The craftsman behind the video series Primitive Technology quite industriously fashioned bricks out of a mortar made up of wood ash (leftover from a previous project). Once these were fired and cured, he built a small hut with a Spanish barrel tile roof. This amazing project took more than half a year to complete.
I built a hut from fired clay bricks and mortared them together with a cement made from wood ash left over from the firing process. …The ash left over from firing the bricks was enough to mortar those same bricks together. The hut was 2×2 m and 2 m high at the gables. Wooden beams were placed onto the gables to form the roof and secured in place with mortar. Then I made barrel roof tiles and lay them onto these beams. The whole project took 6 and a half months to build.
Here’s the previous video where he originally formed and fired bricks.