Mechanical characterization of natural fibre-reinforced earth plasters
The Bioterra ANR project aims to identify, characterize and offer solutions with low environmental impact, to microbial proliferation on earth bio-based products (bricks and plasters). As part of this project, this paper deals with the mechanical characterization of earth plasters: the objective is to identify products meeting the main conditions of use for construction, as a basis for further research on microbial development. Several testing methods are presented and are applied on 2 different plaster formulations composed of clay, sand, water and various natural fibers. The following properties are studied : shrinkage, compressive strength, flexural and Brazilian tensile strength, abrasion. The testing procedure includes the preparation of large plaster slabs to ensure a representative fiber distribution within the test specimens. The plates are dried under stable humidity conditions and the drying process is monitored by successive weightings. Then the specimens are cut inside the plate for mechanical testing. The paper shows a full description of the testing procedure and presents the resistances obtained for various plaster formulations. It yields interesting results about the expected properties of natural fiber-reinforced earth plasters and proposes some criteria for product acceptability.