I'm venturing in the construction of my first RMH, but I have a big obstacle, in the area where I live in Canada, there isn't much clay. Not in my property, impossible to find with the landscaping suppliers and very costly to ship or pick up from far. In the other hand we have a incredible supply of rocks, this is the Canadian shield, a vast area of the world composed of mainly rock, and a thin layer of sandy top soil, mostly acidic due to the boreal forest vegetation (conifers/evergreens).
What type of mortar can I use to build the thermal bench for heat exchange, I'm talking about the perimeter masonry work to join the stones, and to fill the space in between the fill of rocks around the tube?
The burning chamber and heat riser I'm building with fire brick and stove cement, and will insulate the riser with fire felt, but my concern really is the "mortar" for the rock work.
Thanks in advance for your comments and ideas. Have a great day!