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Concrete Pouring Height

 
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gpsarathyy
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PostPosted: Thu Feb 02, 2012 5:36 am    Post subject: Concrete Pouring Height Reply with quote

Dear Sefians,

Can anybody tell me, how much height is allowed for pouring the concrete (free flow, without any tremie pipe etc) as per IS code without seggregating the concrete, displacement of reinforcement, built in items, or movement of, and damage to faces of formwork.

If possible please give the IS code reference also.

Regards,
G.Parthasarathy
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suresh_kumar
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PostPosted: Thu Feb 02, 2012 9:17 am    Post subject: Reply with quote

Dear sir

Dropping concrete from too great a height causes the finer particles in the mix to splash away from the larger, heavier particles. In addition, theforce of the mix striking the reinforcing steel may shift bars out of
position. The maximum drop height or allowable free fall is 5 ft.
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N. Suresh kumar
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sspawar
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PostPosted: Thu Feb 02, 2012 10:52 am    Post subject: Re: Concrete Pouring Height Reply with quote

Dear  ER.Parthsarathy

AS Per IS 456 Clause13 TRANSPORTING, PLACING,
COMPACTION AND CURING
13.1 Transporting and Handling
After mixing, concrete shall be transported to the
formwork as rapidly as possible by methods which will
prevent the segregation or loss of any of the ingredients
or ingress of foreign matter or water and maintaining
the required workability.
13.1.1 During hot or cold weather, concrete shall be
transported in deep containers. Other suitable methods
to reduce the loss of water by evaporation in hot
weather and heat loss in cold weather may also be
adopted.
13.2 Placing
The concrete shall be deposited as nearly as practicable
in its final position to avoid rehandling. The concrete
shall be placed and compacted before initial setting of
concrete commences and should not be subsequently
disturbed. Methods of placing should be such as
to preclude segregaion. Care should be taken to
avoid displacement of reinforcement or movement
of formwork. As a general guidance, the maximum
permissible free fall of concrete may be taken
as 1.5 m.
13.3 Compaction
Concrete should be thoroughly compacted and fully
worked around the reinforcement, around embedded
fixtures and into comers of the formwork.
13.3.1 Concrete shall be compacted using mechanical
vibrators complying with IS 2505, IS 2506, IS 2514
and IS 4656. Over vibration and under vibration of
concrete are harmful and should be avoided. Vibration
of very wet mixes should also be avoided.
Whenever vibration has to be applied externally, the
design of formwork and the disposition of vibrators
should receive special consideration to ensure efficient
compaction and to avoid surface blemishes.

Regards
gpsarathyy wrote:
Dear Sefians,

Can anybody tell me, how much height is allowed for pouring the concrete (free flow, without any tremie pipe etc) as per IS code without seggregating the concrete, displacement of reinforcement, built in items, or movement of, and damage to faces of formwork.

If possible please give the IS code reference also.

Regards,
G.Parthasarathy
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gpsarathyy
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Joined: 28 Jun 2010
Posts: 481
Location: chennai

PostPosted: Fri Feb 03, 2012 5:40 am    Post subject: Reply with quote

Dear SSPawar & Suresh kumar,

Thanks for your immediate reply.

Regards,
G.Parthasarathy
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vikram.jeet
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PostPosted: Fri Feb 03, 2012 7:37 am    Post subject: Concrete Pouring Height Reply with quote

IS 456 (2000)
As already posted by Er SS Pawar sahab, the maximum permissible free
fall of concrete may be taken as 1.50m .(as per clause 13.2 of IS456)

I think this lift limit is from practical considerations.

Just to add from other codes - - - - - -

IS3370 part -1(1965)
(Clause 9.5.3 )
construction of walls
The height of any LIFT shall not exceed 2.0m unless special precautions are  
taken to ensure through compaction throughout by mech vibration or by  
other suitable means.


IS3370 part -1(2009)
construction of walls
(Clause 11.4.1 )
Height of any lift should be as large as possible.It is desirable to place the  
concrete to full height of member in one go.Thorough compaction by  
vibration shall be ensured.


IRC-21 (2000)
Clause 310.5.1
Under no circum stances concrete shall be dropped freely from a  
height of more than 2.0 meters.


best regds

vikramjeet


Dear Sefians, Can anybody tell me, how much height is allowed for pouring the concrete (free flow, without any tremie pipe etc) as per IS code without seggregating the concrete, displacement of reinforcement, built in items, or movement of, and damage to faces of formwork. If possible please give the IS code reference also. Regards, G.Parthasarathy
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vikram.jeet
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PostPosted: Fri Feb 03, 2012 7:55 am    Post subject: Concrete Pouring Height Reply with quote

Hence it can be inferred from various codes that upper limit of pouring lift  
is 2.0m but practical and desirable is 1.50m.

