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[David232]

hello engineers. I am glad to share my experience. you should first examine carefully the reason of leakage then consult with professional of room leaking. if I suggest you then it will be dakonders, a best roofing ompany will solve your problem. you can visit here

I'm from Seawoods, Nerul, Navi Mumbai.

I have a flat in a society of 33 buildings (G+3) consisting of around 400 flats, built by central government agencies about 27-30 years ago, the warantee of which has expired as the residents have modified their flats.

However, the ceiling of my flat (and many others) is in a very bad condition. A portion of the ceiling of one room has fallen on its own (nobody is hurt). When we started the repairing work (with society's permission) it's found that the rods inside the ceiling are rusted badly. We feared that the whole ceiling will fall and stopped the work. You may check the photographs attached.

However, the society is dilly-dallying to appoint structural engineers to assess the situation and seek professional advices. In one of the other flats, you can see the upper flat through the ceiling--and it's like that since last 8 months or so, because of the society's indecision.

My query is, is it required to completely remove and redo the entire ceiling slab, involving the floor of upper flat? In case, the upper flat resident does not allow to do the work, and at the same time, society is also not able to appoint qualified structural engineers and start the work, what legal protection/action can I take? Is there any way to do something from inside our flat to stop the ceiling from falling (like, putting iron beams below the ceiling or of that sort).

It's a senior citizen's query who is completely a layman in this regard. Kindly help.

Thanks in advance...

Best regards....[/quote]

[vikram.jeet]

Dear Sir ,

Being a Sr Citizen , I can understand yr plight . The problem of rusting of bottom reinf bars , thereby chipping off the covering concrete is commonly seen in rcc slabs . There could be many reasons of rust. Ingress of water from open roof , from toilets , kitchen  ( mostly the traps are found leaking becoming source of leakage to lower floor dweller).

Following may be done immediately :
(i) please provide one (or two if room is big) nos Steel girders ISMB 200 @ 25.4 kg/m /  OR ISMB150 @14.9kg/m   as per design dictate along short direction OF ROOM  and resting on long walls.  This will save you as well as yr upper neighbour' from any mishap . If he can contribute in expenses of girders  for strengthening of slab  , well and good otherwise bear these expenses yrself as wise man.
(ii) Chip off all covering concrete which has loosened  and remove rust from bars thru sand paper as possible , fix thin wire mesh thru nails on exposed ceiling and apply mortar 1:3 cement and coarse sand on ceiling to cover reinf as well wire mesh . Cure it for a day and further plastering with 1:3 CEMENT & and fine sand.

(iii)  3rd most important is that request yr upper neighbour  to allow yr plumber to seal sides of all traps of kitchen,  toilets so that further deterioration  is prevented. Sealing can be done using white cement mixed with water proof and khaarra Soda (for early setting) . As a good neighbour , he may allow this since he is not to pay for this activity.

(iv) Yes   as a good neighbour for yr under floor dweller , pl seal  all traps from sides in yr home.

Just a view from designer , but construction expert can also suggest better ways to deal with ageing structures.

[KANNAN.M]

Hi All,Seen the picture of the damaged slab.this can be restored, some suggestions are given.
These  structural damages,distress,  occur due to various reasons say 
1. Age of the building or concrete,presence of salts Ca & Mg 
2.Poor quality of concrete, and permeability 
3) This distress in concrete and corrosion of steel in concrete is  due to the presence of salts Ca & Mg than its permitted limit .
The present  strength of the slab can be ascertained by conducting various NDT like
 rebound hammer, upv, half shell potential ...test etc. 
The presence of  salts Ca & Mg   may be tested.
Repair methodology can be adopted on the basis of NDT results.
The following types of  Repair methodology can be adopted depending on the damages of the structure 
1polymer modified concrete,
2.Injection epoxy grouting to increase the strength,
3.Anticorrosive coating ,Replacement or adding of new rears may be adopted. finally concreting with
4.Micro concrete or SCC M40 with superplasticizers 
By which this member can be repaired and rehabilitated. Finally it can be tested again with upv for  confirmation and  increase or restoration  of the required strength of the concrete.
Some sample damages/ distressed photographs showing the condition of concrete columns and a slab of a  Twenty storied residential structure, having 12 blocks ,and  1600 houses located at CHENNAI, for which  our team has suggested methodology for restoration, & rehabilitation.And the building is now  under restoration.

Kannan.M
9486100506














On Thu, May 19, 2022 at 3:30 AM Seshadri <forum@sefindia.org (forum@sefindia.org)> wrote:

[quote]            Hi All,My proposal to arrest damage is below. Before that, why I have a different take on a few points made by esteemed engineers. 
1. The spalling is due to corrosion.
2. Spalling occurs only in the cover, and has happened at a few spots; so that is unlikely to be a structural  issue yet considering ceiling slab is not expected to take building load.
3. Clearly, concrete is of poor quality and very porous.
4. Sacrificial anodic protection has a short life - depends on the quality of concrete and the thickness of the member. From the spall pix and considering it is 100-150mm thick slab, anodes are likely to dissolve in just  2-3 years; and to be effective even for that period, should be installed at regular intervals across the slab necessitating opening of covercrete and repairs. 
5.Cathodic protection is right if the problem were due to continuous and unstoppable chloride ingress;  sea breeze from the creek at Nerul can bring  chlorides, but ingress cannot be continuous nor unstoppable - a good protective coating can stop. 
My Diagnosis:
Spalling seems to have occured due to water ingress from upper floor wet areas. If additional signs of fungus on interiors, or of paint blistering / peeling is seen, the suspicion is confirmed.
If so, the upper floor bathrooms and wet areas etc should be made watertight; all embedded water pipes must be ensured watertight.
If there are no confirmatory signs of water from the floor above, the most likely cause of corrosion is  contamination in concrete. At least in the concrete used for the affected slabs, either beach sand was used or the water was chloride rich (say brought from nearby backwaters?), etc. A piece of spalled concrete can be analysed for chloride content - if more than 0.15% by wt of concrete, corrective actions must be taken.
The only way to stop issues with  chloride contaminated concrete is to stop 100%  moisture and oxygen ingress  into the concrete, after repairing the spalls. There are excellent solutions that are affordable; other methods such as Electrostatic chloride extraction are too expensive and impracticable in an occupied flat.
Hope the above helps.




On Tue, May 17, 2022, 9:47 PM nitbehl77 forum@sefindia.org (forum@sefindia.org))> wrote:

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[vikram.jeet]

With passage of time,, but in contact with moisture / seepage,, The reinforcement bars get corroded ans exert pressure on concrete cover chipping it off underside of affected slabs.

First aid to this is to chip off affected slab area from underside,, clean it with wire brush to clean rusting as possible,,
Weld  chicken mesh ( thin dia ) and  Apply a coat of epoxy adhesive prior to plastering And Rich coarse sand plaster be applied. Final finish using putty.

For Reduced strength,, it is advisable to support slab using square pipe hollow section ( at least 150*150 , but as per strength requirements)  -  two nos ,, so that span of slab us reduced. Sq hollow sections do not pose aesthetic issues, but provision of structural steel members provide new life to structure.