Hello Everyone & THANK YOU !! Ok this is my first post but I've been lurking for a long time . I just wanted to drop a line on this last experiment wave & see if maybe I'm destin for failure or on the right track of somthin new . I Hate buying new much as us all, so I started playing with some old gypsum board as an insulating material alternative to refractory & thus far it is awesome .
Light weight , excellent insulator , & I've found that if you chunk it & beat it like mash potato's you can pour it , form it & use it to patch, glue & what not . It seems to be holding up to the heat really well . So as I mentioned earlier I've been on here awhile & consider my self well read on this & have had several test fires with different types of stoves .  BUT I have yet to read or see any mention of this material as an application .  So feed back would be GREAT .  Thank you all once again & I look forward to your wisdom .........P.s Currently working on a new multi fuel rocket mass heater .. 2 barres side by side the 2nd is part of the mass With the firts having a semi standard rocket feed BUT the first barrel has a large gasket w/ opening in the top & a drop down baffle, Here's the cool part ..IF I remove the lid and also remove  the heat riser I am able to place one of several burn baskets & the rocket becomes the intake . So far this has allowed me to burn saw dust pre packaged in a can , coal, on a grate , & many other riged up fuel cells .......   So once again Input PLEASE !!!

Morning , Working on pics as we speak . I'm more handy than computer savy so I'll check back after the weekend & try to post some pic's & video.  Were rebuilding a unit in the basement presently so hopefully all goes well . This is version # 7 hope its lucky !

I am surprised that dry wall material would stand up to the heat without getting weak and crumbling. Part of my background is designing and building high temperature equipment using different refractories. I do not consider either plaster or portland cement to hold up to temps approaching 1000 F. By the time you get either of these up around 800 F they start to re-calcinate and loose their cast strength. either that or the residue water in them turns to steam and causes spauling.
kent

Some of this was gleaned  from old postings in which I explain how to get free gypsum and the experiments I've conducted with this material.

    Houses built before 1980 often have ASBESTOS drywall tape and mud, so don't get your material from houses this old.

    Many heating systems which use heated water under the floor prescribe the use of gypsum covering the pipes since it is good at radiating heat and it has a  high heat capacity (.26 as compared to .2 for cob).  This material is commonly purchased in bags just like cement and lime are packaged. It costs seven dollars for a 40 pound bag.

   Now the free part. Actually it's much better than free! Used a drywall is made of gypsum and depending on where you live can cost anywhere from $100-$200 per ton for disposal. Where I live in Victoria BC I charge $200 per ton for the removal of this material. Find a drywaller and become his disposal guy and make at least $100 per pickup load.


                          EXPERIMENTS

    Using a small children's pool I soaked some of this material and then ran it through a bearcat garden chipper. The resulting paste was somewhat chunky but very easily troweled and there is no reason why this could not replace purchased gypsum. I will use more than 10 tons of this material as soundproofing and as thermal mass adjacent to my RMH. Houses built before 1980 often have asbestos drywall tape so don't get your material from houses this old.


         I ran several strength tests on gypsum which I pulverized in the garden chipper. I made several hockey puck sized pancakes of this material and allowed them to dry. With some I stripped the paper off and pulverized only the gypsum and then mixed half of this batch with 10% Portland cement and the others I just allowed to dry without additives.

     The one with Portland required maybe 20 pounds pressure to break with a twist of the wrist. The one without Portland required less than half as much strength and it crumbled.

    Next I ran some gypsum through the chipper paper and all. Again one batch of pancakes was mixed with 10% Portland cement and the other was just allowed to dry. The one with Portland cement and paper was so strong I couldn't break it with my hands. The one with just paper broke with a hard twist of the wrist and was probably twice as strong as the sample with Portland cement but no paper.

    So for most purposes drywall can simply be run through a hog with paper attached and a relatively strong and malleable paste results. This product is not sticky enough to use on its own as a finishing plaster but it would certainly work for filling cavities anywhere in a house where you're looking for thermal mass and soundproofing.

    Since all paper is covered in gypsum these cakes were fireproof. 

      Running gypsum through any sort of chopping device while dry is asking for a dust storm and would also wear out your equipment faster. The dampened material made no dust and it ran quieter than when chipping branches. Restricting the outflow allows for a very fine grind but for most purposes you're simply looking for lots of easily spreadable material so the stuff could be run through rather quickly.

    IMPORTANT NOTE: although the resulting material looks a lot like concrete it is highly absorbent and completely unsuited for any exterior application. Even the cakes with 10% Portland cement become soft and breakable when wet.

   I've conducted experiments on several other readily available materials and will post a separate thread concerning the results. I have a pretty good understanding of scientific method and although I'm a mad scientist, I'm only mad at waste and inefficiency . Thank you: Dale

Hi ALL, Well all is goin well with the new stove SO FAR . I'll be interested is finding the post on dry wall & other materials that was mentioned .
The dry wall experiment is Real close to what I've been doing & one thing I have found is that adding a little more fiber to the mix makes the bricks hold together a little stronger also  . I don't have the name in front of me & have a total mental block but it's sold in bags & used specifically for concrete . ALSO when used in the burn chamber it's not lasting very long, about 10 burns & if bumped falls apart.  It's defiantly working better in the riser where it is just a filler along with the ash thats in there .  Pictures soon, even shot some video...........