While developing and building fabric formed rammed earth (FRE) technology, I have discovered interesting aspects of FRE. One of the interesting features is that materials and builders can play an active role in design. The general outline of FRE can be controlled and estimated, but the detailed design of FRE is completely dependent on materials and builders. This is associated with the nature of fabric. Because of the flexible quality of fabric, the fabric’s form can be dramatically changed. Fabric looks loose before compaction starts, but it bulges gradually during the construction once fabric formwork is filled with soil. The extent of fabric’s bulging can vary according to the compaction from builders. The higher compaction is given, the more bulged form is produced. This significantly differs from rigid formed rammed earth: rammed earth’ form is restrained by rigid timber or steel formwork, so materials and builders’ roles in design are very much limited.
While comparing the photos of rammed earth walls I built, I discovered how the form of FRE can be significantly different according to compaction. The left photo shows the rammed earth wall that I built with a manual rammer in South Korea, while the right photo shows the rammed earth wall that I built with an electric rammer in Edinburgh, UK. They were built with a similar fabric formwork, so the appearances are similar at first glance, but the profiles are a lot different. As you can see in the photos, the rammed earth wall on the right has more distinctive undulation. That is because an electric rammer has a bigger compaction, so it contributed to creating more bulged forms.
Building fabric formed rammed earth with a manual rammer (left) and an electric rammer (right)
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