The use of hydroxyapatite as a new inorganic consolidant for damaged carbonate stones

Calcium phosphate coatings for marble conservation: Influence of ethanol and isopropanol addition to the precipitation medium on the coating microstructure and performance

“…The higher consolidating efficacy in samples with higher initial damage is consistent with previous results obtained on limestone [21]. The fact that the "1 M DAP" treatment was able to increase mechanical properties the most, in spite of the presence of cracks and pores in the formed CaP layer, derives from the following fact.…”

“…The idea is forming hydroxyapatite (HAP, Ca10(PO4)6(OH)2, the most stable CaP at pH > 4 [19]) by reacting marble with an aqueous solution of diammonium hydrogen phosphate (DAP, (NH4)2HPO4) [20,21], according to the reaction: 10CaCO3 + 5(NH4)2HPO4 → Ca10(PO4,CO3)6(OH,CO3)2 + 5(NH4)2CO3 + 3CO2 + 2H2O.…”

Consolidation of renders and plasters

“…The natural conversion of calcium carbonate to calcium oxalate led to experiments in Italy, using a treatment based on ammonium oxalate to protect stone and lime plaster against acid rain [22,23]. Later, ammonium phosphates were proposed for consolidation of calcareous substrates and tested on limestone [24,25,26] and mortars. The most important physicalchemical characteristics of common consolidation products are given in Table 6.1.1.…”

Marble Consolidation: Can Nanomaterials Help?

“…Apart from nanoparticle-based products, the current studies are focused on the synthesis and testing of new alternative solutions for marbles, including for example alkoxides [17], hydroxyapatite [21] and oxalates [22]. However, due to the absence of standards on the evaluation and choice/selection of the methods, products performance and operating conditions in relation to the restoration, repair, maintenance and preventive conservation of stone materials, the final assessment of good practices and suitable products is far from its end.…”