Compression behaviour of non-industrial materials in civil engineering by three scale experiments: The case of rammed earth

In order to give an example of a scientific approach adapted to non-industrial materials, we chose to study a structural element: a load-bearing building wall made of rammed earth material. Rammed earth construction is an ancient technique which is attracting renewed interest throughout the world today. Although rammed earth is currently regarded as a promising material in the construction sector in the context of sustainable development, it is still difficult to quantify its durability, as well as its thermal and mechanical performances, which discourages people from using it. This paper is devoted to the study of the last problem. Three different scales were studied. The first is the scale of in-situ walls. Dynamic measurements were carried out on site to determine the Eigen frequencies of the walls. The elastic modulus was determined from the frequencies measured by using a finite element model. The second is the scale of a representative volume element (RVE). Rammed earth RVE samples with dimensions similar to those of the walls on site were manufactured and tested in the laboratory. Finally, at the last scale, called the micro-mechanical scale, tests were performed on equivalent compressed earth blocks (CEBs), which can replace the rammed earth RVE samples to facilitate laboratory tests.