Hygrothermal Performance of Lime-Based Thermal Insulation Mortars: Water Absorption, Hygroscopic Sorption, and Water Vapour Permeability

Abstract

Lightweight mortars, which are able to capture carbon, offer moisture buffering and increase the thermal resistance of building elements could be useful for both new and renovated buildings. The hygrothermal properties of lime-based renovation and insulation mortars were studied and the possibilities of reducing water absorption was the main focus of the study. Water absorption coefficient, hygroscopic sorption, and water vapour transmission properties were studied according to EN 1015-18, ISO 12571 and ISO 12572. Hydrated lime was used as the main binder and volcanic sand as an aggregate, white cement and silane in two different concentrations acted as additives. Half of the specimens were kept in forced carbonation conditions (CO2 was added regularly). Drying and carbonation processes were monitored by weighing the specimens regularly. Silane had the ability to reduce water absorption and sorption. Forcing carbonation reduced water absorption and sorption and slightly increased water vapour permeability.