[FILLED] Salt and Heritage: prediction and remediation of salt-induced damage to cultural heritage
Fully-funded PhD studentship
Our shared cultural heritage comes in many forms and environments, not all of which are conducive to their long-term preservation. For example, salts are inevitably present in porous building materials like masonry, or natural limestone or sandstone walls. The way salts can migrate through these materials poses dangers to cultural heritage such as wall paintings. For example, salts can be drawn along with water and precipitate out in a bloom of salt on the surface (termed ‘efflorescence’), at interfaces (e.g. ‘blistering’ cement), or within a wall (‘subflorescence’). They can also host damaging bacteria that thrive in high levels of salt. Further complexity arises from the sensitivity of many salts naturally present in building materials to minute variations in environmental conditions. For example, sodium sulphate has two hydration states that both occur near room temperature, but which differ in volume by over 300%: the stresses induced by changes between these states suffices to shatter rocks!
In this project, you will develop models of the physical and chemical processes giving rise to salt-induce damage to wall paintings and other cultural heritage. The aim of the work will be to predict when and where salts will appear for several buildings and sites operated by English Heritage, to inform their conservation efforts.
The project will combine numerical modelling with mock-up experiments and detailed observational campaigns at field sites, such as Farleigh Hungerford Castle, Conisborough Castle, Tynemouth Priory and Cleeve Abbey. The modelling approach is inspired by the methods developed to solve similar problems in hydrology, involving mineral transport through soils. Finite element and pore-network models can capture how fluids move and transport material through porous structures, like sandstone. Within this type of model, salts can move with the water, or diffuse on their own, can precipitate out as a solid and generate mechanical stresses.
In designing and adapting such models you will be guided by extensive data on environmental and physical conditions supplied by English Heritage. You will also travel to these sites to map the transport properties, salts distributions, and how they change over the course of your PhD. With your models further tested by lab-based experiments on the expression of salts in similar materials, your aim will be to make confident predictions about the dangers posed to these internationally important sites by salt-based deterioration and help with the design and monitoring of mitigation strategies.
Fully-funded studentship for UK / International candidates, starting: 2022 / 2023. Jointly supervised by Lucas Goehring (NTU), Ran Holtzman (CU), with Haida Liang (NTU) and David Thickett (English Heritage).
Apply here (closing in 18 February 2022).