Pea gravel & stone mass for Liberator rocket stove

I have a large area of rubble, mostly bricks and concrete, on my property shown in the photo. Will these work like the large fieldstone to intersperse in the pea gravel to hold and release the heat in the mass?
My thought was to build the box with 2x4’s and line the inside with a mesh or sheet metal, and cover the outside with cement board. I would appreciate if anyone with experience with building a pea gravel mass could give me some guidance here. Thanks so much!

The more dense the mass, the more effective it will be at storing heat, ie … solid heavy rock with no air voids would be a solid dense mass.
Lots of particles mounded together will contain, or trap lots of  air and would not be dense at all.

So a bucket  of concrete would be very dense, a bucket full of gravel and sand  would not be dense because there will be air separating the partials.

If you want to use gravel, it would be far more effective  to cement the particles together.

However some folk do use pebbles or gravel, just don't expect it to be as effective as a solid mass.

The brick shown on the pile that has holes in it would not be a good solid dense mass, but chunks of concrete would be? Am I understanding you correctly?
In watching the video on the pea gravel mass I learned that pea gravel alone did not work so I planned to use it to fill voids around the chunks of bricks and concrete. Maybe I should make a slurry of pea gravel & mortar and pack around the chunks of concrete as you suggested and forget the bricks.
I have a lot of concrete/brick chunks as in the past this area was a dump site for a local brick mason. The owner was filling in part of a ravine that runs through the property we now own.
Thank you for sharing your thoughts on this. I really appreciate it!