Primitive Technology

Geopolymer Cement (Ash and Clay) (2024x5)

Ausstrahlung: Mai 02, 2024

I have made wood ash cement before under the assumption that it was the calcium in the ash that gave it its cementitious properties. It may however be a type of geopolymer cement, where the cement is activated by and acid or a base (in this case a base). The acronym NASH is used to remember the material needed: sodium, alumina, silica and H2O. All of these are present in the materials used here. I did some experiments to see how to produce the cement using ash and fired clay from broken bricks. The first method was to take ash from a cold fire and form it into pellets. One pellet was left aside to dry while the others were calcined by firing them in a forge with wood. The calcined pellets were then mixed with terracotta in different proportions (ash: clay 1:0, 1:1, 1:2, 1:3). All samples survived a water test after setting for a week except for the sample made from cold ash that had not been calcined. This demonstrates the need to calcine the ash at a high temperature before use. Next