Soilogogy - finding the right mix

Having obtained the clay rich soil, it is now necessary to find the right mix to use it for our walls. We need it as both infill, but also consider it as a finish for some walls. A useful mix can be obtained by combining clay, sand, fibre and water, alas the optimum combination is difficult to find as the clay content and type varies. I therefore tried our different combinations on a spare wall.

This Video shows the mixing process:



The mixtures:

1. Sand 0 handfuls, red earth 10 handfuls



This mixture was nice and sticky but developed large cracks after drying.


2. Sand 5 handfuls, red earth 10 handfuls



This mix was also nice sticky, but cracks still occurred even though less than the previous mix.


3. Sand 10 handfuls, red earth 5 handfuls



By having double the amount of sand compared to red earth, cracking could be removed strongly. However, they are still present.


4. Straw 4 hand bushels, Sand 5 handfuls, red earth 10 handfuls



This mix hardly developed any cracks, thanks to the added straw.



Overall I think I used too much water in the mixes, and next time I will try to measure the amount of water going in. I would also like to see what will happen when I use finer sand, or use shredded paper (from the office) to add texture.

When applying the final mix to our walls, we should usually use several layers. The first one can be crude, and cracking may actually help the next layers to bind and stick better. Top and finishing layers should be smooth, so that water cannot erode the wall.