Strength properties of soil wall materials for seismic performance evaluation

A rammed earth technique is a traditional architectural technique to build soil structures by compressing clay, sand, gravel, in a form. The walls built with the rammed earth technique are seen sometimes in historical heritages, and are attracting interest in construction projects of a modern housing due to their advantages in recent years. However, the mechanical properties, especially tensile and shear strengths, of rammed earth materials have not been fully investigated. Therefore, the mechanical properties of two kinds of rammed earth materials are evaluated by conducting a series of unconfined compression test, unconfined tension test and drained triaxial compression test in this study. As for a rammed earth material without quick lime, the unconfined compression strength increases with decrease of the water content; the unconfined tension strength is approximately 10 % of the unconfined compression strength; the drained triaxial compression tests show that peak strength increases with the confining stress, while the stiffness is rather independent of the confining stress.