Linking climate change, moisture dynamics and salt movement within natural building sandstones: implications for salt transport by diffusion

Future climate change scenarios for much of the UK suggest that the key stone decay controlsof temperature and moisture input will change. Seasonality in precipitation is projected toincrease, essentially meaning that winters are due to become wetter, while summers are likelyto become drier. For building stones, this translates into longer ‘time-of-wetness’ periodsduring winter that are linked not simply to surface wetness, but specifically to ‘deep wetting’.Data from sandstone test walls in the wet west of Northern Ireland demonstrate the build up ofinternal moisture related to cumulative rainfall. During initial moisture penetration, salts canbe re-distributed in solution, but once blocks become saturated it is likely that further redistributionwill occur through ion diffusion. This paper seeks to make links between climatechange, stone moisture dynamics, and ion diffusion, experimenting to assess how quicklydiffusion takes place in building sandstones and the potential deleterious chemical effects ofsalts held in solution