Cement Coping: 2 x 4 Marks in the dried coping: how to remove them?

[Curlenjik]

The manufacturer of my new cement coping for my kidney shaped pool refuses to stand behind his product. 2 x4 marks have shown themselves as the coping was delivered and installed - that were not there three months ago. They are marks of where the coping had been stacked upon 2 x 4's and are now IN the cement.

Any suggestions of how to get them out?
a. I have had one coping piece ground down - and the marks come out - but the coping is now smooth and has to be acid etched all over again so as not to be slippery.
b. Someone suggest having each piece sandblasted.

Also white alkali has repeatedly come up on the surface of each cement piece. Sometimes it dries and upon the next rain disappears. Any ideas of how to remove the alkali or prevent it from appearing?

[PoolDoc]

Hi Curl;

I've replied by email, but here's what it said:


Send me some pictures to this email address -- as a large and detailed as you can -- and I'll edit and post them.

Also, include manufacture info on the coping, and photos (if you have them) of the coping uninstalled, showing the reverse sides. I assume these are cement based, cast coping?

Do you have pool water test results AND fill water tests? If not, get the best results you can, including metals info. Fill water metal info is available from your water supplier, if you are on a public system.

Also, info about any sort of "mineral device", 'magnet', or other treatment gizmo is essential AND a list of chemicals you've been using.

Sorry, I've been inattentive to the forum. Besides the forum, I've had some ongoing serious issues in my extended family that have been a black hole for time.

[Curlenjik]

I sent you a reply from my e-mail,. And I also sent the pictures of the coping. These are new coping pieces and were installed as you can see when there was NO water in the pool. The pool plaster itself has been demolished. I cannot go further and replaster the pool until I resolve the coping question.

(Pictures from email added by PoolDoc)

1.
https://lh6.googleusercontent.com/-TWDLRcie1L8/TwNA_e79vVI/AAAAAAAAApE/VxODFhtFW3s/s1024/x-a_004.jpg

2.
https://lh5.googleusercontent.com/-flMSE0vgQvk/TwNBACl9-xI/AAAAAAAAApY/W-2hPJuk09U/s1024/x-a_005.jpg

3.
https://lh5.googleusercontent.com/-lrJcC0yDDBI/TwNA_4Sy5bI/AAAAAAAAApU/s51CBidUgSs/s1024/x-a_006.jpg

4.
https://lh6.googleusercontent.com/-evUdw4u7VLY/TwNBALlyWwI/AAAAAAAAApk/xldMa6_x1vo/s1024/x-a_018.jpg

5.
https://lh5.googleusercontent.com/-NBzAZdgI-Zw/TwNA_XGAzSI/AAAAAAAAApI/xqd4fQHn-RI/s1024/x-a_008.jpg

[PoolDoc]

Others may know more, but it looks like a *light* acid wash AFTER the pool is full and the deck has been grouted, would remove those marks.

But, time will probably remove them, too, and with less damage to the coping surface.

Also -- and I'm guessing -- I think most concrete product suppliers would consider such storage marks 'normal'. They will (usually) weather away, and trying to avoid them may well be hard. High end decorative products may be handled in such a way to avoid such marks, but then you have to pay the big $$$'s. I doubt you'll find plain cast concrete handled that way.

I'd really encourage you to wait till the end of a season before resorting to an acid wash. But, I would NOT put a 'sealer' on the coping or deck castings, till the marks are gone

[Curlenjik]

Thanks for your advice.

The guys who installed the coping already tried to get those marks out -- they did a very light acid wash -- and nothing happened - you see them as they were.

On a separate test piece I tried TSP and that did not work - stained the piece even worse.

So you suggest:

1. Grout the coping
2. Put in the expansion joint between the coping and the deck pavers (which are in sand)
3. Use the pool for a season - even though the coping shows the alkalie marks as well after they are wet.
4. At the end of the season, then do a light acid wash again.

Is that about it?

Again, thanks for posting and for your advice.

[PoolDoc]

I'm not sure I'm ready to elevate my guesses to a full-blown suggestion.

I've seen marks like those 'age out' of concrete, but I don't have ANY understanding of exactly what causes those marks (I mean chemically; I know how to 'make' them), and I don't have the sort of experience that would allow me to say that what I've seen happen elsewhere, will happen to your pool.

If you can wait, wait. See if you get another answer from someone with more experience and more confidence in their answer.

I don't know if there's some sort of concrete forum on the Net; if there is, you might want to post there, because marks like these aren't unique to pools. You can use the links to the photos here. Since I put them on Picasa, it's not costing me anything for someone to download a meg's worth of image files.

If you do find an answer elsewhere, post it back here, if you don't mind.

[Curlenjik]

Will do and thanks again; if you hear of anything new, please pass it on to me. I'll read this column for the next couple of weeks, and again I thank you for taking the time to reach out and help.

S.

[PoolDoc]

Unless you have disabled that feature in your profile, you should automatically receive emails, any time someone posts to this thread.

[Curlenjik]

My contractor had one spare coping piece sandblasted and that WORKED! So I am going to have the entire coping around the pool sandblasted and then stained to keep the alkalie from leeching through. Thanks for helping me noodle this problem.

[Curlenjik]

After sandblasting new concrete coping, what is the best sealer? A Lithium Sealer which is supposed to last 30 years, or a good sealer that lasts for 2-4 years. Is a Lithium Sealer good for Southern California outdoor, in the ground pool coping?