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RCC Slab Leak - How to arrest.

 
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chendubaby
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PostPosted: Thu Aug 26, 2010 5:25 am    Post subject: RCC Slab Leak - How to arrest. Reply with quote

I noticed a problem in a RCC Slab of a 6 storied building. The slab is leaking at few locations in rainy season. The leak is in the middle portions of the slab, not at the corners or joints. what is the best and cheapest way to arrest the leaks.
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Dr. N. Subramanian
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PostPosted: Thu Aug 26, 2010 2:26 pm    Post subject: Re: RCC Slab Leak - How to arrest. Reply with quote

Dear Er Chendubaby,

Before arresting the leaks, you have to find out why there are cracks in the mid span. Unless you remove the root cause, the problem will be reoccurring.  Check whether it is due to inadequate reinforcement or due to temp.(inadequate weathering course), etc.

Note that repairing is always expensive and there is no cheap solution!
May be grouting the cracks is a possible solution.

Best wishes
NS
chendubaby wrote:
I noticed a problem in a RCC Slab of a 6 storied building. The slab is leaking at few locations in rainy season. The leak is in the middle portions of the slab, not at the corners or joints. what is the best and cheapest way to arrest the leaks.
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P.K.Mallick
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PostPosted: Thu Aug 26, 2010 3:22 pm    Post subject: Reply with quote

Pressure grouting from bottom shall help,provided if there is no structural cracks.
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chendubaby
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PostPosted: Thu Aug 26, 2010 4:11 pm    Post subject: Rcc slab leak due to poor workmanship Reply with quote

Thank you all for replying.

The cracks are mainly due to improper workmanship. The level is not proper and uniform. The slab is 6 years old.
Actually there is plan of going for a new layer.

Could you please let me know what is the method to be adopted for a new layer to arrest the leaks.

with regards

Premchand Mannava
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sspawar
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PostPosted: Thu Aug 26, 2010 5:19 pm    Post subject: Re: RCC Slab Leak - How to arrest. Reply with quote

Dear All

As per my knowledge, normal concrete is not considered as a impermeable substance.

If it is top roof  and leakages is due to the direct rains  -Then  brick bat coba water proofing treatment with a proper slope and draining out water is a cheaper solution.

Tarfelting (3 layers,  to 7 layers ) hunches preparation is also a cheaper one.

If it is at 'in between floors' and source and rout of water is not been identified or if it is as cointinues water retaining structure then - injection pressure grouting is the solution. .


But at the same time it is to be ensured that concrete quality and if plaster is there its quality also should be good, otherwise , honey combing or spelling out concrete and detoriate plaster has to be repaired first.


QUANTITY OF BRICK BAT COBA FOR ROOF - PER SQUARE METER OF SURFACE

DESCRIPTION                                 QUANTITY                      UNIT     

BRICK BATS                                     0.092                            CUM

CEMENT                                           0.43                              BAGS

SAND                                               0.092                            CUM

WATER PROOFING COMPOUND        0.43                              KGS

Thanks



chendubaby wrote:
I noticed a problem in a RCC Slab of a 6 storied building. The slab is leaking at few locations in rainy season. The leak is in the middle portions of the slab, not at the corners or joints. what is the best and cheapest way to arrest the leaks.
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skhalid
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PostPosted: Fri Aug 27, 2010 6:07 am    Post subject: Reply with quote

Dear Mr. C
hendubaby,



The reason u told is that poor workmanship. But my suggestion is that , please chek the deflection. Wether the slab is deflecting, for this you can paste a white  paper strips at the different locations & see wether the are tearing. Observe for a period of atleast 15 days.



Regards

S.M.Khalid
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sspawar
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Joined: 05 Jun 2009
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PostPosted: Fri Aug 27, 2010 12:38 pm    Post subject: Reply with quote

Dear  All

Will paper be firm there with the water drops and damp / moist surfaces.

In Place of paper make a strip of plaster there and cure it properly for 14days.
Later observe for few days.

But the question is that what is remedy to make it all proof.

It will not be advisable  to jump over the structuaral solution, it is required to study the type of cracks  its pattern, depth width etc.

Inplace of one line sagging, surface is found uneven.

Where  the structure is 6 years old with such leaking cracks, slab will structurally servive for a longer period after water proofing.

There are several such cases in cities that slab leakages in rainy seasons happened, and in 99 % cases  only water proof treatment is to be attained.

And there is no such cases in old buildings that a 2way/1way slab has been collapsed, before of wall column and cantilivers.


Regards

skhalid wrote:
Dear Mr. C
hendubaby,



The reason u told is that poor workmanship. But my suggestion is that , please chek the deflection. Wether the slab is deflecting, for this you can paste a white  paper strips at the different locations & see wether the are tearing. Observe for a period of atleast 15 days.



Regards

S.M.Khalid
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badamsundararao
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PostPosted: Sat Aug 28, 2010 5:37 pm    Post subject: CRACKS IN SLABS Reply with quote

Dear friend,


As seen from your information I feel that the depth is not sufficient to meet the deflection requirement hence instead of providing heavy brick coba layers ,better to go for pressure grouting and  providing of silicone coating is preferable.


badam sundara rao.
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sspawar
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PostPosted: Sun Aug 29, 2010 1:48 am    Post subject: Re: CRACKS IN SLABS Reply with quote

If size of tarrace is small, by simple slopy waterproof plaster layer will also solv the problem. or otherwise for larger area to maintain a slope one side 3 to 4" layer is common thing.

Tarfelting is also a light and cheaper solution. refer IS codes.

Injection grouting for most agressive patch can be taken, though it is costly.
Silicon or any epoxy base coat are costly affairs, for residential roof slabs (non water body structure)

Please refer codes -  purpose and type of water proofing - NBC,
1346,1580,1609,3036,3037,3067,3384,4365,4911,5871,6494 --------<xml><o></o>



Thanks
badamsundararao wrote:
Dear friend,


As seen from your information I feel that the depth is not sufficient to meet the deflection requirement hence instead of providing heavy brick coba layers ,better to go for pressure grouting and  providing of silicone coating is preferable.


badam sundara rao.
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