Ground Beams — Shambles

[johna.clements]

Looking at the white rectangle it looks like one of the piles will not be completely under the ground beam. Is this acceptable?

Tolerance on pile positions is normally 75mm. They like like they are slightly more than that but would most likely pass a design check.
it would be good to expand the ground beam locally around the pile with a few L bars to tie the concrete into the rest of the beam.

@marcus one thing that does concern me was how was the top of the piles treated. Is that the as cast top of the piles. Was the top few hundred mm broken off to remove the crude that floated up in the pile.

 

[johna.clements]

fair enough to protect it initially but it should be removed before the cages are placed, they should rest on the piles, not on the polystyrene. When the thing is done all that should be in contact with the polystyrene is concrete, with the steel embedded fully within in. Any steel left exposed will corrode and eventually weaken the beam.

If they remove the OSB before they place the cages they will be walking on the polystyrene. The polystrene is a mess already without feet and rebar ripping it up. I don't think that the OSB slowly rotting in a place where you want a void is a big problem.

The lack of spacer blocks is a problem.

 

[johna.clements]

Personally I would want the OSB out as I would not want a rot void at the bottom of my foundations with eventual risk of slight subsidence. If that is not as per spec then you have a good excuse to make them take the steel out and refit it properly this time, and do a decent job of the shuttering.

The polystyrene is compressible. When the clay expands it will compress. When the clay contracts the polystyrene may not completely expand so a void may be left.
The foundation is supported by the piles not the ground between so that the ground can move up and down without effecting the building.

 

[Fergie 307]

If they remove the OSB before they place the cages they will be walking on the polystyrene. The polystrene is a mess already without feet and rebar ripping it up. I don't think that the OSB slowly rotting in a place where you want a void is a big problem.

The lack of spacer blocks is a problem.

I would have expected the cages to be lowered in, so not sure why they need to walk on it. My main concern was that the cages appear to be resting directly on the osb. I am with the OP, that it maybe that at least in part it disguises the crazy paving approach to the polystyrene, which I dare say is not quite what the manufacturer had in mind !

 

[johna.clements]

The OSB is there to protect the expanded polystyrene from damage when it is walked on and the cage placed.
It also seems to be hiding that they have cut up the polystrene into bits rather than putting down one piece.

Yes @Fergie 307 as I replied before and as I posted there are problems with no cover and excess cover.


The two men would have carried the first cage in with one walking on the OSB rather than the muddy surround.
They then one lifted it up and the other one threaded some timber through the cage to get it up off the ground.
They would have then carried in the next cage and inserted and turned the long bars into the other cage.
Most likely again standing on the OSB because it is the only flat non slippy surface.

 

[MARK.B.]

The op mentioned that the cages were built in situ on site,i think maybe the OSB was used to make it easier for them to do this.

 

[marcus]

Thanks for your continuing responses, all been very helpful, things are going better now

 

[ChaiLatte]

My main concern was that the cages appear to be resting directly on the osb.

Somewhere above in what has become 'War and Peace', the OP says the footing has water in it that will subsequently be pumped out. Polystyrene and OSB float on water.

 

[marcus]

I now know more about reinforced concrete than I thought I ever needed or wanted to

 

[johna.clements]

I now know more about reinforced concrete than I thought I ever needed or wanted to

We have only scratched the surface but I do not think that there is enough people here to turn it into a "sharpening thread"

Good to here that it is going better now,

 

[Superduner]

Ah, now dewatering excavations. A whole new topic to explore!
Did I ever tell you about the dewatering of Dubai Marina...... ?

 

[johna.clements]

Ah, now dewatering excavations. A whole new topic to explore!
Did I ever tell you about the dewatering of Dubai Marina...... ?

Didn't the lack of water make it difficult for the boats.

 

[Superduner]

It quickly became apparent that this was, indeed, a problem, so we rewatered it.