Building arches with
rammed earth needs some forward planning. The shape and size of the
arch needs deciding, and then the block-out or displacement box has to
be made. Once made, the same shape can be repeated indefinitely,
giving a different feel and rhythm to what is being built.
There are plenty more
images of
rammed earth arches.
As with all rammed earth
the box is the wall, more detail in the box means more detail in the
wall. The more inserts in the wall the less earth, and the less
ramming, but also less strength, so this needs to be thought through
carefully.
In the job shown formwork
was made from 18mm plywood and 75mm x 50mm timber. The two arch
blockouts were made from ply facings, cut to the shape of the curve,
50mm x 25mm battens separate the two ply faces and a triple hardboard
skin is flexed over to give the inside of the arch its smooth finish.
Also a square facing board
was fixed on the outside face of the wall with a chamfered edge as a
purely decorative feature, extremely easy to achieve.
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