Hello everyone.
This is my first attempt at a Rocket Heater so keep in mind I'm very new to this.
I would like to build the burn chamber and riser tube of my
RMH using Fire Clay and perlite. Unfortunately, I can't find Fire Clay (Motar Clay) anywhere. I called all the fireplace and stone dealers in my area. I called all the material suppliers and all the places they recommend and no one carries it. There was one place that was willing to special order Fire Clay for me but they said they would only do it when they are ready to place an order with that supplier and after they order it would still take 4-6 weeks for delivery. However, they recommended a product they carry as a substitute. Alsey Hi-Cast 45 Refractory Castable.
I was hoping to get some input from the community on if this product to determine if it would make a good substitute for the traditional Fire Clay/perlite mix. If not, how could I modify it to make it work.
I had the retailer send me the data sheet on it.
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Description:
Dry, hydraulic setting, high duty refractory castable. HI-CAST 45 is a general purpose 2700°F castable effective for most standard operating service conditions.
TYPICAL TEST DATA -- PHYSICAL PROPERTIES ASTM C-24
P.C.E............................................................................... 31-31½
Temperature Equivalent (melting), °F ......................3061-3090
Service Temperature (max. recommended), °F................. 2700
ASTM C-20 after 2500°F
Apparent Porosity, %.......................................................... 25.9
Apparent Specific Gravity g/cc ........................................... 2.71
Bulk Density lb/ft3
............................................................. 125.2
ASTM C-113 Schedule B % linear
Reheat Change at 2550°F ..................................................... 2.2
TYPICAL CHEMICAL ANALYSIS, Wt. % (calcined basis)
Silica (SiO2)........................................................................ 46.25
Aluminum Oxide (Al2O3) ................................................... 44.88
Calcium Oxide (CaO)........................................................... 4.30
Titanium Dioxide (TiO2)....................................................... 1.90
Iron Oxide (Fe2O3)............................................................... 1.65
Potassium Oxide (K20) ........................................................ 0.60
Magnesium Oxide (MgO).................................................... 0.32
Sodium Oxide (Na20) .......................................................... 0.08
Total.................................................................................. 99.98
Application:
Recommended
water content is 9-12%. [2.5-3.5 US Quarts / 55lb bag.] Actual water content may vary depending on job site conditions. Coverage 55lb sack = .44ft3 Stir dry mix thoroughly and add the correct ratio of water. Return unused portion to the bag. To avoid moisture absorption, store HI-CAST 45 in a cool dry place. Under normal atmospheric conditions, set will occur 8 to 10 hours after HI-CAST 45 is mixed. Heat can usually be applied after 24 hours; however, starting temperature must be held below the boiling point of water to avoid the formation of steam which will result in excessive cracking, spalling and lower strength.
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The two main chemicals in the mix are Silica and Alumina. As I understand (in general terms), the Silica and Alumina work together to create the "Fire Rating" and "bonding agent" for the mix. I believe I could this mix in it's raw form to case the burn chamber and riser tube for my
RMH. However, I don't believe this mix will have the insulating properties that are necessary for the burn chamber and riser tube. Is that correct?
If so, what other materials could I add to this mix to get the insulation properties needed? If I add perlite to this mix at a 50/50 ratio, do you think it would cause the mix to be too brittle? Are there any other readily available materials I could add to the mix to increase the "bonding properties"?
As of right now, the Alsey Hi-Cast is the only option to get my
project started this year. They charge $48 for the 55# pound bad.