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Thread: Shotcrete versus Gunite

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    Shotcrete versus Gunite

    We're getting quotes for a new IG pool about 20'x40' and some are proposing shotcrete and others gunite. The shotcrete bids are coming in about $20K higher than the gunite bids. Any opinions on which is "better" or what I should consider?

    Thanks!

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    JoyfulNoise's Avatar
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    Shotcrete versus Gunite

    They are basically the same thing. Look it up on Wikipedia. I believe shotcrete is the general name for the process and "gunite" is an actual trademarked name. The only difference in the overall process is if they do the shotcrete wet out of the nozzle or if the do it it dry and mix water in at the nozzle. I believe gunite specifically refers to a dry mix being pneumatically pumped out and mixed with water after the nozzle.

    They should produce the same end result and there should be no difference in price. Something sounds fishy.
    Matt
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    Re: Shotcrete versus Gunite

    Shotcrete has the advantage of having larger aggregate in the mix and the yields are typically higher in compressive strength given the same precured cement content. Some may also argue that more pneumatical force can be be applied to Shotcrete during application yet still produce minimal rebound.

    All things considered in a swimming pool, either option will produce a strong shell. The skill and knowledge of the applicator and crew will far supercede any negligible differences between the two.

    If you talk to a gunite guy, he'll say gunite is best. If you talk to a Shotcrete guy, he'll say Shotcrete is best. Truth be told, once set up to do gunite or Shotcrete, a switch to the other would be very expensive and require purchasing new equipment.

    I don't see how the bids are 20k higher for Shotcrete. In my experience in my area, gunite is running $10/yard more than Shotcrete right now.
    -Brian-
    33K In ground Pool/Spa, IntelliFlo, IntelliChlor SWG, Easytouch, ScreenLogic, MasterTemp 400, Quad 100, IntelliPH, MiniPebble, Dolphin Z5, POOL BUILD
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    Re: Shotcrete versus Gunite

    In my situation, since I am OB, I chose a company that does both. They guarantee lifetime warrantee on the shell for either product and told me it was my choice, as both are the same PSI strength in the end. I told them they could choose which they would like to use, since both were the same price, and they were the ones warranting the work. They chose Gunite. In talking to the guys that were applying it, they liked gunite a bit more because they felt that they could control the mix better, since it was being done at the nozzle, rather than premixed and shot out.. So, I would ultimately go with the less expensive solution in your case, since the end result is supposed to be the same.
    Cement Pond <--- build - 15K gal, 16 x 34 Rectangle, All Pentair - 520 Filter, 2 Intelliflo 2VST pumps (3hp) - 1 filter/1 water features, EasyTouch 8, Screen Logic, IC60 SWG,
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    Re: Shotcrete versus Gunite

    That's a strength and weakness for both.

    From my perspective, I can order the Shotcrete and specify the cement, aggregate, and water content (slump) which are then measured by a computer and generate a ticket that shows each of those parameters and the batch mix time so I know how long it's been in the truck. Once the truck arrives, I'll look into the barrel and then pour a couple slugs that can later be tested to confirm I got what I paid for. On very hot days, plasticizers can be added to replace/reduce the water needed for application without decreasing the ultimate cured strength.

    Gunite is much different. I prefer to have the mix brought dry in a cement truck for the same reasons mentioned above but not all contractors do this. There are a couple contractors near me that dump sand in the street and shuttle it to their equipment with a skip loader where it is then mixed with cement and carried to the nozzle by compressed air. In this scenario the cement/sand ratio is nothing more than an approximate, as is the water/cement ratio as the nozzle applicator controls it basically by sight. The finishers prefer a wetter mix because it's easier to trowel and smooth but this yields a much weaker product that is prone to shrinkage cracks and reduced compressive strength.

    I don't want to sound biased in one way or another but my experiences make me lean toward Shotcrete; part of that has to do with very bad experiences with a local ready mix company.

    Barring a quality and knowledgeable contractor, either product will be a fine choice.

    My pool is Shotcrete and I built my neighbor's with gunite... Both are still holding water
    -Brian-
    33K In ground Pool/Spa, IntelliFlo, IntelliChlor SWG, Easytouch, ScreenLogic, MasterTemp 400, Quad 100, IntelliPH, MiniPebble, Dolphin Z5, POOL BUILD
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    Re: Shotcrete versus Gunite

    I'm going to generally agree with BriAn here. I will add that in Sacramento the gunite generally comes from a national supplier that runs mix trucks and generally delivers a consistent product.

