Nanolime, nanosilica or ammonium phosphate? Laboratory and field study on consolidation of a byzantine marble sarcophagus

The present paper aims at comparing commercial nanolime and nanosilica dispersions with an aqueous solution of diammonium hydrogen phosphate (DAP) for consolidation of marble. The consolidants were first tested in the laboratory on artificially and naturally weathered marble specimens. The DAP-treatment applied by poulticing outperformed nanolime and nanosilica in terms of consolidating effectiveness, while showing good compatibility with the substrate. After preliminary testing of all the three consolidants on small areas of a byzantine marble sarcophagus, the DAP-treatment applied by poulticing was finally selected for application onto the whole sarcophagus. Field results confirmed the promising performance of the DAP-treatment.