Analysis of the hygrothermal functional properties of stabilised rammed earth materials

Suitable experimental methodologies for determining the hygrothermal properties of stabilised rammed earth (SRE) materials have been presented along with comparative experimental data for three different SRE mix designs with parametric analysis of the influence of these variables on material function. Higher bulk porosity corresponds to reduced volumetric heat capacity (C), but increased sorptivity (S) and vapour permeance (W). Since bulk porosity and void size distribution (VSD) are interdependent variables, it follows that for constant particle size distribution (PSD) and compaction energy an increase in porosity results in an increase in the mean pore radius, for a material. This explains why the magnitude of liquid/vapour transfer (S and W) terms are inversely related to the hygroscopic moisture capacity, ξ since the capillary potential, Ψ will increase when the mean pore diameter decreases. The implications are that the hygrothermal properties of SRE materials can be designed and predicted by manipulating particle size distribution and compaction energy.