Refractory Mortar: Yes, it does like to take the brick with it when you dismantle, and that was after only two days. Do not ask me why I can confirm this during the build stage.
- Cast-refractory heat risers using perlite aggregate, or other methods to create insulation value, various thickness (1" to 2" have been successful in short-term prototypes but long-term data not available).
Has anyone used Geopolymers, specifically Low-Temperature Geopolymer Setting (LTGS), for the construction of their rocket stove? Any short term or long term data?
I am building a small j-tube 6" rocket stove with a 4.5" x 9" x 18" burn tunnel to heat riser ratio (1-2-4) as a prototype. The box portion will be cast with LTGS. The riser portion will be made from "Kiln Brick".
The curing is done initially at ambient room temperatures. Then a solar curing box can be used.
The wall thicknesses will vary from 1 1/2" to 2 1/2".
The main ingredients of the LTGS are:
sodium water glass powder
very fine slag sand
a very small amount of portland cement
I obtained the ingredients for the firebox mentioned above for about $30.
Glenn Herbert wrote:I checked the specs and the customer Q&A at Lowe's, and these are not "concrete" as the title says, but standard firebrick. The 3000 degree spec is contradicted by an answer in the Q&A that says they are good for 2000-2300 degrees, which is good enough if not spectacular. 3000 degree firebrick are a specialty high-performance item, not likely to be standard at a consumer big box store. Kiln supply companies offer 2300 degree and 2600 degree firebricks, with the 2600 version distinctly more expensive.
The upshot is that this would be a typical material for a J-tube and heat riser. You might want full thickness firebrick (4 1/2" x 9" x 2 1/2") for the bridge over the burn tunnel, as that shape might be more durable than the equivalent in splits on edge; I haven't seen comparison tests there.
I am building a j tube rocket stove and saw this Lowes fire brick as well. I did not find the 2000/2300f rating. But if its suitable its easy for me to get and no shipping. Can you explain what you mean by full thickness bricks. or splits? much appreciated