Pre-fabricated sub floor planks

[r136dg]

They set the pre-fabbed planks last night in the rain and what a fiasco. Anyways, my concern is after they've welded their small beads on those little tabs there's still play in the rooms with longer planks (like a very mild trampoline affect). It's not too much but enough to really bother me. They're going to pour 5cm of concrete over this today. Will this create a solid floor for years down the road? Should rebar be welded to any of the tabs or hooks in the plank maybe? Any thoughts or suggestions much appreciated!

By the way, I posted the columns topic a couple days ago. I'll post results on that with pics later, but for now I can say no big issues on that gig.

Thanks!

[Strange]

Do you have any pics of the tab/hook/plank concern? I got you about the trampoline effect, not too concerned about that, just want to make sure the issue is clear. 

 

But from the sounds of it, appears normal except they should roll out a wire mesh deal before pouring, and 5 cm is a little thin for my liking but should be fine. I would have gone for about 7cm before starting to feel comfortable but 5 should be okay. 

 

Pics if you can. 

 

2 hours ago, r136dg said:

By the way, I posted the columns topic a couple days ago. I'll post results on that with pics later, but for now I can say no big issues on that gig.

 

Glad to hear it. Not really as weak as you initially thought right? 

[eyecatcher]

50 connie on 50 plank is standard but as Strange mentioned nothing further required apart from the wrapping mesh over the whole area.

there should not be any need for welding at all and the tabs on the top of the planks are simply the lifting eyes they use to carry them by crane or manually.

 

The planks have no where to move to as they would normally be set back about half the width of the carrying beam 50 to 100mm and prior to concreting this edge would be shuttered so your floor edge should be a full 100mm of concrete.

my planks were spanning about 3.6m unsupported at first floor level and 500 wide, no deflection at all; though having said that I did insist they bamboo prop the underside for a week until the whole floor was acting as one.

if you are doing an upper floor next, this is imperative.

[r136dg]

They did mesh it & the subcontractor poured 7cm instead of the 5 the general wanted so that worked out well, really well! There's a pic in here of the pre-fab crew welding the tabs (in the dark & rain). They were fast & didn't knick any columns. Today they poured the bathroom floors reinforced with rebar every 20cm squared @ about 12cm thick. Hope we never get any leaks in pipes under those floors;-) 

I've been overthinking & worrying for nothing it appears. I'm impressed with these concrete guys. I think they liked me for not being afraid to get dirty & jump in to assist at times, had handy tools for them & no doubt they new I was a prior cement head. The only thing that really bothered me was all the water they add. Probably why they don't use wheel barrows for pours.

RE my columns post; Only 1 spot peeled from the early stripping (they patched it immediately) and they sealed them up right away to slow the curing. 

 

Thanks for the suggestions & putting me at ease gentlemen!

Wait for the roofing crew now.

 

[Strange]

21 hours ago, r136dg said:

RE my columns post; Only 1 spot peeled from the early stripping (they patched it immediately) and they sealed them up right away to slow the curing. 

 

Is your last pic a picture of the early stripping damage ur talking about? 

 

FYI that last pic has nothing to do with stripping the forms early or curing. 

 

Thats entirely the result of a less than optimal mix/dry spot/rock heavy/un-settled pocket. 

 

Now with that said, its gonna happen. In the professional world its the reason that companies use vibrators with pouring concrete. Constantly pouring, dipping the vibrator in, pouring etc... 

 

Here they pour it and hit the form with a hammer to get the cement to settle. 

 

No big deal, house won't fall down, but a notable example as to why its important to do what you can to get the cement to settle as your pouring it. 

[stubuzz]

22 hours ago, r136dg said:

I've been overthinking & worrying for nothing it appears. I'm impressed with these concrete guys. I think they liked me for not being afraid to get dirty & jump in to assist at times, had handy tools for them & no doubt they new I was a prior cement head. The only thing that really bothered me was all the water they add. Probably why they don't use wheel barrows for pours.

Why are you impressed? They added water and weakened the mix and were poorly equipped and had to use your tools.

[Strange]

11 minutes ago, stubuzz said:

Why are you impressed? They added water and weakened the mix and were poorly equipped and had to use your tools.

 

Witch, in all fairness, is pretty normal for Thailand & hardly anything to lose sleep over or get stressed about. 

[r136dg]

12 hours ago, stubuzz said:

Why are you impressed? They added water and weakened the mix and were poorly equipped and had to use your tools.

As much as I cringed, adding water was a conflict I didn't want to get into. Probably similar to telling farmers here to till instead of burn. Just something that's easier & done for millennia. They didn't have to use my tools, only asked for a chalk line once. But leaving a wheel barrow, laser level, ect was just done in good faith. They didn't need the snacks my wife left there either. But in the end, I think we got better back filling, thicker concrete (in areas),, more reinforcement & delivered redi-mix (in 1 pour) where hand mix was slated. 

