I've been experimenting with cheap ways to improve lo-cost wood-fired earthen ovens. How can I make mud denser, harder, and more durable? Without going to bricks and/or spending a lotta dough? Adding sand to mud reduces shrink and increases density. But clay and sand are generally still less dense (hold less heat) than a good, hi-fired dense firebrick. Hmmm... Experimental Goals: 1. to increase the density and toughness of a clay/sand thermal mix appropriate for building wood-fired ovens (and other wood-fired appliances?), 2. to fabricate a higher quality cast dome ("earth-oven") . . .