The Influence of Application Rate of Hydrophobic Treatments on the Drying Behaviour of Brick

Abstract

ydrophobic (or water repellent) treatments have been proposed as a means to mitigate rain ingress and therefore moisture risks associated with internal wall insulation (IWI) on solid (and hence, usually historic) masonry walls. Some practitioners and researchers point out that such interventions may cause unintended consequences, in particular damage to the external masonry surfaces from freeze-thaw or cryptofloresence. Drying behaviour is important in both of these damage mechanisms. It is well established that hydrophobic treatments inhibit stage 1 drying. The depth of penetration also has a direct influence on the stage 2 drying, which is the focus of this work. Three types of treatment (silane-siloxane emulsion, silane only and siloxane only), with three different rates of application (resulting in varying depth of penetration and density of treatment) on a single type of brick, which were subjected to a drying experiment. This influence on stage 2 drying behaviour is explored.