Consolidation of weathered limestone using nanolime

Abstract

Limestone sourced from Salisbury Cathedral and Bath Abbey (UK) was treated with commercially available nanolime of concentration 25 g/l. The response of the stones to the treatment was studied using a variety of analysis techniques including optical microscopy, electron microscopy, drilling resistance measurement and mercury intrusion porosimetry. Weathered and non-weathered surfaces of both types of stones were compared. All the specimens were characterised before and after the treatment to determine any changes in their properties caused by their weathering and by the treatment itself. Results show that the degradation processes of the stones strongly affect their interaction with nanolime consolidation treatments. Drilling resistance measurements of treated and untreated samples were compared. After 20 days significant increases in sub-surface drilling resistance was observed in the non-weathered Bath stone and a small increase in the weathered Bath stone after 6 months was also noted. Both weathered and non- weathered Chilmark stone showed an increase in drilling resistance after 6 months, however at 20 days this was most evident in the samples treated with nanolime in isopropanol as opposed to ethanol.