Published on May 09, 2024

Primitive Technology: Geopolymer Cement (Ash and Clay)

Step-by-Step Guide:


Step-by-Step Tutorial: How to Create Geopolymer Cement from Ash and Clay

Materials Needed:

  • Wood for burning
  • Clay
  • Water
  • Aggregate (old, broken bricks or pottery)
  • Sand (optional for experimentation)

Step 1: Making Ash and Clay Mixture

  1. Start by making fire by friction at the brick making hut using wood.
  2. Burn the wood to produce ash, which will also help in drying bricks.
  3. Sift the ash to remove most of the charcoal.
  4. Mix water with the ash to form a paste.
  5. Form the ash paste into pellets or clinkers to be fired. Set one pellet aside to air dry.

Step 2: Calcining the Ash Pellets

  1. Calcine the remaining pellets in a forge by burning them one by one with wood until they glow red hot.
  2. Once properly calcined, mix the pellets with water again to form the cement mixture.
  3. Form the mixture into desired shapes, such as cubes or blocks.

Step 3: Adding Aggregate and Testing

  1. Crush old, broken bricks or pottery to form a fine aggregate.
  2. Experiment with different ratios of ash to fired clay or sand (1:1, 1:2, 1:3) to find the desired strength.
  3. Allow the samples to cure for a week, then perform a dissolving resistance test by putting them in water for about 30 minutes.

Step 4: Making a Furnace Grate

  1. Create a grate for the furnace using clay and ash clinkers.
  2. Position the grate in the furnace and stack wood on top.
  3. Light the fire from the top to reduce smoke and improve efficiency.

Step 5: Experimenting with Different Mixtures

  1. Crush half of the calcined clinker and mix it with sand instead of fired clay for experimentation.
  2. Test different ratios of ash to sand or clay to observe the strength and durability of the samples.

Step 6: Fast-Setting Geopolymer Cement Experiment

  1. Use the ash left over from the previous firing without further calcining.
  2. Try a 1:3 ratio of ash to fired clay to create a fast-setting geopolymer cement.
  3. Test the sample after 6 hours to see if it survives in water for 24 hours.

Step 7: Scaling Up and Further Experiments

  1. Conduct more experiments to scale up the process and explore different structures that can be made using the geopolymer cement.
  2. Continue testing different ratios and materials to optimize the strength and setting time of the cement.

By following these steps and conducting experiments, you can create geopolymer cement using ash and clay, exploring different mixtures and ratios to achieve desired properties for various construction projects.