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. When I developed wood ash cement years ago in a previous video, it was in response to the need of a cement made from material other than lime stone, which is absent in my location. Wood ash was suitable because it contains calcium oxide, the active cementitious material for making mortar. I made clay bricks and fired them in a kiln made previously. Then I collected the wood ash and made them into pellets storing them for later use. When it was time to make the mortar, I put the pellets in the kiln and fired them. Here it's important to note that the ash needs to be fired at a high temperature with oxygen, ordinary ash from a camp fire won't work as is because they don't get hot enough. It needs to be pelletized and fired again in a kiln before use. I mixed the fired ash pellets with sand (1:3 ratio by volume) and used it to mortar the bricks together.