i3Dc – Session S13

Optimizing earthern construction using rheology

Prof. Arnaud Perrot
Université de Bretagne Sud

Abstract: Earth-based materials are currently receiving much attention as sustainable and local construction materials with sufficient mechanical strength for affordable solutions worldwide. However, contrarily to concrete and cement-based materials, only a few studies deal with the rheological behaviour of such materials and its link with processing route. It is worth noting that there is a broad range of processing routes for earth-based materials which impose different rheological or consistency requirements for the earth materials. Depending on its nature and the water content, earth materials can be granular-like, pasty or fluid-like materials making the material more adapted to specific processing routes than others. It is here shown that in vernacular construction techniques, the earth nature and achievable consistencies have imposed the processing routes and influenced the material hardened or service life properties. Inspired by these observations, it is now required to adapt the material “fresh” properties to the processing methods (or the contrary) in order to obtain the best of the materials in terms of mechanical and service life properties. To reach this goal, concepts taken from concrete mix design and processing as well as geotechnical and rheological characterization tools can be used and beneficially applied to earth construction. For example, using admixtures can be a solution in order to design and cast earth-like concrete or to meet rheological requirements for 3D printing methods. The presentation aims to provide an overview of earth construction methods with materials specifications and rheological requirements. Finally, the effects of different admixtures on earth processing are also presented with an emphasis put on bio-based solutions.

Short Bio: Arnaud Perrot is associate researcher at université de Bretagne Sud since 2007. His research topic mainly deals with construction materials rheology and processing. He has written more than 60 papers in international journals dealing with this topic. He is an active member in RILEMtechnical committees to concrete 3D printing and rheology and deputy chair of the newly launched committee on the processing of earth-based materials. He is associate editor of RILEM/Springer Materials and Structures journal.