Water-Resistance of Mortars with Lightweight Aggregates

The incorporation of lightweight aggregates in cement-based coating mortars contributes to a better performance of some of their physical properties, influencing their hygrothermal behaviour. This paper analyses the effect of some lightweight aggregates (expanded clay, granulated cork and silica aerogel) on the following mortars’ characteristics: porosity, bulk density, capillary water absorption coefficient, drying index and water vapour permeability. The experimental results showed that low percentages of incorporation of lightweight aggregates led to more porous mortars with lower bulk density, higher capillary water absorption coefficient and greater drying facility, relative to the reference cement-based mortar. The incorporation of silica aerogel in cement-based mortars resulted in major differences in terms of water resistance, with significant benefits in terms of the drying process due to their porous structure.