Towards an easy decision tool to assess soil suitability for earth building.

• There is no common agreement on how to assess soil suitability for earth building. • A large sampling campaign was achieved on rammed earth heritage buildings in France. • The samples were analysed through laboratory tests. • The tests included water content, dry density, sieving, hydrometer tests, MBV, PI. • Current classification systems relying only on granularity appeared inappropriate. • A classification system based on granularity and clay activity is recommended. In the European Union, most of the wastes from the building sector are composed of earths. Earth construction may be an interesting outlet for the re-use of these wastes, while meeting the challenge of circular economy: in particular, it involves low-embodied energy processes and earth material can be re-used for building by end-of-life. Nonetheless, the identification of suitable earths for construction remains an issue. To overcome this problem, an option may be to analyse earth building heritage, which is at least one-century old in Europe: indeed, earth employed in these buildings can be regarded as "time-tested", and thus suitable for construction. In this paper, more than 20 different earths collected in rammed earth heritage building in France are presented. The results are confronted both to literature and to several classifications employed in soil sciences. A classification system based on granularity and clay activity will be relevant to address the convenience of earth for building purposes. [ABSTRACT FROM AUTHOR]