concrete pour

[rsavani]

Hi,

What is recommended Height of Horizontal joint on 500mm thick and 5.5 mt. high vertical wall of water reservoir?
Or no need of horizontal construction joint.

thanks for your time,

rakesh

 

[kelowna]

It can be done without horizontal joints. It depends on your specific configuration and formwork design

 

[Ron]

Agree. No need for horizontal joint for this size placement, assuming your vertical divisions are reasonable. This size will need a truckload about every 3m to keep it moving and prevent cold joints. Assuming about 10 minutes to discharge each truck, you'll need to stage the trucks so that they are available, but not waiting too long in queue.

 

[cntw1953]

Are there rules of thumb for horizontal joint besides the capability of placing in one continuous pour?

 

[rsavani]

Hi,

Thanks for your reply. What is time to monitor cold joint for different mix? is there any handy table available? We have difference of tem too; start at -5 and at end +7.

Ron- please corrects me if I understand your second sentence wrong. We pour wall full height at 3mt length. if we do so how we can vibrate concrete.

Thanks again.

rakesh

 

[cntw1953]

You shall make several lifts, each goes around the wall to a height that can be thoroughly vibrated without over stress the form. The speed of concrete pour, and tendency for aggregate seperation (from travel too far) will impact the distance of a lift in order to avoid cold joint, and inadequate vibration that might results in honeycomb.

What is the -5, +7, temperatures? I don't see the relevance if concrete and environment are controlled per requirement for cold region concreting. I could be wrong though.

 

[JedClampett]

I would stay away from horizontal joints. Contractors can pour 30 or 40 ft. of vertical concrete. Adding horizontal joints means more waterstops and vertical laps which add up to rock pockets and folded waterstop.
I've used a horizontal joint to step a wall in a lift station to save concrete. But lift stations have subtle differences, with varying water levels vs a reaervoir. Most of the action in a lift station is within 8 to 10 ft from the base. With a reservoir, there are advatages in using the full depth, which puts the horizontal joint in play.

 

[Ron]

rsavani...as cntw1953 noted, you place the concrete horizontally and vibrate as it is placed. You just need to make sure that you have the trucks staged and the crews available to have a continuous placement from one vertical stop point to the next. You will need a large crew, multiple vibrators, a coordinator for the truck staging and queueing, traffic control perhaps, etc. This will be a large undertaking and needs to have appropriately trained and qualified individuals.

JedClampett noted the need to avoid horizontal joints. You need to make sure you get continuous concrete placement to avoid a horizontal or vertical cold joint....which will leak!

 

[rsavani]

Hi,

Thanks for all replies.
thanks

rakesh

 

[Elfarra]

I think that you need to add a little of liquid plasticize into admixtures concrete mortar.

Kind regards
Elfarra

 

[FrCivEng]

Concrete pouring for water tank wall height 5,5 m :

- No horizontal joints (not allowed by several codes)
- No problem to pour in one time ; depending on the method statement for concrete production + delivery + bucket lifting + pouring + vibrating, you have to plan vertical joints with stainless steel plate and hypalon seal in the centre and additionall rebars at the cold joint,
- The method statement will give you the detailed time schedule depending on available batching plant capacity and truck mixers (nb, capacity) and distance from production area to cosntruction site
- This time will impact the concrete mix design and may be impose to use a plasticizer and /or a set retarding admixture
- Trials mixes and tests are highly recommended to check concrete consistency (sump) as it will need proper vibration at 5 m depth
- Using tremi-pipes is recommended to limit at max 1,00 m the free drop height in order to avoid segregation
- Vibration is very important to avoid segregation and honeycomb defects, it shall be properly designed and organized,
- For a 500 mm thick wall, concrete temp should be monitored and formwork removal allowed when temperature difference between concrete surface and outisde becomes less than 20°C .

 

[diggerman]

AVOID that horizontal joint at all costs. That's just an accident waiting to fester. As long as you treat the pour similar to that of a shear wall. The contractor should have a well hand on this. And yes Mr. Ron knows his stuff it appears. Keep concrete consolidated and keep that v-brator going and you should be A-OK!