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Thread: Gunite Cure time?

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    Gunite Cure time?

    Hey all,
    Quick question on gunite. I've heard from someone that gunite should cure 30 days before plaster. My PB is definitely NOT on that schedule. He's moving much faster. I see lots of pools built here in TFP in less than 60 days, so it seems like if a 30 day cure was required, I'd have heard about it. I suspect my 'source' is wrong, but I thought I'd bounce the idea here for feedback.

    Thanks!
    34x17 Freeform Gunite IGP and spa (approx 17k gal)
    Hayward 2HP/2SP TriStar Filter Pump & Tristar Booster
    ProLogic PS-8 and AquaPod
    400k Heater
    CLI Sunstone Quartz Plaster

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    Re: Gunite Cure time?

    http://www.cement.org/basics/concretebasics_faqs.asp

    What does 28 -day strength mean?

    Concrete hardens and gains strength as it hydrates. The hydration process continues over a long period of time. It happens rapidly at first and slows down as time goes by. To measure the ultimate strength of concrete would require a wait of several years. This would be impractical, so a time period of 28 days was selected by specification writing authorities as the age that all concrete should be tested. At this age, a substantial percentage of the hydration has taken place.

    What is 3,000 pound concrete?

    It is concrete that is strong enough to carry a compressive stress of 3,000 psi (20.7 MPa) at 28 days. Concrete may be specified at other strengths as well. Conventional concrete has strengths of 7,000 psi or less; concrete with strengths between 7,000 and 14,500 psi is considered high-strength concrete.

    Up to you and PB on how long you want it to sit. Keep in mind that the concrete is curing in that 30 days, whether the PB is doing other things around it or not.

    My PB said to keep it wet (water it 4 to 5 times/day) for 14 days. It's still curing after 14 days but the water doesn't penetrate as much and now the curing is going on inside under the hardened outer parts.
    ~TexSS Built: 8/13, 19K Gal ?, IG Pebble, 3 HP IntelliFlo XF Pump, 100 Sq. Ft Pentair Quad D.E. Cartridge Style Filter, Chlorine, Cleaner Pentair Legend
    Geometric Pool Size 24 x 26 513 Square Feet; Perimeter - 107; Depth 3 x 5 1/2 x 4
    100 Sq. Ft Pentair Quad D.E. Cartridge Style Filter; System Pump Pentair 3 HP IntelliFlo XF; Water Feature Pump Pentair 2 HP Whisperflo; Pentair EasyTouch 8 Automated Control System, with IntelliChlor and Wireless Remote Control; ScreenLogic 2; Heater - 400,000 BTU Pentair MasterTemp; Cleaner Pentair Legend; 2 Pentair Intellibrite 5g Color LED Pool Lights & Pentair Intellibrite 5g Color LED Spa Light; Nysa Travertine Coping; Honey Gold Classic Split Faced Wall Stone; Pebble Sheen - Aqua Blue; Walnut Tumbled Travertine Decking atop 4 Poured Concrete Decking

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    Re: Gunite Cure time?

    Tex$$,

    Thanks for that very informative and easy to understand response.
    Dave S.
    42k vinyl and concrete pool, 1.5hp pump, 140gpm filter
    TFTestkits , PoolMath , Pool School

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    Re: Gunite Cure time?

    This site has a good graph if you are more visual person.

    http://www.cement.org/tech/cct_curing.asp
    ~TexSS Built: 8/13, 19K Gal ?, IG Pebble, 3 HP IntelliFlo XF Pump, 100 Sq. Ft Pentair Quad D.E. Cartridge Style Filter, Chlorine, Cleaner Pentair Legend
    Geometric Pool Size 24 x 26 513 Square Feet; Perimeter - 107; Depth 3 x 5 1/2 x 4
    100 Sq. Ft Pentair Quad D.E. Cartridge Style Filter; System Pump Pentair 3 HP IntelliFlo XF; Water Feature Pump Pentair 2 HP Whisperflo; Pentair EasyTouch 8 Automated Control System, with IntelliChlor and Wireless Remote Control; ScreenLogic 2; Heater - 400,000 BTU Pentair MasterTemp; Cleaner Pentair Legend; 2 Pentair Intellibrite 5g Color LED Pool Lights & Pentair Intellibrite 5g Color LED Spa Light; Nysa Travertine Coping; Honey Gold Classic Split Faced Wall Stone; Pebble Sheen - Aqua Blue; Walnut Tumbled Travertine Decking atop 4 Poured Concrete Decking

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    Re: Gunite Cure time?

    Given, those charts, I wouldn't think it would take very long at all for the concrete to become hard enough to handle water. The pressure at the bottom of an 8' pool is less than 4 PSI which is less than 0.03 MPa so there is very little load on the concrete. That load level isn't even discernible on the charts and much less than 7 days.
    Mark
    Hydraulics 101; Pump Ed 101; Pump/Pool Spreadsheets; Pump Run Time Study; DIY Acid Dosing; DIY Cover Roller
    18'x36' 20k plaster, MaxFlo SP2303VSP, Aqualogic PS8 SWCG, 420 sq-ft Cartridge, Solar, 6 jet spa, 1 HP jet pump, 400k BTU NG Heater

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    Re: Gunite Cure time?

