How important is mortar in the base?

I am getting ready to start building my base for my oven. Already got the concrete poured and dried for 8 days. My question is what is the purpose of the mortar between the brick? Is it really needed? I will have rebar in every cavity and filled with concrete. Please let me know. Im thinking i will still do the mortar but whats the actual need for it. Also the brick is going to be covered with rock vernier when finished.

Brian,

Welcome to the BrickWood forums! You ask an excellent question. Even with concrete fill in all the concrete block cavities, you should still have some kind of join. That gives your build horizontal strength, while the rebar and concrete fill give it vertical stability. It doesn’t have to be concrete, and it doesn’t have to be between the blocks.

Here is a thread where this was discussed in greater detail:

SBC instead of stucco

Good luck and keep us posted as you progress!