Assessing the anisotropy of rammed earth

Rammed earth construction is an ancient technique that is attracting renewed interest throughout the world today. Since it is carried out by stacking layers of rammed earth, it is possible that the rammed earth material is anisotropic. This paper presents the first study of this anisotropy, carried out on two scales. The first is the scale of Representative Volume Elements (RVEs) of the rammed earth material, with dimensions close to those of the walls on site, manufactured and tested in the laboratory. The second is the microscopic scale, for which tests were carried out on equivalent Compressed Earth Blocks (CEBs). A conventional homogenization procedure was carried out to determine the relationships of the microscopic scale and the RVE scale. The compressive strengths, elasticity moduli and failure moduli are similar in both directions of the material: perpendicular and parallel to the layers. The sum of these results allows us to propose the hypothesis that the rammed earth material is an isotropic material of the first order, if the layers remain adherent to each other.