Consolidation of lime mortars with Ca(OH)2 nanoparticles and traditional coatings

Abstract

Lime, Ca(OH)2, has been used for centuries in the composition of both mortars and coatings. Consequently, it is found in many historial buildings and heritage constructions. For this reason, it is necessary to study the most appropriate conservation techniques to be applied in lime mortars restoration. This research addresses a comparison between new and traditional consolidants using physical tests. Firstly, lime mortar specimens were prepared using 1:6 v/v (lime/sand) doses and cured under laboratory conditions for 28 days. The mortars were analysed by optical microscopy, capillary water absorption and permeability tests using Karsten tubes. The shape and size of the nanoparticles of Ca(OH)2 and the ethyl silicate coatings were observed with TEM. Next diluted alcoholic suspensions (5 g/L) of pure Ca(OH)2 NPs were applied on the surfaces. Furthermore, ethyl silicate and sodium silicate were sprayed to compare the different treatments. Finally, the same tests were repeated on the treated materials to compare the effectiveness of the consolidants. The results provided useful information on the consolidation performance of Ca(OH)2 NPs, ethyl silicate and sodium silicate in lime-based mortars. © 2020, University of Cantabria - Building Technology R&D Group. All rights reserved.