    But in the end you end up with results that are indistinguishable.
    22k gallon IG pebblefina, Jandy 1.5 HP VS, Jandy CV Cartridge filter, Fafco solar panels, Polaris 360 supply side cleaner, waterfall

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    Re: Shotcrete versus Gunite

    One more interesting thing, you can take it for what its worth. I was talking with my plasterer about the difference, and he stated that he would rather plaster Gunite over Shotcrete. His reasons were (1) the plaster bonds much better to Gunite, in his experience, and (2) He says that generally Gunite is smoother with less bulges, etc. more fodder I guess...lol
    Cement Pond <--- build - 15K gal, 16 x 34 Rectangle, All Pentair - 520 Filter, 2 Intelliflo 2VST pumps (3hp) - 1 filter/1 water features, EasyTouch 8, Screen Logic, IC60 SWG,
    Pop-up Cleaners (Wet Deck and steps), 2 LED Bubblers, 3 LED 24" waterfalls, 5G LED Pool Light, Quartscapes Reflections Tahoe Blue plaster, Real Coral coping/deck, TF-100 Test Kit, 1766 Salt test kit.

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    Re: Shotcrete versus Gunite

    Thanks for the great feedback - we're going with Gunite

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    Re: Shotcrete versus Gunite

    Looking at your location on an island it may be the simple fact that one is mixed dry on site and the other is delivered wet on a cement truck
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    Re: Shotcrete versus Gunite

    Quote Originally Posted by daddymack View Post
    One more interesting thing, you can take it for what its worth. I was talking with my plasterer about the difference, and he stated that he would rather plaster Gunite over Shotcrete. His reasons were (1) the plaster bonds much better to Gunite, in his experience, and (2) He says that generally Gunite is smoother with less bulges, etc. more fodder I guess...lol
    If I was a plaster contractor, I'd prefer gunite too. A smoother surface means less plaster material and an easier job.

    Shotcrete is very rough compared to gunite. I don't see how any cementious material would bond better to a smoother surface but I guess the contractor's experience will far outweigh mine.
    -Brian-
    33K In ground Pool/Spa, IntelliFlo, IntelliChlor SWG, Easytouch, ScreenLogic, MasterTemp 400, Quad 100, IntelliPH, MiniPebble, Dolphin Z5, POOL BUILD
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    Re: Shotcrete versus Gunite

    Quote Originally Posted by bdavis466 View Post
    If I was a plaster contractor, I'd prefer gunite too. A smoother surface means less plaster material and an easier job.

    Shotcrete is very rough compared to gunite. I don't see how any cementious material would bond better to a smoother surface but I guess the contractor's experience will far outweigh mine.
    The Surface is more even (less bulges, etc). Maybe smoother was a poor choice of words..
    Cement Pond <--- build - 15K gal, 16 x 34 Rectangle, All Pentair - 520 Filter, 2 Intelliflo 2VST pumps (3hp) - 1 filter/1 water features, EasyTouch 8, Screen Logic, IC60 SWG,
    Pop-up Cleaners (Wet Deck and steps), 2 LED Bubblers, 3 LED 24" waterfalls, 5G LED Pool Light, Quartscapes Reflections Tahoe Blue plaster, Real Coral coping/deck, TF-100 Test Kit, 1766 Salt test kit.

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    Re: Shotcrete versus Gunite

    Shotcrete would theoretically provide a better mechanical bond for plaster to adhere to because of the roughness of the aggregate.

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    Re: Shotcrete versus Gunite

    Quote Originally Posted by DBfan187 View Post
    Shotcrete would theoretically provide a better mechanical bond for plaster to adhere to because of the roughness of the aggregate.
    I absolutely agree
    -Brian-
    33K In ground Pool/Spa, IntelliFlo, IntelliChlor SWG, Easytouch, ScreenLogic, MasterTemp 400, Quad 100, IntelliPH, MiniPebble, Dolphin Z5, POOL BUILD
    Davis Custom Construction - Home Page @daviscustomconstruction

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    Shotcrete versus Gunite

    We had 4 pool bids and one of 4 was a gunite shell. We went with the PB who quoted us shotcrete and yes it was rough but I felt the Pebble finish would adhere better.


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