Very long hairline cracks shotcrete shell

[austinpoolcool]

Hi, I want to say thank you before I start. I entered contract with my current PB last Nov before I found TFP. There are many things I wish I had known before entering this contract, but I tell myself better now than later! I really appreciate the amount of information and knowledge that is available to all on this website.
My PB shot my shell four weeks ago. My house is built on limestone and contractor overdug by a foot so backfilled using gavel to bring it up to the contracted height.
Two weeks ago, I noticed two very long hairline cracks on my pool. Notified my PB and they offered to chisel out and fill with hydraulic cement (not done yet), but today I am seeing cracks have become very slightly wider and additional cracks formed in cross shape around the main drain.
Now they are hairline cracks, but the length and the fact they go up all the way up the wall keep me up at night. Should I be calling in a structural engineer at this point? Any advice is much appreciated. Thank you

 

[kimkats]

Hi and welcome to TFP. I am sorry to be meeting this way.

Do you have pictures of the rebar part of the build?

Have you been watering the shell? If not please start doing so now.

It is very common for concrete to crack. In fact it is more common for it to crack than to not crack.

Saying that I understand why you are worried. I would not be too worried if your rebar was done correctly. I think it is just drying too fast and as such cracked.

 

[AQUA~HOLICS]

What was the process used for compaction of the gravel to bring the elevation to the required height?

 

[ajw22]

Welcome to TFP.

Do you have any pics of the dig and rebar before gunite?

Did you water the gunite for a week or so after it was shot?

 

[austinpoolcool]

Thank you for replying. PB said gravel is self compacting, and I don’t remember any heavy equipment coming in for compaction. I don’t have any photos after full dig, but here are half-way dug and rebar:

I also watered four times a day for the first two weeks

 

[poolmagazine]

The cracks themselves look fairly superficial and not out of the ordinary. Sealing and prepping the substrate should be done before plaster. To answer your question, it's quite common and some cracks actually reseal themselves as the cement continues to hydrate underwater.

 

[kimkats]

It looks like your steel work is good. Nice and tight as it should be. You should keep watering your shell. This heat has been brutal so I would keep it watered.

 

[SwimmingBevo]

The heat is brutal in Texas. We poured last Tuesday until evening and I’ve had soaker hoses on my beam around entire pool and spa non-stop. Engineers said to keep it that way for two weeks minimum with the sun landing on us. Curing is a critical step to strong concrete.

Found this link on TFP: Finding the Cure - Water Shapes

Your pool does look ok from what I’ve had in previous pools. I had thicker crack just as long if not longer that never showed up after plaster when properly sealed prior.

Double check they used fly ash in their shotcrete. I’m building my second pool because my first shotcrete pool in Texas didn’t contain it and had to be ripped out. Was / still is a nightmare. Started breaking down year three. Hundreds of cases in central Texas. My new pool is gunite.

 

[sktn77a]

Notify the PB in writing of the cracks and your concern and get a response in writing. He's going to say "it's fine and normal". It may well be, but if you have any issues down the road, you'll have this documentation.