Author(s)

Q.-B. Bui, S. Hans, J.-C. Morel & V. Mollion

Abstract

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. Keywords: rammed-earth, influence of water, suction, compressive strength, young modulus, poisson ratio. 1 Introduction The rammed earth is a clayey soil (earth) compacted into a formwork. The earth composition varies greatly but contains no organic component and enough clay, which acts as a binder between the grains, a mixture of silt, sand, gravel and stones with a diameter of a few centimeters. Compaction is performed using a water content considered optimum, i.e. that provides the highest dry density for a fixed compaction energy. The rammed earth is composed of several layers of

Keywords

rammed-earth, influence of water, suction, compressive strength, young modulus, poisson ratio