Rammed earth is among the oldest building technologies: damp earth compacted in layers inside a temporary form, which is struck to leave a solid, load-bearing wall. It asks almost nothing of its material — dirt: local, abundant, cheap — and everything of compaction and labor. Methods range worldwide, from blocks of wood strapped to the feet to pneumatic rammers with density monitors; Julian Keable’s Rammed Earth Structures: A Code of Practice (1996) surveys its use from aid-organization housing to hotels and villas.
For installations in institutional and artistic settings I use a version adapted to the indoor city — built not from site soil but from the dirt most easily carried inside.
Rammed earth — gallery mix
The mix
In a commercial cement mixer, combine
1 part Miracle-Gro potting mix (the transportable “urban dirt”)
10–20% Portland cement
cement colorant, as needed
The peat and fertilizers give off a strong, ammoniac odor — ventilate.
To build
Lay plastic sheeting under the work — liquid oozes out under the pressure of ramming.
Set the form, then place and ram the mix in layers, exactly as in structural rammed earth (the traditional sequence: site selection, earth selection, testing, form, ramming, de-molding).
After 24–48 hours, strike the form.