Poured Earth as concrete

Abstract

International audienceIn order to pour an earthen material in a liquid state, as a concrete, technologies used by concrete and ceramic industries can be transferred to the field of earthen construction. Two different methods should be employed simultaneously. The first relates to theories of grain packing that have led to models of Apollonian packing and spaced packing, commonly used for the development of cement concrete (ultra high performance concrete and self-leveling concrete). It concerns the optimization of the granular skeleton of natural materials. The second relates to the dispersion of the colloidal fraction of earthen materials. In natural soils, clays are organized as porous aggregates composed of several tens of particles. These aggregates trap water that is not used to liquefy the mixture. The dispersion of these aggregates, releasing this interstitial water, liquefies the earthen material without adding water. This dispersion is obtained by adding a small proportion (on the order of a few tenths of a percent by mass relative to the dry material) of deflocculating agents such as those commonly used for the development of industrial ceramics. The combined action of these two methods leads to a solid material that does not crack while drying, and can easily be implemented at a viscosity comparable to that of vibrated concrete with the same tools than those employed by the concrete industry (cement mixer, shuttering, vibrating needle). This new technique is particularly suited for the implementation of slabs and other horizontal surfaces, and also for vertical walls