Humidity buffering using stabilised rammed earth materials

The humidity buffering potential of stabilised rammed earth materials is investigated based on the moisture buffer value concept. The moisture buffer value is (a) measured experimentally, (b) calculated from an analytical solution of the mass transfer and (c) simulated using a numerical solution of the combined heat and mass transfer. The numerical solution to the equations is described, as well as the modelling tool termed ‘CHAMP’ (coupled heat and mass transport in porous media). The results show that stabilised rammed earth can be a ‘good’ moisture buffering material under the Nordtest classification scheme. They also show that the moisture buffer value of stabilised rammed earth materials could be optimised or maximised by controlling the grading and mineralogy of the sub-soil and the manufacturing techniques. Sensitivity analysis of the moisture buffer value to the moisture transfer resistance at the surface is explored through numerical simulation and the need to control the experimental measurement carefully is explored.