Influence of water on the mechanical characteristics of rammed-earth material

Earthen materials in general and rammed-earth in particular are ancient materials used for construction since time immemorial. Some earthen structures built centuries ago are still performing satisfactorily. However, in a lot of cases, the problem of durability still raises questions, since earthen material is very sensitive to water and since the maintenance is not always well done. This paper presents a study on the influence of water on the mechanical characteristics (compressive strength, Young modulus and Poisson ratio) of rammed-earth material. Experiments on suction were also carried out to study the relationship between suction and mechanical characteristics of rammed-earth. The results show that for low water contents: which are from the dry state (in the atmospheric conditions) to 4wt.%, the mechanical properties are constant. Explanations of this result are presented in relation to the capillary force between particles at the microscopic level of the material.