Steve Shelton wrote:
Satamax Antone wrote:Fill with concrete. Sand insulates.
Another alternative would be to fill them with Cob. I have plenty of sand and clay on hand.
Graham Chiu wrote:Very nice. How are you distributing the heat to the rest of the house?
Steve Shelton wrote:A few suggestions:
- make the roof of your firebox several inches thick. Geopolymer needs to be cured by fire to reach full tensile strength.
- metal rods can be imbedded into the geopolymer to help with spanning the roof section until the geopolymer is fully cured.
- geopolymer can be easily cut after the initial drying phase. The riser can be made from dry flat sheets that are angle-cut to make the octagon riser.
- the 2 angled floor pieces can be made in the same manner.
- when possible, smaller pieces are easier to work with. Sometimes this is not an option.
- you can make flat molds, once dried, can be cut into the smaller pieces for assembly. The dried pieces can be cut into precise sizes.
- there is considerable shrinkage in the initial drying phase.
Keep me posted on your progress.
Steve Shelton wrote:The metal rod I used was salvaged from a section of cattle panel fence. They were about 1/4" thick or possibly less. The final thickness of the roof pieces should be 2" or more. Imbed the rods in the middle of that 2" thickness.
I suggest you test whatever mixture you come up with prior to your final pour. I went through many component variations before settling on the formula that I used. What you are thinking about trying might be better or it might be worse. The testing process was very time consuming.