Use of diluted Ca(OH)2 suspensions and their transformation into nanostructured CaCO3 coatings: A case study in strengthening heritage materials (stucco, adobe and stone)

Abstract In the conservation of heritage materials, the effectiveness of diluted nanolime suspensions in consolidating surfaces is scarcely explored. This paper aims to examine the surface modification of stucco, adobe and stone by deposition of Ca(OH) 2 nanoparticles. The nanoparticles were applied in five consecutive coats and transformed into CaCO 3 by atmospheric CO 2 creating a compatible coating with the surface. The coatings were studied by erosion tests (pull-off tests) and examined by scanning electron microscopy (SEM) and optical microscopy. The tests confirmed the surface resistance was clearly improved due to formation of nanostructured cementing CaCO 3 coatings. In addition, the coatings did not practically alter the surface colour due to the diluted nature of the suspensions. To conclude, Ca(OH) 2 nanoparticles-based coatings are appropriate solutions to extend the durability of traditional heritage materials, such as stucco, adobe or stone.