"As instructors ... worked ... to develop a forming system that would allow their students to build the classroom facility, the wide applicability of such a system became apparent. Rammed earth wall systems are currently fairly expensive, as the necessary formwork constitutes a major investment and the labor is specialized.... An alternative method of forming walls incrementally, with formwork that could be managed by two or three people and then reused, was necessary for low-cost building."
(and a little further down)
"Formwork design and testing focused on the goals of easy mobility and reassembly. Early prototypes developed by Brittain and Perry used plywood walls stiffened with steel sections (later replaced by aluminum to lighten the forms' weight). Aluminum angles allowed the plywood pieces to bolt together easily and doubled as handles for moving the forms. However, the pressure built up during tamping made disassembling the forms very difficult. The sides bowed in spite of the stiffeners, the assembled forms were hard to move around, and they could not be stacked one upon the other. This forced a working sequence of ramming walls in horizontal courses, with the drawback of a small amount of horizontal form creep in the direction of the wall-building. After consulting with noted rammed earth expert David Easton and reviewing precedents for ramming walls in vertical piers (ancient and contemporary Chinese, Moroccan, and Australian methods), plywood walls, pipe clamps, and stiffening boards were used in a simpler configuration. After a few test runs with the revised formwork, fine-tuning of pipe spacing and placement allowed actual construction to begin."
Mary Hardin, Rammed Earth Constructions: Trans-cultural research in the Sonoran Desert.
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Crazy the things you find on the internet. That little gem was gotten here. But be forwarned--the material is from the University of Arizona College of Agriculture and Life Sciences, and as such, deals with so-called "agricultural formwork." If so-called "agricultural formwork" is somehow beneath you, then perhaps this isn't the site for you.
Otherwise, enjoy this informative, inspiring and well written paper.