Extruded earth bricks: mechanical and hygrothermal properties, an anisotropic behaviour

Abstract

The study focuses on the mechanical, thermal and hydric properties of extruded earth bricks. The bricks used for testing were produced following an extrusion process in various French brickworks located in the north, the centre and the west of France. Different types of bricks, all solid blocks without perforation, were studied. The compressive strength, the thermal conductivity and the water vapour permeability tests highlight an anisotropic behaviour of the bricks depending on the extrusion direction during the production process. The results confirm that the extrusion process has a major influence on the orientation of clay layers and has an impact on the mechanical and physical properties (perpendicular or parallel to the direction of extrusion). This feature is an opportunity for the brick manufacturers to improve the characteristics of the bricks for wall construction by adapting the laying direction of the brick to the geometry of their bricks and the direction of their extrusion during the process.