Air lime mortar consolidation by nanolimes and ammonium phosphate: Compatibility, effectiveness and durability

In this study, a systematic comparison is presented between a commercial dispersion of Ca(OH)2 nanoparticles (so-called nanolimes) and aqueous solutions of diammonium hydrogen phosphate (DAP) for consolidation of air lime mortars. The effects were evaluated in terms of compatibility (composition and morphology of the new phases, changes in color, porosity and water absorption), effectiveness (product uptake, dynamic elastic modulus, scotch tape test) and durability (permanence of the consolidating action after accelerated ageing). While both consolidants proved to be compatible, DAP solutions outperformed nanolimes in terms of effectiveness and durability, especially when highly concentrated DAP solutions were used.