Looking for feedback on my plan for a clay dome with three different layers.

[kappi]

Hi All, new here and looking for some feedback on my plans for my dome. I`m looking into building a three-part dome:

Layer 1: 80/20 clay sand mix. Planning on using clay from my own garden. +/- 3cm thick
Layer 2: Clay/Perlite mix. 5-10cm thick. Not sure on the ratio yet.
Chicken wire mesh
Layer 3: with a 6 1 1 - Sand, cement, lime

Does this make any sense?

[david s]

If it were mine I be using some different numbers.
1.1 part clay 2 parts sand by volume. The clay should be in dry powdered form and mixed dry for a consistent mix before adding water.. A high proportion of clay results in a lot of shrinkage (cracks) generally, for strength the wall thickness needs to be at least 2”

2. The insulating mix should have as little clay content as possible for maximum insulation value and be around 4” thick. Best again to mix dry ingredients first before adding water. A 10:1 mix is about as lean as you can go whilst still retaining a workable mix. For every 10 parts perlite add 3 parts water. So 10 perlite (or vermiculite) 1 part powdered clay, 3 parts water.

3. 6:1:1 is a bit weak. 4:1:1 is better. Make sure you use hydrated lime.

[kappi]

Thank you, great info. I`ll definitely look into this a bit more! Appreciated!

[Petter]

If you like experimenting, test your clay. Every clay is unique. Make different sand ratios and water additions. When wet, mark a 100 mm distance and measure shrinkage after drying. Should be a few mm at the most.