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LECA (Lightweight Expanded Clay Aggregate) for insulation Hearth - Forno Bravo Forum: The Wood-Fired Oven Community

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LECA (Lightweight Expanded Clay Aggregate) for insulation Hearth

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  • LECA (Lightweight Expanded Clay Aggregate) for insulation Hearth

    Does anybody out there have any experience with using LECA (Lightweight Expanded Clay Aggregate) - aka Lytag as an insulant?

    I'm wondering whether it could be substitued for Vermiculite / perlite in the Concrete Insulation Hearth mix...

    Seems to me that it would provide a much more rigid load-bearing platform for the insulating hearth than the 'cork-like' vermivulite/perlite mix...?

  • #2
    Re: LECA (Lightweight Expanded Clay Aggregate) for insulation Hearth

    I think this is a new one on us. From this page:
    Although light expanded clay aggregate is typically more expensive then the other popular grow media - such as rockwool, coconut fiber or perlite and vermiculite - clay aggregate pellets are one of the only growing medium that can be cleaned and reused repeatedly after each hydroponic growing season.
    I don't think you need to worry about the compressive strength of vermiculite (or perlite) concrete. They make swimming pools out of it, and they support tons of water.

    But to answer your question, I'm sure it would work fine.
    My geodesic oven project: part 1, part 2

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    • #3
      Re: LECA (Lightweight Expanded Clay Aggregate) for insulation Hearth

      Hi,
      Im new ,first , thanks for this great information.

      I want to know if the LECA is used in the same proportion like perlite or vermiculite.

      Thanks a lot.

      Comment


      • #4
        Re: LECA (Lightweight Expanded Clay Aggregate) for insulation Hearth

        Hi thanks for the help

        How much will be the proportions to make an insulate lightweight pre-cast framework 2" to 2 1/2 " thick wall with sand , portland, Leca and lime, with around 3/8 rebar 4.2 mm ( thick rebar make this crack ).

        I thinking to used mortar type N and add 2 parts Leca, thats correct.?

        Also I can sustitute Leca for perlite, vermiculite , to have the same results (insulate lightwheigt concrete )

        Thanks for the help the idea is make something easy to move.

        Walt

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        • #5
          Re: LECA (Lightweight Expanded Clay Aggregate) for insulation Hearth

          Hi,
          if of interest i use expanded Clay quit often for my ovens.
          loose or mixed with firecement depending what i want to achieve.
          Its very pleasant to work with no dustmask or gloves required and over here in europe its much cheaper than vermiculite or perlite. its main use is as a bedding for roadconstrution and they need a lot of it. i get it in tonne bags.

          hope that helped a little
          cheers

          Comment


          • #6
            Re: LECA (Lightweight Expanded Clay Aggregate) for insulation Hearth

            thanks, I already use the lecca, is very good, the oven is a lot more light easy to move, here in USA is not cheap...

            thanks

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            • #7
              Re: LECA (Lightweight Expanded Clay Aggregate) for insulation Hearth

              Originally posted by waltiti View Post
              thanks, I already use the lecca, is very good, the oven is a lot more light easy to move, here in USA is not cheap...

              thanks
              I'm so pleased to hear that there is at least one part of the oven that is cheaper here in Europe, everything else, especially the bricks, seems to be double the price here (Sweden) vs USA.
              Let's keep it metric

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              • #8
                Re: LECA (Lightweight Expanded Clay Aggregate) for insulation Hearth

                I've used LECA and found it pretty good stuff. It is stronger than vermiculite or perlite and therefore makes a stronger product when combined with cement, but as it is denser, is not as good an insulator. It is also about double the cost, by volume, for me at least. There can be a slight problem with it during placement as it tends to want to float to the surface. I found that wetting it down first so each little ball absorbs some moisture will prevent this. If you have an application where you particularly want strength it is a good aggregate to use. I get mine from hydroponics suppliers.
                Kindled with zeal and fired with passion.

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                • #9
                  Re: LECA (Lightweight Expanded Clay Aggregate) for insulation Hearth

                  It's all over the place here, cost depends on volume but it's about half of vermiculite.
                  15$ for 45 litres or 100$ for a cubic metre (leca). Vermiculite at the store goes for just over 50$ per 100 litres.
                  Let's keep it metric

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                  • #10
                    Re: LECA (Lightweight Expanded Clay Aggregate) for insulation Hearth

                    It is much better to use in lightweight concrete, but not so much for insulating concrete. It is better than nothing though, so go for it.

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                    • #11
                      Re: LECA (Lightweight Expanded Clay Aggregate) for insulation Hearth

                      I will use it for my (first?) oven. Most of the material is salvaged from demolition or building sites so I feel no need to pay 200$ for the ceramic fibre board.
                      My plan is to make a mold out of 2x3" or 2x4", probably 2x4" an pour the mix in it. I want it only to be as large as the oven and not to protrude but how is that made?
                      Of course with an exact mold but that is tricky with the circular shape transitioning into the landing.

                      What if I make it octagonal and just let the insulation cover the worst and let stucco cover the rest? Maybe it'll work.
                      Let's keep it metric

                      Comment


                      • #12
                        Re: LECA (Lightweight Expanded Clay Aggregate) for insulation Hearth

                        Make it larger then cut it away.

                        Comment


                        • #13
                          Re: LECA (Lightweight Expanded Clay Aggregate) for insulation Hearth

                          OK so should I place a sheet of plastic film underneath so it wont stick to the concrete slab? Guess that's a good idea, then I could "easily" cut it to shape with an angle grinder or reciprocating saw.
                          Let's keep it metric

                          Comment


                          • #14
                            Re: LECA (Lightweight Expanded Clay Aggregate) for insulation Hearth

                            If you are going to surround your hearth insulation pour then these pics show one way to do that. You can then pour your insulating layer inside the form. It is an idea to have a drainage hole under the insulating material (I used vermicrete) in case your hearth gets wet in the future.
                            Attached Files
                            Cheers ......... Steve

                            Build Thread http://www.fornobravo.com/forum/f3/n...erg-19151.html

                            Build Pics http://www.facebook.com/media/set/?s...1&l=1626b3f4f4

                            Forno Food Pics https://www.facebook.com/media/set/?...1&l=1d5ce2a275

                            Comment


                            • #15
                              Re: LECA (Lightweight Expanded Clay Aggregate) for insulation Hearth

                              I will probably make a circular shaped mold of 0.9 mm sheet metal and fill it, then an outer mold of 2x4" for the landing/vent area. My foundation is kind of massive concrete so it will be hard to make a decent drain. I will just have to cover the whole thing with stucco and live with a slightly higher-than-normal igloo =)

                              EDIT: just realizing that my signature dont rhyme to well with "2x4"
                              Last edited by ugnsnisse; 05-07-2014, 10:40 AM.
                              Let's keep it metric

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