Micromechanics modelling of cement stabilised rammed earth

Abstract

Rammed earth (RE) is a generic term for a number of construction materials that contain stabilised or non-stabilised earthen materials. RE materials are heterogeneous and their bulk performance depends on their mineralogical composition, physical texture, water content and mode of preparation. This category of building materials has recently been the subject of extensive studies, given the increasing interest in sustainable construction. This trend has highlighted not only the potential of RE, but also the lack of standards and guidelines that can promote its adoption by architects and builders. Predictive modelling techniques that faithfully forecast the mechanical behaviour of RE are also scarce. This study introduces a micromechanics approach and proposes a multi-scaling model to predict the mechanical behaviour of cement stabilised rammed earth (CSRE) in linear elasticity. The RE heterogeneity is addressed hierarchically at different scales separated by the sizes of their representative volume elements (RVE). Homogenisation procedures are applied to predict the material properties at each scale and investigate the overall macroscopic behaviour of earthen mixtures. The Mori-Tanaka homogenisation scheme is used to predict the linear elastic behaviour of CSRE by treating it as a porous composite. The theoretical results obtained by the application of various micro-mechanics-based models (Reuss-Voigt, Hashin-Strickman, Mori-Tanaka and Self-consistency) are assessed by comparison with the experimental data. The Mori-Tanaka homogenisation scheme proved to predict the material's macroscopic linear elastic behaviour fairly accurately while taking into account local heterogeneities.