DOUGLAS SCRUB MUD BRICK CHALLENGE
FACT SHEET
Materials
- Soil that has approximately 60% Clay and 40% sand
- Straw
- Water
- Spade
- Wheel Barrow
- Moulds (now available to borrow - enquiries, contact
janfhm@senet.com.au.)
Test your soil
Moisten a handful of soil and form it into a ball, as firmly as possible,
drop it onto a hard surface. If it crumbles on impact then the soil is of
the sandy type if it flattens somewhat before breaking then the soil contains
a fair amount of clay.
Bricks should be made with a mixture of soil and sand, too sandy and they
will not keep their form, too much clay and they will crack. If the soil is
one with a high clay content then straw should be added to it to prevent
cracking as the brick dries out.
A more accurate method is to put a cup of dry soil in a mining dish or a
washing up dish and wash the sample with ample water in the same way as gold
was panned, until the water becomes clear. This means that the clay has been
washed away and the remaining sand can be measured. The sample needs to more
than half clay to be suitable for mud bricks.
If your soil has a high clay content then you will need to mix in some
builders sand.
At Douglas Scrub almost pure clay can be obtained from Tobichi Waterhole
adjacent to the mud hut. Remove any sticks and stones from the clay then mix
8 spades of clay with 3 spades of sand to obtain the correct mix of clay and
sand. Also during the mixing process, add straw cut into small pieces.
Mixing
Once you have worked out the correct mix of clay and sand put your soil
(sand and clay) into a wheelbarrow and mix in some water. Mix with your
hands until the mixture is like heavy porridge but not 'sloppy'. You can
also mix it in a hole in the ground and 'puddle' on it with bare feet!
Add straw cut into small pieces (especially if your soil has a high clay
content).
HINT: if you have younger children, have them mix small amounts of clay and sand in a bucket or icecream container, add all the mixture to the barrow then mix all together.
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