SALTS ACCUMULATION EFFECT ON DURABILITY OF NON-HYDROPHOBISED RENOVATION PLASTERS.

This paper focuses on the experimental testing of hydrated lime-, natural hydraulic lime-, and lime-cement-based mortars with improved salt accumulation capacity. Moreover, the effect of varying content of non-hydrophobised expanded perlite (EP) in the mortars on their durability was investigated. The substation of silica sand by expanded perlite was 25%, 50%, 75% and 100% by volume. A modified method based on the adsorption of free salt ions from solution was used to measure the chloride binding isotherms. The salt concentration was analyzed using an apparatus working on liquid chromatography technique. The data acquired were compared with reference mortars with natural silica sand as an only aggregate. The use of expanded perlite significantly increased the chloride binding capacity of the tested mortars, while no deterioration was observed for samples contaminated with salts. The results obtained thus validated the applicability of most of the mortars tested for the repair of masonry structures including the restoration of renders and plasters. When repairing historic masonry, compatibility issues must be considered, in this case with respect to the type of binder used. [ABSTRACT FROM AUTHOR]