Impact of relative humidity on the mechanical behavior of compacted earth as a building material

Earthen buildings can provide an answer to face difficulties in modern constructions in both terms of sociology, economics as well as ecology. However, the difficulty to understand and to predict their long term behavior represents an obstacle to their spreading. In some cases for example, unsuitable repairs on old constructions can lead to catastrophic situations.More specifically, during their lifetime, earthen walls have to face important variations of indoor and outdoor relative humidity, which induces variations and gradients in their water content. In this context, this paper aims at addressing an important aspect, not yet fully understood: the impact of these variations on the deformability and the strength of unstabilized earth. To that purpose, unconfined compression tests, with and without unload–reload cycles, were performed on different compacted earth samples conditioned at different relative humidities. Tested samples were prepared from materials coming from different existing constructions and sieved at 10 mm. During the tests, the axial and radial strains were measured using non-contact sensors and an image correlation system. This study shows that earthen materials have a complex mechanical behavior, involving the phenomena of plastic straining and mechanical damage. Moreover, both of these phenomena show a strong dependence on the relative humidity at which the samples were stored, as well as on the activity of the clayey portion of the earth.Publisher Statement: NOTICE: this is the author’s version of a work that was accepted for publication in Construction and Building Materials. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Construction and Building Materials, [110, (2016)] DOI: 10.1016/j.conbuildmat.2016.01.027 © 2016, Elsevier. Licensed under the Creative Commons AttributionNonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/