Unsaturated Soils: Advances in Geo-Engineering – Toll et al. (eds) © 2008 Taylor & Francis Group, London, ISBN 978-0-415-47692-8 Unsaturated characteristics of rammed earth

ABSTRACT: Rammed earth is both an ancient construction technique and the name for the material produced by the technique. Rammed earth is gaining in popularity around the world due to its ecological and sustainable attributes. Walls of rammed earth are formed by taking a graded mixture of (usually) locally-won soil and compacting the mixture between formwork in a similar manner to concrete. The formwork is then removed leaving a solid earth wall. There is little scientific understanding of the source of strength in rammed earth and design to date has used empirical approaches. In this paper we consider rammed earth as an unsaturated soil thus explaining one source of strength to be from suction. Laboratory tests have been carried out on rammed earth samples including unconfined compression and Brazilian tests (to measure strength) and filter paper tests (to determine the water retention properties). The tests all indicate that a source of strength in rammed earth derives from suction and conclusions are drawn as to their levels in ancient rammed earth structures.