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Cold Joint in Column
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Er.Ajith_K
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PostPosted: Mon Oct 16, 2017 3:21 pm    Post subject: Cold Joint in Column Reply with quote

Hi,

I had discussion with my senior engineer about the cold joint in column. If it is 3metre long column, he said he would prefer two lift (1.5 metre - First lift and another 1.5 metre - Second lift). The reason he gave me was due to formwork. The timber formwork will get affected due to vibration and other factors like climate, which may lead to slight bulge of column (range of 3-7mm) in repetition. So if we pour concrete for 1.5 metre box, we can have proper compaction and control over the formwork. In this case, we will have two joint - one is at the middle of the column and another is at the slab. I have few question to the engineers in this forum. I would like to know your opinion.

1.     Can we provide cold joint in column?
2.     If yes, then at what location can it be provided? Middle of the column or at end of the column?
3.     Is cold joint in column is allowed in earthquake resistant building?
4.     What do you prefer - constructing column with two lift (1.5metre first lift and 1.5 metre second lift or single lift (3 metre - single lift)?
5.     Please kindly share if there is reference or codal provision for this.

With Regards

Ajith Karunanithi
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shefypattambi
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PostPosted: Tue Oct 17, 2017 6:26 am    Post subject: Reply with quote

Hi,
I believe your senior engineer suggestion is right when comparing to the maximum allowable pouring height of concrete as per IS code. I believe it is 1.5m.
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Er.Ajith_K
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PostPosted: Tue Oct 17, 2017 7:24 am    Post subject: Reply with quote

Hi,

Yeah your right that maximum permissible free fall for concrete is 1.5 metre. My senior engineer told to make 1.7 metre long column box. The first shift will be poured for 1.7 metre and it will be removed next day and erected for second shift for 1.5 metre concreting. Is this practice acceptable ?


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Ajith Karunanithi
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shefypattambi
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PostPosted: Tue Oct 17, 2017 8:48 am    Post subject: Reply with quote

I am sorry. I dont know that the next day itself you can cast the second lift of the column. However when you are casting the second lift please make sure a proper surface preparation (like Rough surface) on top of the first lift column to receive the second lift column.
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es_jayakumar
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PostPosted: Tue Oct 17, 2017 2:33 pm    Post subject: Reply with quote

Er.Ajith,
The "CPWD Specifications" (Vol.I) at Cl.5.4.2.4 restricts the vertical drop of concrete for columns to 1.5 metres, in order to avoid seggregation. This will necessitate the casting operation in 2 or more lifts. You may take precautions as suggested by Er.Shefy

E S Jayakumar
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Er.Ajith_K
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PostPosted: Tue Oct 17, 2017 5:01 pm    Post subject: Reply with quote

Dear sir,

As per CPWD Specification Volume  Cl.5.4.4.2 "In case of columns the joints shall be horizontal and 10 to 15 cm below the bottom of the beam running into the column head. The portion of the column between the stepping off level and the top of the slab shall be concreted with the beam."

They have provided this clause under Construction Joints. I guess both cold joints and construction joints are same. In this case you can't pour the concrete from 1.5 metre height.


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Ajith Karunanithi
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Dr. N. Subramanian
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PostPosted: Tue Oct 17, 2017 7:15 pm    Post subject: Reply with quote

Dear Er Ajit


As I am in India now, I can not quote the exact reference. But I believe that I have written about this in the forum on an earlier occasion. As per research conducted in USA, much higher heights of pouring of concrete (46 m!)has resulted in no segregation. You may Google"B.A.Suprenant+Free fall of concrete" and also my posting here dated Feb 3rd 2012.

Regards
NS
es_jayakumar wrote:
Er.Ajith,
The "CPWD Specifications" (Vol.I) at Cl.5.4.2.4 restricts the vertical drop of concrete for columns to 1.5 metres, in order to avoid seggregation. This will necessitate the casting operation in 2 or more lifts. You may take precautions as suggested by Er.Shefy

E S Jayakumar
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shefypattambi
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PostPosted: Tue Oct 17, 2017 8:43 pm    Post subject: Reply with quote

Dear Dr.NS Sir,
That news is interesting. I have seen many buildings here in UAE which the columns were constructed at 3.5 to 4 m height at one time and next day they will move the shuttering to another location and I did not seen any honeycombing at the bottom of columns except rare cases. Mostly the concrete is readymix with good admixtures for work-ability and the workers are putting the needle vibrator out side of the shutter at the bottom side.
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es_jayakumar
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PostPosted: Wed Oct 18, 2017 2:31 am    Post subject: Reply with quote

Happy Diwali to all........ Interesting discussion.... I hope it is high time the specification in this regard is re-written. Practically, the height of lift / drop will be kept more than 1.5m in most of the cases. When it is high, we have to ensure the proper compaction of bottom layers, in view of difficult reach. Subramanian sir's posting could not be traced.

E S Jayakumar
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Er.Ajith_K
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PostPosted: Wed Oct 18, 2017 2:48 am    Post subject: Reply with quote

es_jayakumar wrote:
Happy Diwali to all........ Interesting discussion.... I hope it is high time the specification in this regard is re-written. Practically, the height of lift / drop will be kept more than 1.5m in most of the cases. When it is high, we have to ensure the proper compaction of bottom layers, in view of difficult reach. Subramanian sir's posting could not be traced.

E S Jayakumar



Dear Jayakumar,

Happy Diwali to you and your family. I traced out Subramanian sir post. The link to the post is given below:

https://www.sefindia.org/forum/viewtopic.php?p=44033


With Regards


Ajith Karunanithi
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