Ok to use Hempcrete as mass for rocket stove mass heater?

I searched but couldn't find a topic that addressed this. I want to put a rocket stove mass heater in a skoolie, but don't want the weight of fully conventional. Can hempcrete be used instead of the mainstream materials?

Thanks in advance.

The mass is the point; using less-dense material will probably reduce the heat-storage capacity and possibly insulate instead. I would just use a thinner layer of cob or masonry around your heat exchange element, and enjoy the reduced footprint.