use of water instead of vibration for pile work

[jownn]

I am currently supervising a multi story building that requires a shoring piles with 1meter diameter, 18 meters depth and 0.8 m distance b/n piles the contractors are pouring the concrete while there is water as high as 3 meters and without use of vibration they use admixture superplasticizer( pce) what is your thoughts

 

[Retrograde]

What do you mean by "while there is water as high as 3 meters"?

 

[jownn]

there is water in the bottom of the hole due to high water table as high as 1 meter but on top of that they add additional water which they reason that it increase the strength of the concrete by removing the entrained air as it is displaced by the concrete

 

[SlideRuleEra]

jownn - Concrete can be placed underwater... but not by pouring it from the top. When concrete is poured into water it will segregate.

To place concrete correctly underwater it has to be forced upward, beginning at the bottom of the hole. This is done with a "hopper and tremie pipe" or a concrete pump.

Here is a link to a magazine article with a description of underwater concrete placement: Placing Concrete Under Water

Here is a diagram and photo of a hopper and tremie pipe in use.

http://www.SlideRuleEra.net

http://www.VacuumTubeEra.net

 

[hokie66]

Nothing about this sounds right. Water never increases concrete strength. Neither does entrained air reduce concrete strength.

What type wall is this? If it is a secant pile wall, and these are the "soft" or "female" piles, possibly they know what they are doing but are playing games with you.

Is the concrete being placed by tremie?

Your attachments can't be read.

 

[allgoodnamestaken]

It sounds to me like they're adding water to the concrete in the trucks as they show up, but that definitely won't increase strength. More water = weaker concrete. If they didn't add a plasticizer and they aren't vibrating it, you're going to have bad consolidation. If they add water to make it more workable, you're going to have weaker concrete. If they're pouring concrete into holes with 1 meter of water in them, that's not going to make anything good.

Nothing here sounds like its going right.

 

[cvg]

typically, extra cement is added to underwater concrete mix to account for potentially lower strength when placed. An anti-washout admixture could be used to improve the results

 

[jownn]

they use tremie construction & they use admixture(superplasticizer) but my question is what is the benefit of adding water to the hole before concreting starts

 

[jayrod12]

Zero benefit. In fact it would make placing of the concrete harder. I don't see a scenario where filling a hole with water prior to filling it with concrete could be desired.

 

[hokie66]

You didn't answer my question. If it is a secant pile wall, and these are the "soft" piles, I can think of reasons for doing this.

 

[jownn]

it is not a secant pile it is a soldier
pile/ shot crete retaining wall