to correct the ' scour ' issue prior to mud-jacking OR any other repr method selected
 
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Old 12-11-13, 08:30 PM
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I'd suggest using a concrete overlay to raise the sunken portion of the garage floor. Going with a "crack-and-seat" treatment of the settled concrete first will minimize the likelihood of future settlement. Also, the junction where new concrete ties into existing should be sawcut, and at least 3/4" of the existing removed to avoid a feather-edge situation. New concrete will adhere better if the existing surface is roughened, or at least made reasonably clean, before overlay placement.
 
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Old 12-13-13, 05:59 AM
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conc overlay to level floor's possible however 1st the cause of sinking must be address'd or you just add more static/dead load,,, ' crk 'n' seat ' is generally used for hgwy overlays,,, just how much seating weight could 1 apply,,, vib plate compactor isn't sufficient imo,,, last spec i saw was 50T vibratory load for 8" conc roadway & lanes were crk'd every 2' via drophammer.

where new concrete abuts old WILL be a jnt no matter how 1 tries to disguise it,,, o'lay will be bonded OR unbonded,,, bonded works best if using polymer-modified mtls,,, fastest resurfacing is either conc scarifier or scabbler,,, just my $.03 - ymmv
 
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Old 12-13-13, 02:49 PM
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Thanks joe...it took a number of years to settle..the tree hit during downburst and I noticed all water leaving br way of the crack where pad meets wall. Must have undermined it there..any ideas thanks
 
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Old 12-13-13, 02:54 PM
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Right on Norm..your thinking is top notch. Yes the was undermining by the water, it appears to have stopped sinking. Will a top over of concrete adhere? Do I have to bust out the lowered section-approx I/2 of 2 car pad?
If I could cement over the whole pad is that an option..with one side being about 1 inch thick and the other. Varying up from 3-5 inches in depth.
 
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Old 12-13-13, 02:57 PM
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Great advice..what is the minimum thickness of overlay that will stick? If I cut out by the wall and fill with concrete is that ok? Would I use regular concrete for the resurfacing? I really do appreciate your time and comments..thank you
 
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Old 12-13-13, 03:02 PM
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Yes, I feel the scour is an issue I will investigate..I believe most was wash out, and maybe some rotted roots..it is all localized to the side.

Maybe it is time to explain myself..we don't use the garage for parking..very rarely...was trying to cheap out by pouring concrete over and checking the scour at the wall edge..filling if necessary and then concreting over..worried that concrete would stick well to underlying pad if less than I inch or one inch thick..thank you for your comments and thoughts
 
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Old 12-13-13, 03:08 PM
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Does anyone know if I can post a picture here and how to. Your recommendations are all very much appreciated. Thank you all
 
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Old 12-13-13, 03:13 PM
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Old 12-13-13, 04:07 PM
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For starters, we could provide more pertinent suggestions if you would post a few pix of what the existing, settled floor looks like. Nothing too close-up, but just overall views showing the extent of cracking and settlement.

If you are considering a concrete overlay, you can use typical residential concrete, preferably with no aggregate larger than 3/4". Contrary to what others have said, no polymers are needed for bonding, provided proper surface prep work is done. I would use a neat (meaning no other additives, other than water) Portland cement slurry for bonding, brushed on the damp parent concrete just before new concrete is placed. Minimum thickness for bridge overlays that I was involved with (first one placed in 1971, hundreds more in following years) was 1", although 2" is optimum. There's nothing that says you couldn't go thinner in your lightly-loaded situation, provided you cut back on the rock size from the aforementioned 3/4"--it's almost impossible to float and finish the surface when rocks are poking through and rolling. If you are only doing a very small area, you could use a pre-packaged bagged mix from your local big box store. If your area is half the area of a double garage, the volume (about 2 C.Y.) would mandate ordering ready-mix. Hand-batching, placing and finishing many bags of Sakrete or Quikrete will result in cold joints, with the potential for failure of the overlay.

To clarify my earlier reference to "crack-and-seat" the existing settled concrete floor, I meant to just whack any hollow-sounding areas vigorously with a 10-lb. maul to break up the surface into smaller chunks, allowing each to drop down on top of the undermined base below it. If most of subgrade voids are eliminated, it's far more likely that an overlay will perform better (and not settle again).
 
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Old 12-14-13, 03:17 AM
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if someone's in a forum askin' basic stuff, i should remember tech stuff's not the best response next we'll be suggesting micro-silica overlays

ok, IF you want ' cheap out ' yet a serviceable floor for the next owner's mortgaging inspection/approval, remove the broken stuff, fill w/mtl prev sugg by bridge, & place new 4" conc on a well-compacted base,,, no more whack-a-rock,,, still need to address wtr intrusion no matter what !

bdge's 2cy / .67cf per 80# bag = 81b of conc mix - 3 guys & an elec mixer can do that easily w/o any cold jnts,,, 2 of us just did 40b for a d/w throat w/o bustin' our a** ( i'm 71 & mixer was 45 ),,, compared to redi-mix 5cy min load + del chg + cleanout chg + whatever-else-they-add-on charges, bagg'd mix is the bomb ! good luck !
 
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Old 12-15-13, 12:37 PM
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Before the OP is lured into thinking she can batch, place and finish half of her garage floor's overlay, using Sakrete or Quikrete in 80-lb. bags, let's first make a few presumptions, and then crunch some numbers:

Volume of material will be about 50 C.F. (84 large sacks).
She won't be doing this completely by herself, unless she's Wonder Woman.
Hiring a 3-person crew with all necessary equipment will cost at least $44 an hour for labor and tools (2 grunts @ $12 + lead man @ $20).
Placement/finishing rate = 10 sacks per hour.
Three hours of surface prep and expansion joint setting time.

Total labor cost = $44 x (3 + [84/10] = $502
Total material cost = 84 x $4.25 +/- + $24 misc. (exp. felt, etc.) = $381

Grand Total = $883

Going with ready-mix would cut the labor time in half, and material cost would likely be a bit less, even with a small load charge included. Not to mention the advantage of far less chance of cold joints or the overlay debonding.
 
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Old 12-16-13, 03:43 AM
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no idea of gender as its not usually found,,, rather just whatever work needs doing

ea bag = .67cf so for bdge's 2cy, you need 81bags ( $3 per b ) + 2 or 3 b for spares,,, probably need a trk, too $ 250 - mixing directions on bag

place/finish 3-man crew's $550 / $ 650 here (atl) - 1/2day's work,,, min redi-mix load - $ 600 ),,, our costs were diy but this forum's diy,,, so hire manuel labor @ $ 110/$120d - pick 'em up, get the work done, buy 'em lunch, & take 'em back to the gas station,,, doubtful many folks want those safety issues - especially a single woman - but that may be chauvinist sexist thinking on my part

we mix'd our 40b in a wheelbarrow,,, if you stand around yappin', the work doesn't get done -just my opinion

THIS is the op - ' Maybe it is time to explain myself..we don't use the garage for parking..very rarely...was trying to cheap out by pouring concrete over and checking the scour at the wall edge..filling if necessary and then concreting over..worried that concrete would stick well to underlying pad if less than I inch or one inch thick '

didn't know o'lay was still in the running,,, won't recommend it based on op's comments nor do i like bonded o'lays of 2" or less of reg conc - that doesn't mean we haven't successfully done 'em - just don't trust 'em,,, in the end, it always comes down to $$$ (value)
 
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