For water retaining structures , it is advantageous to pour in one lift of full
height as far as possible to avoid use of water bars/ and for leakage control.

best regds

vikramjeet
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Dr. N. Subramanian
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PostPosted: Fri Feb 03, 2012 4:43 pm    Post subject: Re: Concrete Pouring Height Reply with quote

Dear Er Parthasarathy,

Sorry, I could not reply soon. It is a very good question.

Sometimes specifiers and inspectors dictate the maximum free-fall distance of concrete because they believe limiting free fall is necessary to minimize concrete segregation. Usually they limit the free-fall distance to 3 to 5 ft (0.9 to 1.5 m), but occasionally the limit can be as little as 2 ft (0.6 m).

None of the standards, e.g.. IS 456, ACI 301-99, “Specifications for Structural Concrete,” nor ACI 318-2011  limit the maximum distance concrete can free fall.

In 1999, the Federal Highway Administration eliminated its 25 ft (8 m) free-fall limitation and now allows unlimited free fall of concrete[1].

At least four field studies have shown that free fall from great distances doesn’t reduce concrete quality. Although all the field studies have been for caissons,
the results should also apply to other structural elements such as walls, columns, and mat foundations[2].

In the Chicago area, contractors routinely construct concrete caissons by allowing the concrete to free fall to depths of up to 150 ft (46 m). Full length cores taken from more than 100 of these caissons over a 30-year period have shown no evidence of segregation or weakened concrete[2].

Free fall of concrete from heights of up to 150 ft (46 m), directly over rebar or at high slumps, have not found to cause segregation, or reduce compressive strength[1-3].

Thus Bruce A. Suprenant , Vice President of Engineering and Technical
Services for Baker Concrete Construction concluded that restricting free-fall heights does decrease concrete production rates, increasing owners’ costs without increasing concrete quality
[2].

Recently, the Concrete Casting Committee of the Instituto del Cemento y del Hormigón de Chile (ICH) has developed Technical Specification
ET 002-05, “Dumping Height of Concrete when Casting Vertical Elements.” proposed the following{4]:

Slump    Dumping height     Pumpable
<80mm        2m        No
>80mm        2.5m        no
>80mm        3.0m        yes

References:
[1]FHWA, Drilled Shafts: Construction Procedures and Design Methods, V. 1, FHWA-IF-99-025, Aug. 1999.
[2] Suprenant, B.A. Free Fall of Concrete, Concrete International, ACI,June 2001, pp.44-45.
[3]Turner, C. D., “Unconfined Free-Fall of Concrete,” Journal of the American Concrete Institute, American Concrete Institute,
Farmington Hills, Mich., Dec. 1979, pp. 975-976.
[4] Manasa,C. Concrete Dumping height Specification, Concrete International, ACI,Feb 2008, pp.40-42

gpsarathyy wrote:
Dear Sefians,

Can anybody tell me, how much height is allowed for pouring the concrete (free flow, without any tremie pipe etc) as per IS code without seggregating the concrete, displacement of reinforcement, built in items, or movement of, and damage to faces of formwork.

If possible please give the IS code reference also.

Regards,
G.Parthasarathy
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suraj
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PostPosted: Sat Feb 04, 2012 1:05 pm    Post subject: Concrete Drop Reply with quote


  1. Concrete drop should be maintained from 1.5 to 2 m maximum.
  2. There is no limit for casting height in one go, as far as this drop limit is maintained.
  3. In case, pump is used, pump boom outlet pipe portion can pass through vertical section & maintain drop restriction.
  4. Smaller dia boom pipe can also be used in vertical section using reducer connection, provided, drop is maintained.

_________________
Thanks & Warm Regards
IntPE(India)Suraj Singh FIE Civil
Engineering & Arbitration

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Kumar_Abhishek_Singh
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PostPosted: Wed Oct 18, 2017 9:02 am    Post subject: Reply with quote

Enclosed file/picture shows how WE do the cold joint in column (only when absolutely necessary). Additionally,

1. We design the column rings around the joint to take 100% shear...no concrete capacity taken.

2. Dowels are additional precaution. Concrete notch/shear key is also additional precaution (you can calll it 'redundant'). Why, because if I am forced to give a cold joint in column that means that the workmanship of the contractor is questionable (if he cant make a 3m column in one go, what else can he make) and that I cant trust him with quality of steel being used etc etc...so I have my ways of saving myself.

3. Our codes need to have specific clause for this. Alas, even ACI-318 cl 6.4.3 (if my memory is right, its written in the commentary of 6.4.3) doesn't give full picture. We can design for shear using shear friction design method of 11.6 of ACI-318.

Hope this helps...

Abhishek



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