lawry
Junior Member
Posts: 113 
|
Post by lawry on Aug 18, 2016 7:09:36 GMT -8
With regard to your clinoptilolite casting...what is "milked" clinoptilolite or is it a typo and supposed to read "milled"? Did you mix it with anything else? Sorry about that. Yes I meant "milled". I used it like I would use Fly Ash. |
|
lawry
Junior Member
Posts: 113
|
Post by lawry on Aug 18, 2016 7:15:14 GMT -8
But problem is that the inside part of the firebox doesn't wanna come out. Did you made the form obliquely ? I am guessing you are asking if I made the form with the draw angle included.? No I didn't. |
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Aug 18, 2016 7:43:41 GMT -8
I'd need Karl to confirm, but i thought that micronized clinoptilolote was supposed to be used in the same "mix" that Karl had defined using micronized perlite (45% micronized perlite, 45% clay, 10% lime/hydrated lime...%'s by weight). To this mixture you add enough sodium silicate to make it the consistancy of cream and then add aggregate if you choose. This mixture works for me, though commercial waterglass may need some additional lye. Indeed with clinoptilolite the mixture with lime or cement starts faster geling than with perlite and may need a retarder (table sugar) to keep it liquid for some time. However complete curing takes longer. For a mixture that can take more aggregate two parts zeolite and one part clay works better. From the fine slag sand (0.09-0.25 mm) it can take up to four times the weight of the zeolite. Above the 4/1 ratio the resulting geopolymer concrete starts to become brittle, but depending on the use more may be possible. The 4/1 slag sand/zeolite mixture takes very long time to cure under ambient conditions. I would recommend curing at 50°C for a few hours, then the temperature can be raised to about 75°C for some time more. BTW my geopolymerisation experiment with 250 mesh feldspar worked out well. Relatively soft metamorphous rocks like shale, shist and slate could be milled with a cascading ball mill. The hardness of shale, shist and slate is similar to clinoptilolite. |
|
lawry
Junior Member
Posts: 113
|
Post by lawry on Aug 18, 2016 9:06:39 GMT -8
I will try that mix. I was getting worried that the bag will go to waste.
Karl do you have some pics of the feldspar experiment? It's great for reference.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Aug 18, 2016 13:15:08 GMT -8
|
|
|
|
Post by firewatcher on Aug 18, 2016 15:25:54 GMT -8
Here's a quick update on my latest trial mix...I molded a 5 inch diameter 3 inch thick "puck" last night. It must be drying too fast though as there are some significant cracks in it after only 24 hours of dry time.  I used the 45% micronized perlite / 45% fire clay / 10% hydrated lime recipe. To give a complete recipe mix, to that i added 2 cups of home made sodium silicate (550g silica gel / 450g NaOH / 2L water mix)...mixed it all together...then added 3 cups of the aggricultural grade perlite as aggregate and rammed it into the 5 inch diameter 3 inch tall "mold". When putting it into the mold, it WAS a little bit liquidy (probably didn't actually need to ram it into the mold...maybe could have vibrated it in just fine). |
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Aug 18, 2016 16:32:09 GMT -8
firewatcherThere is no real need to add perlite as aggregate. It weakens the structure and makes it prone to cracks. Even with fine sand (preferably an aluminosilicate, which may contain other metal oxides) a geopolymer can have a low thermal contuctivity. Here I have explained why. donkey32.proboards.com/thread/2053/selecting-aggregates-geopolymer-castablesAs such a geopolymer can get very strong it does not need to be very thick, thus can have a relatively low mass.
|
|
|
|
Post by firewatcher on Aug 18, 2016 17:23:10 GMT -8
Karl,
So, to clarify, no aggregate is necessary...but if you choose to use one only a very fine (prefferably aluminosilicate) variety is recommended?
