Post by Karl playing with geopolymers on Dec 9, 2017 8:07:54 GMT -8
Professor Davidovits has obviously never realized the real potential of the LTGS technique. In another patent he tries to deny his LTGS patent as prior art During the next few days, I will use a brush to coat the Rocket-Forn made from old tobacco cans with a zeolite-based LTGS geopolymer blend.
One only needs to add a few percent short fibers to the mixture to prevent drying cracks. If you ever wanted to realize a crazy design, which would be impossible with bricks or plain casting, that may be the way to go.
Post by Karl playing with geopolymers on Dec 10, 2017 6:54:25 GMT -8
Geopolymers are inorganic resins and therefore can be processed like other pourable and spreadable polymer resins. Youtube houses a huge amount of examples of processing fiber reinforced plastic.
More than 40 years ago, I have professionally built molds for prototypes with resins. For headlamp housings, enclosures for air conditioners, amature parts and so on in the automotive field.
In Germany, prices for basalt fiber are similar as for glass fiber. Short basalt fiber can be mixed in. Basalt fiber fleece, needled basalt fiber mats or other basalt fabrics can be soaked with geopolymer resin.
Of course one can use more expensive ceramic fiber products as well.
What are you using here as a "binder"? Clinoptilolite as in the link or something else? If it is clinoptilolite, please comment on his water demand & drying-shrinking. Less then bentonite? More then kaolin?
Please comment that the mould-s shud be kept at (more or less) constant temperature-no thermal dilation and no moisture generating. It is difficult for some people to have a hobby room constantly heated at winter.
Post by Karl playing with geopolymers on Dec 13, 2017 6:24:27 GMT -8
Clinoptilolite is used as binder and as aggregate. Currently my cellar has about 12°C/54°F. Pure clinoptilolite hardens even at such low temperatures just slower.
Clinoptilolite requires less water and shrinks less than clays. The water demand and & drying-shrinking depends on the particle size. Some larger particles as aggregate reduce the water demand, let it dry faster and reduce shrinking a bit, but make it more brittle.
Post by coastalrocketeer on Dec 14, 2017 23:00:59 GMT -8
What is your process in terms of timing, how to stir or blend the mix with the water, judging the amount of water in the mix, etc?
What I have done so far with lye and the SweetPDZ powder at 20g lye to 60g Zeolite (1/3 ratio) for binder cured too fast at the elevated temps that I was experimenting with, so trying my next batch at room temp...
Even mixing another experimental ratio at room temp, I noticed a point when the mix definitely grew thicker and increased in thixotropic quality to the point where it would not be applicable with a brush.
Do I need more water? (Used 20g, same as the lye)
Is this change in viscosity/thixotropic response the point when it's ready to mix in the aggregate portion? Too late?
Can curing be enhanced/accelerated by heating to say 170F, after the aggregate is mixed in, or is this prone to make mold expansion/contraction an issue?
Post by Karl playing with geopolymers on Dec 15, 2017 5:39:24 GMT -8
For making a binder without an external heat source the chemical and heat produced by it must be as concentrated as possible. I do not add all water at once but much smaller amounts several times, while stirring the mixture to take maximum advantage of concentrated chemical and heat.
The thickening comes partially from the reduction of the particles and from the onset of gelation.
Once the paste got very thick some more water can be added.
With an external source of heat slightly more water can be used from the beginning.
The excess of lye in the binder speeds up particle reduction and gelation, but delays hardening. A binder with a low mineral to lye ratio will remain water soluble even after it got hard.
In the final mixture the binder will reduce the attackable particles of the other ingredients and gel them. Both can be improved by additional heat and the final hardening as well.
The final mixture should not contain more water than required for the task.
Post by Karl playing with geopolymers on Dec 16, 2017 8:53:57 GMT -8
Aside of temperature proper curing and curing time also depends on lye concentration. More water reduces lye concentration and thus may require more lye and not to forget it also extends drying time. Therefore a mixture should not contain more water than required for the task. Castable mixtures should contain just enough water to flow under vibration.
During the warm seasons pure zeolite can be demolded after about 24 hours and will have reached most of it's final strength after about one week. A mixture half zeolite half clay takes usualy twice as long, but depending on the clay it can take even longer.
At the current12°C/54°F in my cellar it takes at least twice as long.
Post by Karl playing with geopolymers on Dec 31, 2017 12:10:26 GMT -8
Since by far, most of the heat is reflected the extreme insulation of the small core makes it practically impossible to get the short riser hot enough to sustain draft. At the start the rather soft wood I have got does not deliver enough heat energy to get it going.
Even bringing it into a vertical position so that the flames could get easily up and touch the walls of the riser did not get in hot enough. Back in a horizontal position for measuring the temperature in the riser the IR thermometer showed less than 50°C/122°F.
I had no problems with similar dimensioned cook stoves on the Philippines which were made from less insulating clay, by using similar wood.
Today is the first dry and not to windy day since the core got hard and dry.
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deadstarsstillburn: but I do not need to heat all of it by any means. probably only need to heat half of that, maybe less.
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