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Post by gadget on May 19, 2018 19:42:23 GMT -8
Ok, karl and sksshel you got me thinking about geopolymer and I have come up with a crazy idea after doing some reading. I was thinking about using some steel slag as my storage mass and found this article; www.sciencedirect.com/science/article/pii/S1687404816300219It talks about making a geopolymer with steel slag. here is a chemical analysis of steel slag; www.slg.jp/e/slag/character.htmlTypical primary ingredient in sleet slag is limestone. I can get slag by the truck load for pennies a few miles from my house. People use it here all the time as a driveway base because it is so cheap. It is also very heavy and has lots of mass. I'm still learning about geopolymer so I don't know for sure if it is a go or not with slag. I am hoping for a cob like material using a geopolymer turned slag to form the heating mass. It would be much easier then trying to contain a heating mass with packed slag in a large container. -Gadget |
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Post by Deleted on May 20, 2018 6:01:48 GMT -8
Chemical reactions of insoluble or only slightly soluble minerals in wet state require a very large surface.
The Blaine value is a standard measure of the degree of fine grinding of cement.
It is given as a specific surface area (cm2 / g) determined in the laboratory using the Blaine device.
Standard portland cement CEM I 32.5 has a Blaine value of approximately 3,000 to 3,500. The diameter can vary between less than 1 μ up to approximately 100 μ. For a Blaine value of 3000-3500, an average particle size of 6.3 μ to 5.4 μ is needed.
For chemical reactions amorphous particles are much better than crystalline.
Your slag must be amorphous with about 200 mesh, or you can use it only as aggregate
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Post by gadget on May 20, 2018 6:30:22 GMT -8
Chemical reactions of insoluble or only slightly soluble minerals in wet state require a very large surface.
The Blaine value is a standard measure of the degree of fine grinding of cement.
It is given as a specific surface area (cm2 / g) determined in the laboratory using the Blaine device.
Standard portland cement CEM I 32.5 has a Blaine value of approximately 3,000 to 3,500. The diameter can vary between less than 1 μ up to approximately 100 μ. For a Blaine value of 3000-3500, an average particle size of 6.3 μ to 5.4 μ is needed.
For chemical reactions amorphous particles are much better than crystalline.
Your slag must be amorphous with about 200 mesh, or you can use it only as aggregate
Yes, this is where my knowledge is limited. I know they sell it in various configurations. Fairly fine all the way up to inches in diameter. My coworker did a parking spot with a road base from fines to small rock size. I don't know how fine though. I'm guessing this is where the flyash I see in recipes come in to play. I will have to check and see exactly what they sell. If they sell flyash it might not be as cheap as the slag. They practically give the slag away for free. Most of cost is just to deliver it. Probably would be free if I picked it up myself. Its kinda like horse manure, they are always making more. I was initially thinking that it would make a great aggregate for mass heat storage due to its density. This stuff is heavy. Packed tightly into a strong (steel?) container forming the mass shape and surrounding the flue pipe. But if it could be formulated into a cement like state, then there could be a bell design vs a pipe type design with what I would think had a large heat storage capacity more then cob. -Gadget |
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Post by drooster on May 20, 2018 14:10:50 GMT -8
Great for mass,
but even finely ground not great for refractory ingredient.
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Post by Deleted on May 21, 2018 5:11:30 GMT -8
Great for mass, but even finely ground not great for refractory ingredient. Why? Could you please enlighten us ?
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Post by keithturtle on May 21, 2018 22:53:38 GMT -8
I don't know either, but every bag of castable I've used is certainly not uniform, mostly variations in perlite size as far as I can tell. Most firebricks exhibit some sort of randomness as well
Turtle
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Post by pianomark on May 22, 2018 4:49:24 GMT -8
Gadget,
I am inclined to think that you could make a "cob like material" by substituting the slag for the sand fraction in a traditional cob mix. That would increase the density and heat storage of a given volume of the resulting cob. It might work fine where straight cob is traditionally used, such as a heat storage bench with imbedded pipe. If you want a bell rather than a piped bench, you could cover horizontal half barrels with the heavier slag-cob. Lots of examples elsewhere on this forum. Or you could try making adobe bricks from the slag-cob and building the bell with them (maybe some other material to support the roof of the bell). In either case, lots of needed testing of materials and mixtures for stength, heat resistance, etc.
I don't know how much extra mass/heat storage it would create, so can't say if it justifies all the extra work. However if you like to "tinker" with stuff, then it may not feel like work. And the research helps those who follow...
Good luck.
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Post by Deleted on May 22, 2018 6:26:26 GMT -8
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Post by drooster on May 22, 2018 12:49:24 GMT -8
Great for mass, but even finely ground not great for refractory ingredient. I seem to have been caught lying. It is GREAT for refractories. Maybe. Your turn Karl. Did you put a riser on your car-body-filler mockup? |
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Post by keithturtle on May 22, 2018 22:55:38 GMT -8
Great for mass, but even finely ground not great for refractory ingredient. I seem to have been caught lying. It is GREAT for refractories. Maybe. Your turn Karl. Did you put a riser on your car-body-filler mockup? Easy now folks... |
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Post by Vortex on May 23, 2018 1:21:46 GMT -8
I don't know either, but every bag of castable I've used is certainly not uniform, mostly variations in perlite size as far as I can tell. Most firebricks exhibit some sort of randomness as well Turtle Keith, I've never heard of castable with perlite in it, did you mean grog? |
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Post by keithturtle on May 24, 2018 10:10:23 GMT -8
I don't know either, but every bag of castable I've used is certainly not uniform, mostly variations in perlite size as far as I can tell. Most firebricks exhibit some sort of randomness as well Turtle Keith, I've never heard of castable with perlite in it, did you mean grog? Yes, I wasn't sure what it was, must be grog. |
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Post by branja on May 25, 2018 23:05:49 GMT -8
To increase surface, reduce particle size. Make a ball mill. Mine cosded about 10usd. Takes around a liter of material. I got nice stuff from plain roof tiles(that stuff is extremly chemicaly inert,it is baked on 900+ Celsius). You can even copy sceintific papers 1:1 with grounded slag.
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Post by gadget on May 28, 2018 21:33:45 GMT -8
To increase surface, reduce particle size. Make a ball mill. Mine cosded about 10usd. Takes around a liter of material. I got nice stuff from plain roof tiles(that stuff is extremly chemicaly inert,it is baked on 900+ Celsius). You can even copy sceintific papers 1:1 with grounded slag. Hey Branja, I've been thinking about building one. It gets old real quick breaking grog down by hand. -Gadget |
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Post by gadget on May 28, 2018 21:39:36 GMT -8
Great for mass, but even finely ground not great for refractory ingredient. I took a torch to some slag I "borrowed" from a drive way today. It melted to glass fairly easily. It became more brittle the more I heated it. Some pieces cracked after heating. Very crumbly after firing. Much weaker then before heated. I'm not seeing much bonding from heating other then going to very weak glass. So....drooster appears to be correct...not the best refractory material. -Gadget |
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