Constantly wet concrete

[lunct]

Hi,

What would happen to constantly wet concrete like the column or beam of exposed parts of the building that is not been waterproof for years?

 

[Ron]

Some calcium compound leaching, possible rebar corrosion, but generally ok for concrete to be wet.

 

[lunct]

For a concrete gutter that is not waterproof with the rainwater just flowing out of a hole in the concrete. The concrete won't get soft even after decades? What happens if there is severe calcium compound leaching after decades?

I'm asking because many old buildings have concrete gutter without waterproof and I'm just wondering what happens.. i'm not building a new one which of course I'll apply waterproof.. thanks..

 

[hokie66]

While concrete is not impervious, it does not allow leakage of copious amounts of water unless it is cracked. If your gutters have cracks, they will leak. The concrete won't "get soft", but it could be subject to spalling if the reinforcement corrodes. There are a number of reasons for reinforcement corrosion...one common one is carbonation, which results in the alkalinity of the concrete being reduced to the level where the steel is not protected from the atmospheric conditions.

 

[JAE]

Some of the concrete areas will get much higher compressive strength - that's a lot of wet curing!

Check out Eng-Tips Forum's Policies here:
faq731-376

 

[lunct]

Some of the concrete areas will get much higher compressive strength - that's a lot of wet curing!

Oh.. which reminds me to ask this question.. some old houses have foundations with water always running around them.. what usually happens to such foundations that is always wet?

 

[Lomarandil]

Perhaps it would be useful to think of it this way .. Do they build docks and piers out of concrete? (Yes)

----
The name is a long story -- just call me Lo.

 

[IRstuff]

And even seawalls and dams.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

http://www.eng-tips.com/forumlist.cfm

 

[JAE]

...and dam spillways, concrete drain pipe, wastewater and fresh water tanks....

Check out Eng-Tips Forum's Policies here:
faq731-376

 

[lunct]

...and dam spillways, concrete drain pipe, wastewater and fresh water tanks....

But won't the dams constant wetness results in, as hokie put it "the alkalinity of the concrete being reduced to the level where the steel is not protected from the atmospheric conditions".. this should cause dams rebars to corrode and all dams fail at certain time.. doesn't it.. you mean not all constant wetness results in alkalinity decrease? What cause alkalinity decrease then?

 

[MotorCity]

Corrosion occurs quicker in steel that is exposed to the atmosphere with wetting and drying cycles than steel that is continuously submerged. This is because you need oxygen for corrosion to occur. Steel exposed to the atmosphere has more exposure to oxygen than constantly submerged steel which only has the dissolved oxygen in the water.

 

[hokie66]

Reduction of alkalinity by carbonation occurs due to exposure to air, not water. Just Google "carbonation of concrete".

 

[lunct]

uhm... for foundations underneath the soil.. is there air enough to cause reduction of alkalinity by carbonation (that should occur due to exposure to air)?

 

[OldBldgGuy]

Maybe we should tell the precast guys to stop building & selling tanks & pipes & culverts & etc.? It didn't occur to us that they would stay wet...