    Thanks for all the replies and info! Very educational! I also spoke to a gunite company and between what I learned there and here, I definitely think a 5-7 day cure for gunite is adequate for construction to continue. This is a great forum! Thanks again!
    34x17 Freeform Gunite IGP and spa (approx 17k gal)
    Hayward 2HP/2SP TriStar Filter Pump & Tristar Booster
    ProLogic PS-8 and AquaPod
    400k Heater
    CLI Sunstone Quartz Plaster

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    Re: Gunite Cure time?

    Did you see this article referenced in another posting today? I assume you are in a high heat/low humidity place.

    http://www.poolgeniusnetwork.com/pro...gPost%3A476085
    -- Guy --
    10K gallons in 21' Round 52 inch wall Aqualeader AG, Hayward Power Flow LX 1.5 HP pump motor, Hayward Perflex EC50AC DE filter w/Cellulose, Wide mouth skimmer, 2013 new Diver Dan (craigslist) to replace the faded old Hayward AquaBug. TF-100

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    Re: Gunite Cure time?

    Quote Originally Posted by techguy
    Did you see this article referenced in another posting today? I assume you are in a high heat/low humidity place.

    http://www.poolgeniusnetwork.com/pro...gPost%3A476085
    I didn't see it. Thanks for pointing it out! I'm not sure how I'll get around the heat/humidity issue. I need to read that article more thoroughly (only time to skim it so far) Maybe I can put a misting house around the yard on plastering day!?
    34x17 Freeform Gunite IGP and spa (approx 17k gal)
    Hayward 2HP/2SP TriStar Filter Pump & Tristar Booster
    ProLogic PS-8 and AquaPod
    400k Heater
    CLI Sunstone Quartz Plaster

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    Re: Gunite Cure time?

    IIRC, they said one thing to do was to tent the pool during plastering and add humidity. I am sure the workers will like that!

    Is your humidity high or low there.
    -- Guy --
    10K gallons in 21' Round 52 inch wall Aqualeader AG, Hayward Power Flow LX 1.5 HP pump motor, Hayward Perflex EC50AC DE filter w/Cellulose, Wide mouth skimmer, 2013 new Diver Dan (craigslist) to replace the faded old Hayward AquaBug. TF-100

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    Re: Gunite Cure time?

    Sometimes its high, sometimes low. Around 30 percent lately

    34x17 Freeform Gunite IGP and spa (approx 17k gal)
    Hayward 2HP/2SP TriStar Filter Pump & Tristar Booster
    ProLogic PS-8 and AquaPod
    400k Heater
    CLI Sunstone Quartz Plaster

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    Re: Gunite Cure time?

    IIRC, 30 was an OK range but I assume (incorrectly possibly) that tenting and cooling the work area with some water could improve the curing process of the plaster.

    This is all assuming the article is accurate.
    -- Guy --
    10K gallons in 21' Round 52 inch wall Aqualeader AG, Hayward Power Flow LX 1.5 HP pump motor, Hayward Perflex EC50AC DE filter w/Cellulose, Wide mouth skimmer, 2013 new Diver Dan (craigslist) to replace the faded old Hayward AquaBug. TF-100

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    Re: Gunite Cure time?

    Quote Originally Posted by techguy
    IIRC, 30 was an OK range but I assume (incorrectly possibly) that tenting and cooling the work area with some water could improve the curing process of the plaster.

    This is all assuming the article is accurate.
    Well, it's something I can look into, so thanks for pointing it out! Yeah, I'm sure the workers would LOVE a humidity tent.
    34x17 Freeform Gunite IGP and spa (approx 17k gal)
    Hayward 2HP/2SP TriStar Filter Pump & Tristar Booster
    ProLogic PS-8 and AquaPod
    400k Heater
    CLI Sunstone Quartz Plaster

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    Re: Gunite Cure time?

    There are numerous tower cranes around Austin and I can promise you they are not waiting 28-days to go vertical. Gunite is porous, the plaster seals everything up. I expect you will have plaster the week before labor day.
    +/-16k gallon IG pebblesheen pool with SWG, spa and waterfall, Hayward 2HP 2-speed Tri-star, Hayward 1.5HP Tri-star, Hayward 5030 Cartridge filter, Hayward H400 Heater, Sharkvac Robotic Cleaner

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    Re: Gunite Cure time?

    Quote Originally Posted by TAMC93
    There are numerous tower cranes around Austin and I can promise you they are not waiting 28-days to go vertical. Gunite is porous, the plaster seals everything up. I expect you will have plaster the week before labor day.
    I hope so! I think we'll be shooting gunite this week assuming we get these little issues taken care of early in the week. I'm ready!
    34x17 Freeform Gunite IGP and spa (approx 17k gal)
    Hayward 2HP/2SP TriStar Filter Pump & Tristar Booster
    ProLogic PS-8 and AquaPod
    400k Heater
    CLI Sunstone Quartz Plaster

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