Just my take on it,

Thanks again!

[CGW]

15 hours ago, stubuzz said:

Why are you impressed? They added water and weakened the mix and were poorly equipped and had to use your tools.

You taking the day off from "motivational" speaking 

 

The water will off course weaken the concrete, possibly by up to 50% dependent on the original "design". In this instance does it matter^ IMO a resounding No, If the concrete becomes so stiff its unworkable I would rather have some concrete in place than non at all! - so add some water. For the purpose intended the concrete was pored, the loss of strength is totally immaterial, I would guess initial design was around 4,000 psi, now its weaker! what is the chance of failure?

I have never heard of anybody falling through a floor in Thailand as the "mix" was too wet! Buildings falling down due to bad concrete - yes, but the floor cant be considered part of the buildings structural integrity so its really no Big deal! I would have been happy with the job.

[stubuzz]

6 hours ago, CGW said:

I have never heard of anybody falling through a floor in Thailand as the "mix" was too wet! Buildings falling down due to bad concrete - yes, but the floor cant be considered part of the buildings structural integrity so its really no Big deal!

So, do you think that they are not going to water down the mix (to make thing easier for them) when they are pouring the piles and the first floor?

 

If you are paying the workers, tell them not to add water. If they don't listen, find a crew that can follow instructions and the designers specifications.

[CGW]

^ Sounds like a very practical solution! have you built a house in Thailand?

[r136dg]

Well, in my case, I'm not worried at all now. Sure was when I originally posted though.

They didn't add water for the columns pour & it was exactly as Strange stated; no vibrators, just taping the forms with hammers. Water was added for all the flat work, including the garage. But it's all thick enough, well reinforced, on stabil soil or footings (beams), blessed with cool weather and someones keeping it wet when the suns out. It will gain plenty of strength through the slower cure & once tiles on it..................

Thanks!

[stubuzz]

Over-watered concrete tends to shrink and crack. You might want to wait a while before laying the tiles.

[grollies]

On 19/12/2016 at 6:13 PM, Strange said:

 

Is your last pic a picture of the early stripping damage ur talking about? 

 

FYI that last pic has nothing to do with stripping the forms early or curing. 

 

Thats entirely the result of a less than optimal mix/dry spot/rock heavy/un-settled pocket. 

 

Now with that said, its gonna happen. In the professional world its the reason that companies use vibrators with pouring concrete. Constantly pouring, dipping the vibrator in, pouring etc... 

 

Here they pour it and hit the form with a hammer to get the cement to settle. 

 

No big deal, house won't fall down, but a notable example as to why its important to do what you can to get the cement to settle as your pouring it. 

got to agree here. I built a pool early this year and since my builder didn't own a concrete vibrator I bought my own. Mind you the base pour was 400mm. also used it when filling between the walls.

Not used it since but I got a pumphead to fit the Honda motor. Two for one.

If I was building a house here it would be worth the investment IMO. Global House bout 15,000 THB 

[jvs]

You want to make sure you don't use the vibrator too much,it makes the gravel sink

to the bottom.Weaker concrete could be the result.

[grollies]

6 minutes ago, jvs said:

You want to make sure you don't use the vibrator too much,it makes the gravel sink

to the bottom.Weaker concrete could be the result.

Yep and we had a way of checking this. After the base had gone off I checked the levels and he was off in one corner area about 10mm. I got him and the crew (and me) to chip down about 10mm over around 6m2 before applying a bounding agent and relaying the repair. There was plenty of stone around!

[eyecatcher]

On 12/20/2016 at 10:24 AM, CGW said:

You taking the day off from "motivational" speaking 

 

The water will off course weaken the concrete, possibly by up to 50% dependent on the original "design". In this instance does it matter^ IMO a resounding No, If the concrete becomes so stiff its unworkable I would rather have some concrete in place than non at all! - so add some water. For the purpose intended the concrete was pored, the loss of strength is totally immaterial, I would guess initial design was around 4,000 psi, now its weaker! what is the chance of failure?

I have never heard of anybody falling through a floor in Thailand as the "mix" was too wet! Buildings falling down due to bad concrete - yes, but the floor cant be considered part of the buildings structural integrity so its really no Big deal! I would have been happy with the job.

 

That's a very pragmatic view which I agree with.

Being from the other side, the design side its clearly obvious that there is too much unnecessary engineered design going into everything we build for the sake of health and safety.

You are right of course, no one has fallen through a concrete floor, a roof has never collapsed and in England you dont have to go far to see buildings built 100-500yrs ago still standing strong.

I am not surprised western world construction is so damned expensive

 

But for the sake of our Western knowledge we have to keep that stiff upper lip and tell the little blighters they are doing it wrong.....don't we?