I made a mix to start building up the heigh of the foundation and provide a containment ring for the oven.
clay source: a brick company's clay soil. I was told it was close to 80% clay
I did a 2 parts sand to 1 part clay mix
didn't measure the amount of straw.
the result was really hard but also sort of easy to pull off of the stones.
not enough sand?
not enough straw?