Rust seepage from surround

[cmooty]

So I have a concrete surround on the pool. In a few areas either above the water line, or on the horizontal part of the coping, there are rust stains. I'm guessing this is coming from regarding in the concrete. Pictures below. Any thoughts on how to deal with this?

 

[kimkats]

You could try crushing cheap vitamin C tabs (ascorbic acid) in a sock and set it on the stain for a few minutes. You might need to wet it down since this is not in the water. Let me know what you see after you do this.

Kim

 

[duraleigh]

It sure looks like rust. How was that coping formed? Was it poured concrete and then plaster on top?

 

[HiddenRiver]

I think the word “-regarding-” in original post was supposed to be “-rebar”-? Just love that auto-correct spelling. It looks like the rust is coming from within the concrete (from steel rebar -concrete reinforcing bars) and working its way out to the surface. My husband is a structural engineer and i have heard this before. During the curing process of the concrete usually there are little cracks that form. As moisture (and especially salt) gets in to these cracks the rebar rusts and expands resulting in more cracking of the concrete. In bridges now (since the 60’s) the rebar is epoxy coated or galvanized——-these will only rust if there is a nick in the coating. A possibility anyway

 

[cmooty]

It sure looks like rust. How was that coping formed? Was it poured concrete and then plaster on top?

I'm not sure, pool came with house.

 

[cmooty]

I think the word “-regarding-” in original post was supposed to be “-rebar”-? Just love that auto-correct spelling. It looks like the rust is coming from within the concrete (from steel rebar -concrete reinforcing bars) and working its way out to the surface. My husband is a structural engineer and i have heard this before. During the curing process of the concrete usually there are little cracks that form. As moisture (and especially salt) gets in to these cracks the rebar rusts and expands resulting in more cracking of the concrete. In bridges now (since the 60’s) the rebar is epoxy coated or galvanized——-these will only rust if there is a nick in the coating. A possibility anyway

Sounds right, any thoughts on further prevention?