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How strong can you make perlite? - Forno Bravo Forum: The Wood-Fired Oven Community



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How strong can you make perlite?

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  • How strong can you make perlite?

    I want to put a perlite top over 4" of 1" CF blanket....I don't need it for insulation. I'd like to fashion it in a tall hip roof configuration,think French ranch house. To be covered with approx. 1-2" of stucco type mortar and possibly using a cobble design roller or stamp. There is 9 courses of brick surrounding the oven with 2 1/2" of loose vermiculite between the oven and the 4" CF layer. Just about 10" sticks out above the surrounding wall...this will be where the perlcrete will be used. Can lime be used with the perlcrete? What type cement will give me a harder perlcrete? Repeating......not using the perlcrete for insulation.....The pictures don't show it ,but, there are 9 courses of brick surrounding the oven... The box around the oven is complete, just need the top....and the archway floor...p.s. the oven cleared in a hour with a armfull of white oak...kept it there for an additional hour,cooked pork roast, squash and potatoes, shut UN insulated door....30 hrs. later, still in the 300's..............whooohoooo.
    Last edited by thickstrings; 06-19-2013, 12:01 PM. Reason: addition
    " Life is art, live a masterpiece"

  • #2
    Re: How strong can you make perlite?

    You can make up a standard 3,2,1 aggregate, sand, cement concrete mix and use the perlite as the aggregate. This produces a fairly strong result, but reduces the insulating capacity. If you want it even stronger then make the aggregate portion of the mix 50% perlite 50% standard aggregate. Be aware that perlite takes up a large amount of water that you need to eliminate later.
    I've just got a sample of expanded clay which is an aerated clay about the size of peas. It is about double the weight of perlite , but quite strong. I'm thinking of using the stuff in an application where strength is required. The trouble is that it is also around double the price of perlite.
    Last edited by david s; 06-19-2013, 01:37 PM.
    Kindled with zeal and fired with passion.


    • #3
      Re: How strong can you make perlite?

      We have a product over here called Maximizer that uses expanded shale as an aggregate. It is tested to 5500PSI, but is a little tricky to use. The beauty is that the 80# bag = 1 CuFt whereas a normal 80# bag would cover .66 CuFt.

      Expanded shale by it's nature and manufacture is extremely dry and absorbent. It will flash set in about 40 seconds if you do not use pretty much the full dose of water to start.

      Perlite can be used to make lightweight concrete as noted above.


      • #4
        Re: How strong can you make perlite?

        Originally posted by Tscarborough View Post
        "but is a little tricky to use. ".

        "It will flash set in about 40 seconds if you do not use pretty much the full dose of water to start.
        Is that the understatement of the week!!!!

        Flashes in 40 seconds sounds like something I will avoid like some guys avoid their X-girlfriends.


        • #5
          Re: How strong can you make perlite?

          It is not a problem in a mixer, jut when mixing by hand.