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Post by smarty on Sept 7, 2014 3:54:00 GMT -8
Found a guy selling zeolite for £25 per 25kg bag just round the corner from me its 2mm-5mm size grains. I can't find any cheaper than that and I've tried cat-litter and aquarium as well as soil conditioner searches.
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Post by photoman290 on Sept 7, 2014 4:35:18 GMT -8
i conly find the 07-1.6mm zeolite at rsminerals. smarty if you want some to try let me know.
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Post by Deleted on Sept 7, 2014 5:33:55 GMT -8
UK members have some options to save money
GGBFS (ground granulated blast furnace slag) 25kg ~ £6 Fuel ash 25kg ~ £8.50
Melting point of both above 1200°C and will increase by geopolymerisation.
Argical M 1000 25kg ~ £14
Argical (or other highly reactive metakaolins) needs some other pozzolans anyway to get higher strength.
For example 75kg mixture ~ £29
Chopped hemp 200L (20kg) ~ £13 About 0.5 -1% of the dry weight are enough to let water escape.
BTW I have just mixed metakolin with fly ash, which is with respect to curing time a very good mixture. GGBFS will make the mixture denser.
GGBFS can be fine or like sand.
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Post by Deleted on Sept 7, 2014 8:56:18 GMT -8
The piece of metastar with homemade waterglass did not survive forced drying at 90°C and cracked.
Commercial waterglass tends to crack with low density mixtures too, even at ambient temperatures.
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Post by smarty on Sept 8, 2014 2:49:22 GMT -8
i conly find the 07-1.6mm zeolite at rsminerals. smarty if you want some to try let me know. I take it then that it has to be finer particles from the stuff I found?
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Post by smarty on Sept 8, 2014 2:58:04 GMT -8
The piece of metastar with homemade waterglass did not survive forced drying at 90°C and cracked. Commercial waterglass tends to crack with low density mixtures too, even at ambient temperatures. I was just thinking of trying to make some homemade potassium silicate out of the gone off colloidal silica I have. Again I came to realise how I don't understand the chemistry of all this. Apparently according to Davidovits the optimum safe - i.e. merely irritant MR for potassium silicate is 1.85 SiO2:1 K2O but since I am mixing Si with KOH I have no idea how to work out the ratio of ingredients. I assume that when mixed they combine to form SiO2 and K2O but how do I work out what the proportion of initial ingredients should be to get a target ratio of 1.85?
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Post by Deleted on Sept 8, 2014 4:20:49 GMT -8
smarty you can save yourself the headaches with waterglass. So far I have not found any convincing reason to use waterglass, but lots against. Waterglass is only needed to create extremely tight geopolymers, with virtually no pores, for extremely high compressive strength. Extremely tight geopolymer structures will have problems at very high temperatures, among others causing a breakdown of compressive strength. It is better to start with lower compressive strength, but remain stronger or even gain strength at very high temperatures. Preparing parts of some denser pozzolans like grog or molochite with 20% NaOH/KOH powder to partly dissolve them gives good results for mixtures of lower density and is safer than extremely caustic mixtures with waterglass. You will see the results once you have got my samples.
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Post by photoman290 on Sept 8, 2014 4:43:29 GMT -8
like smarty i am not entirely sure what is going on with the crystal lattice structure of geopolymers,even after watching hours of davidiots telling me about them! but the light is beginning to dawn slowly. most of the papers i have looked at have been aimed at comparing geopolymers to portland cement for compressive strength,this is a totally different application to the one we are trying to create. karls last post sums it up nicely for me.
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Post by DCish on Sept 8, 2014 5:04:30 GMT -8
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Post by Deleted on Sept 8, 2014 5:30:18 GMT -8
My experiments are for rather liquid castable mixtures with high to low density, but for making bricks compacting is common practice.
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Post by smarty on Sept 8, 2014 6:22:55 GMT -8
I take karl's point about the high compressive strength not being suitable for our purposes but the only thing is I was looking at the possibility of laminating using geopolymers which I imagined being a little like organic resins in consistency and where the density is not an issue since the section is so thin.
Another requirement is that it sets up - at least to a gel stage at room temperature in a workable timescale, say a pot-life of 1/2hr and an initial set of no more than 1hr. My tendency has been, thus far, to go down the potassium silicate route based partly on what I have read and partly on the feel of the stuff when you use it. It just seems resin like.
Karl do you think that an impregnating resin can be made using no water-glass perhaps using silica fume or fly-ash? Would this get rigid enough in such thin sections, and could it set in the right timescale at room temperature.
The reason why I like the idea of laminating is that it is lightweight, strong, and can be backed up with a variety of different density/insulative layers that could just be rendered on over the top of the basic laminated shape. laminating also gets out of having to make complicated moulds. All that you need is a shape of the inner- negative section of the thing you are making which could be as simple as a few blocks of 4x2" wood screwed to a board to make each half. Trip wires, syphons, ridged roof to the burn tunnel all these things become easy-peasy. It opens up so many more design principles and would be great for fast manufacture of prototype designs.
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Post by Deleted on Sept 8, 2014 7:37:14 GMT -8
smarty, yes an impregnating resin can be made using no water-glass. For laminating a bit more NaOH/KOH is required. Argical, grog or molochite can be mixed with NaOH/KOH in advance, one or more days. There will be a partial disolution and geling, but else not much will happen without an starter/accelerator like lime. Not tested with KOH, but I cannot see why there should be a difference. Fly ash connot be premixed as it contains lime. Baking powder works as an accelerator too, but I have not tested if it alone would be enough. Baking powder can also be used to adjust viscosity. Very little is neded. Once the accelerator is added the polymerisation process can start. You need to prevent the laminate from drying out, as the chemical process requires water as a media.
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Post by photoman290 on Sept 8, 2014 10:03:40 GMT -8
so if i understand this correctly,you can make a low viscosity paste and laminate glass mat with it for the layer onto the mold,then when that has cured you could add some more grog to the the same viscosity mixture to add some thermal insulation?
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Post by DCish on Sept 8, 2014 13:38:50 GMT -8
Karl, will KOH and natural clay also be sped up by addition of lime (guessing it should... Unless there is something about "grogging" the clay that makes a difference)
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Post by Deleted on Sept 9, 2014 2:54:10 GMT -8
Yes, KOH and natural clay will also be speed up by addition of lime. However, the effect will be much weaker, because natural clay is chemically quite inert.
For faster results a small amount of a pozzolan like fine grog is also required. Instead a small amount of a ready mixture of lime and pozzolan AKA ordinary cement can be used. In this way it is possible to make castable mixtures of natural clay hardening at ambient temperatures.
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