Evaporative drying in stabilised compressed earth materials using unsaturated flow theory

The evaporative drying of saturated and unsaturated stabilised earth materials is explained using the 1-dimensional sharp wet front approximation. The mechanisms of both sorption and desorption are described using unsaturated flow theory. The concepts of Stage 1 and Stage 2 evaporative drying rates are discussed in relation to moisture condition values in earth materials with a clear description of the transition between stages. An approach towards obtaining a wide range of void size distributions (VSD) within the matric structure is presented where mass proportioning of granular particles above & below a threshold diameter establishes maximum and minimum values for PSD, which can then be theoretically controlled by varying compaction energy. For the PSD range used in this study, a threshold diameter of 3.35 mm was set and a target ratio of ∼5 was used for parametric analysis of suction-related variables. Experimental testing of stabilised earth materials showed that, for low matric suction materials where 3.35 ratio ≤5, the rate of moisture transport was reduced. They were quicker to absorb water and to dry out (despite slightly lower evaporation rates) resulting in less surface cooling and less matric heat transfer. The converse was true for higher matric suction materials. This technique enables the controlled modification of hygric and thermal properties in stabilised earth materials.