Geomaterials such as pavement materials and soils are commonly stabilised with cementitious or other binders when it is necessary to upgrade the performance characteristics of the original material for a particular engineering application. Typical examples include construction or in situ rehabilitation of road pavements, formation of stabilised bases in soft or reactive soils and deep-mixing of soils. When these layers are placed at or close to the ground surface (or generally above the water table), they mostly operate under unsaturated conditions. When free water becomes available at or close to the edges of these layers, water ingress will take place predominantly by capillary action. A typical field situation idealizing the pathways for capillary water ingress with reference to a pavement layer is shown in Figure 1.