Multiple rebar rust stains in 9 year old plaster pool - seeking permanent fix

[Slange]

Each prior rust stain has been drilled out and patched, but new ones keep popping up in different areas of the pool. Once known rust stains are properly repaired, will replastering or adding pebbletec prevent further rebar rust stains from appearing? Or will more major work need to be done to fix my recurring problem?

Background:
About 4 years ago I posted on this forum about a rebar rust stain in my then 5 year old pool. The pool builder wonderfully accepted responsibility and repaired the spot at no charge (i.e., drained pool, drilled out the rusted rebar, patched, refilled pool). I paid for the refill water and startup chemicals, but was happy to do so. The pool builder acknowledged the problem is caused by rebar/ties being too close to the plaster surface.

In the past 4 years, 3 more rebar rust spots have appeared in different areas of the pool, and the pool builder gladly repaired them. I must say this is amazing, given the pool is now 9 years old and the most recent drill-out patch job was done last week. Can't say enough good things about my pool builder.

Well, I just checked the pool this morning, and yet another rebar rust stain has just appeared :-(

At 9 years, I assume I am now at the end of the lifespan of the plaster and that I will now/soon need to re-plaster or add pebbletec? With so many rebar rust issues, what needs to be done to fix the problem? Will a normal pebbletec/plaster job fix the recurring issue?

Cheers!

Pics for reference of a couple of the prior spots.

 

[Jimrahbe]

Slang,

Are you sure they are rust stains? Are they flush with the plaster surface or are they raised well above the plaster??

Let's see if @onBalance has any input.

Thanks,

Jim R.

 

[Slange]

Thanks for your reply. Yes, they have all been rebar rust stains. I believe they have all been flush. The repair man has shown me the rebar that he drilled out and removed.

 

[onBalance]

Yes, that is rebar rust that is bleeding through the plaster to cause the orange/brown stains.
It is unfortunate that is happening, and it is a 50/50 situation on whether a re-plaster job would prevent further rust bleeds.
And there is no guarantee that the rust bleeds won't continue. However, it has been nine years, and there is a chance that further rust stains may not occur. Sorry I don't have a better answer for you. Btw, plaster finishes can last up to 25 years.

 

[ajw22]

I think all you can do is play wack-a-mole with the rust stains and cut them out as they pop up.

Maybe you have got all the rebar ties close to the surface, maybe not. You just don't know.

 

[Slange]

Thanks for the replies.

Further clarifying question - assuming there are other spots where rebar/ties are close to the surface, would adding new pebbletec somehow seal the surface to prevent further spots from rusting? Or is this a potential issue no matter whether the pool is refinished or not?

One person I talked to seemed to claim that pebbletec would form a barrier that would prevent further rusting out. But that refinishing with plaster would not form the same barrier, and the spots could keep coming.

 

[onBalance]

Not true. No difference between pebble and typical white cement plaster. Pebble finishes still use cement as the binder.

 

[blakeusa]

The problem is that the rebar is not embedded enough in the gunite/ concrete shell. Its possible that they did not shoot enough gunite over the bottom to fully cover and encase the rebar. Even if your plaster was really thick the plaster would suck out the rust from the concrete shell... So new plaster on top may be subject to the same issues. What I might suggest is that you talk to your pool builder *if you are going to replaster to maybe add a few inches of new gunite on top of your existing shell before plastering. This would involve proper prepping of the old surface and using a bonding agent to stick the old to the new. Then plaster on top of the new thicker surface. Is it only on the floor? and not on any walls? Just my 2 cents.

 

[Slange]

Thanks @ajw22, @onBalance and @blakeusa! Very helpful insights, and good to now know that just adding pebbletec won't 100% stop further rebar rust spots.

The rebar rust spots have been in several spots around the pool, including on the sides. Sounds like to really fix the issue, we'll need to add some gunite all over the pool. Or just continue to play whack-a-mole To be honest, I don't really mind the optics of the repairs, even though they don't totally match the original finish.

I'll talk to the pool builder about a plan forward. Thanks again everyone for your help, very much appreciated.