Mitigating driving rain to historic buildings: the use of additives in lime-based pointing mortar
Lucie Fusade is a doctoral student at the School of Geography and the Environment. Her current research looks at mitigating driving-rain ingress to historic buildings by using additives in different types of lime pointing mortars.
Holding a Bachelor degree in Art History and Museum studies from the Ecole du Louvre, Paris, Lucie then completed a Master of Art in Heritage Management at Newcastle University and a Master's degree in Architectural History at La Sorbonne, Paris. More recently she completed a MRes in Science and Engineering for Arts, Heritage, and Archaeology (SEAHA) at the University College London (UCL).
Lucie has also worked as an intern for ICOM in Paris and ICCROM in Rome. Her previous research interests focused on built heritage recovery management after Hurricane Katrina in New Orleans and on the impact of restorations on the significance and values of churches bombed during WWII in England.
In England, many historic buildings of architectural, national or local significance, are particularly exposed to harmful environment, especially wind and driving-rain. Rain water and moisture are one of the key factors in the deterioration of building materials, leading for instance to biological growth and dampness. To ensure preservation of historic masonry, rain penetration needs to be mitigated. This is one of the main roles of masonry joints and especially of the surface mortar, called pointing mortar.
A mortar can be made with many combinations of binder, aggregates, water and additives. In most of England's historic buildings the binder traditionally used is lime, sand usually used as the aggregate. The main requirements for a lime-based mortar to be used in pointing intervention on buildings exposed to dampness are that the mortar should be softer than the surrounding masonry, porous, highly permeable, quick at drying and especially able to cure under damp conditions. Considering these criteria, it is necessary to enhance the properties of the lime mortars commonly used. Thus, additives, such as wood ash or crushed stones, can be added to the composition of mortar to enhance different mechanical or physical properties.
This research aims to characterise the physical and chemical roles played by additives in various concentrations with different types of lime. Based on the results obtained in laboratory, some mixes will be applied on test walls outside in order to evaluate their performance when exposed to driving-rain. Later on, selected mixes will be applied on damp historic buildings in collaboration with expert practitioners. By combining laboratory experiments and on-site trials the research aims to develop a repair mortar for specific conservation issues while gaining a scientific understanding of the behaviour of the materials and contributing to sustainable building preservation.
This project is undertaken through the EPSRC Centre for Doctoral Training in Science and Engineering for Arts, Heritage, and Archaeology (SEAHA CDT) in collaboration with Historic England and the Churches Conservation Trust (CCT).