Undergraduate Course

Department of Chemistry University of Oxford

BREATHING STONES: A Part II Research Project for Chemists with the School of Geography and the Environment

Prof Grant Ritchie, Prof Heather Viles

Many important heritage buildings, monuments and sculptures in historic cities are constructed of limestone, for example the Radcliffe Camera in Oxford. Limestone is prone to deteriorate in polluted atmospheric conditions (high concentrations of SO2, NOx) and in the presence of water. In response, many chemical conservation treatments have been developed to try and slow down the deterioration, e.g. photocatalytic nanolime has been developed which creates a sacrificial layer which can react with atmospheric pollutants, reducing the level of pollutants and preventing further damage to the limestone. Understanding moisture relations at the surface of limestone is fundamental both to understanding the reactions involved in limestone deterioration and to judging the success of conservation treatments. This is hindered by the current techniques available to monitor moisture in building materials, which indirectly measure the sub-surface moisture content and require calibration.

This project aims at addressing the lack of  high resolution, near-surface non-destructive quantitative methods to monitor water vapour and pollutant gas exchange in limestone by using near- and mid-infrared laser absorption spectroscopic methods, in particular cavity ring-down techniques. An advantage of these techniques is the ability to distinguish between different species, and even different isotopes, and therefore isotopic analysis will be used to investigate the water transport properties of limestone, for example the drying kinetics under different environmental conditions. This project will also investigation the combination of this technique with other optical methods, such as Gas in Scattering Media Absorption Spectroscopy (GASMAS), to allow the surface water content to be monitored alongside the drying kinetics of limestone. Following this, investigations into the flux of key atmospheric pollutants, e.g. SO¬≠2, into and out of limestone, and the effect of conservation treatments on the limestone will be carried out.

The student will be supervised by Grant Ritchie (PTCL) and Heather Viles (School of Geography and the Environment).

For more information contact:
Grant Ritchie (grant.ritchie@chem.ox.ac.uk)
Heather Viles (heather.viles@ouce.ox.ac.uk)