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Aug 19, 2016 5:06:22 GMT -8
Yes, no aggregate is necessary...but geopolymers made from pozzolans with a high water demand, like metakaolin or micronized zeolites need very careful curing and drying without fine sand and are prone to micro cracks at high temperatures. Natural or waste aluminosilicates contain other metal oxides creating a mixture of many minerals with a lot of grain boundaries and thus do not carry heat very well. The darker colored a natural silicate sand the more likely it is an aluminosilicate of volcanic origin, containing other metal oxides. www.google.de/search?q=volcanic+sand&biw=1750&bih=878&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwijmK-JwM3OAhWC2BoKHTVtDJgQsAQIKgwww.sandatlas.org/volcanic-sand/Not to forget money matters for many. Here in Germany I can get get 25Kg sacks of grog for about 1€ or less per Kg, shipping icluded. Natural zeolite is not expensive too. A whole metric tonn of grog, if one wants to cast a complete stove, starts at around 200€ plus shipping. In the UK metakaolin is not expensive and granulated blast furnace slag quite cheap. Even in the US, depending on the location, one may not be able to save much money by adding aggregates for a fire box. |
|
|
|
Post by ronyon on Aug 19, 2016 19:40:56 GMT -8
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Aug 20, 2016 4:07:52 GMT -8
Yes, the slag sand I have used is coal slag abrasives.
Slag from metal extraction could be used too.
Water cooled slag would be the best choice, as it is amorphous.
Air cooled slag crystallizes.
The density should be less than 3g/cm³.
Very heavy slag could cause segregration and would raise the mass.
Even small amounts of crushed glass can be used.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Aug 20, 2016 8:54:21 GMT -8
I have made another "reverse side test". This time I have throwed a lot more heat energy against another 17mm thick geopolymer concrete plate. s61.photobucket.com/user/geo-karl/media/ReverseSideTest_zps73mnxmmt.jpg.html?sort=3&o=0The plate is made of 50 micron clinoptilolite, ball clay 1/3 bei weigt of the zeolite, slag/zeolite ratio 4/1, 10% low purity pottasium hydroxide, some citric acid as an accelerator and 330g/liter solid content waterglass made from formsil 113 (granulated solid sodium waterglass). The cured plate was heated to 250°C to get rid of all the water including the water bonded to the large inner surface. The density is about 1.45, which indicates that rougly 40% of the volume is air enclosed in very small pores invisible to human eyes. The slag sand has no pores,
thus quite obviously the binder fulfills the requirement for an aerogel with at least 50% porosity
The area touched by the flame of the gas torch has a diameter of about 6cm, 3cm glowing hot. Temperature difference to the hot spot on the other side was about 800°C. Everybody who tries to beat this by adding perlite, vermiculite , saw dust and what ever else,
will significantly weaken the structure and to compensate for the weakness likely end with significantly more mass.
The brown color of the pieces in the background comes from sugar used as retarder as the pieces were heated to 250°C. By accident I have made a video without noticing it. Most of it does not show anything. I have no experience in video editing and no tools installed. |
|
lawry
Junior Member
Posts: 113
|
Post by lawry on Aug 22, 2016 12:25:19 GMT -8
Looks more or less like ordinary concrete. Yup it looks like concrete. thanks for the pics. Firewatcher the balls you are using in your mill, are they specifically for milling? Is the inside of your drum modified in anyway to assist the milling? |
|
|
|
Post by firewatcher on Aug 22, 2016 12:52:02 GMT -8
Looks more or less like ordinary concrete. Yup it looks like concrete. thanks for the pics. Firewatcher the balls you are using in your mill, are they specifically for milling? Is the inside of your drum modified in anyway to assist the milling? No the milling media i'm using was another "free-b"...they are just roller bearings that i was lucky enough to get for no money. By tomorrow I'll post a couple more pictures of the media and a video that i promised to make of it in operation. Tapatalk isn't allowing me to attach these things at the moment (keeps crashing when i try) so I'll have to transfer the video and such from my phone to the old computer and do it that way. |
|
|
|
Post by firewatcher on Aug 22, 2016 13:52:20 GMT -8
Yup it looks like concrete. thanks for the pics. Firewatcher the balls you are using in your mill, are they specifically for milling? Is the inside of your drum modified in anyway to assist the milling? OK...I had a few minutes...thought that I'd better post the pics now.
![]()
This is the "milling media" and a pic of the inside of the mill (I'm going to need to find a way to reduce the size of the video...I keep getting an error saying that the file is too big:
So here are the pictures of the "milling media" that I'm using and a pic of the inside of the drum:   |
|
