Natural stone is one of the most widely used geological construction materials. Although stone masonry structures have the potential to survive over centuries, they may be subject to significant damage and deterioration. Various conservation treatments have been explored for modifying the characteristics of stone, often in the layer closer to the surface. However, treatments may limit the breathability of the material triggering further damage.
Microbially induced carbonate precipitation by bacteria is a promising breathable alternative for the protection of building stone from deterioration. The mineralogical composition and pore structure of most stone types used in construction are favourable for the growth of bacterial communities. However, the protection layer will deteriorate in the same manner as the host material, and although it will give enhanced protection of the stone, it is not infinitely durable. By giving this microbiological protection system the ability to ‘self-heal’ (i.e. respond automatically to heal damage and deterioration, without human intervention), it has the potential to considerably extend the durability of masonry protection.
During the GEOHEAL project, our objectives focused on the development, application and assessment of biological healing and self-healing mechanisms for repairing and preventing damage in cementless construction materials, such as natural stone. The direct compatibility of the biological healing products, such as calcite, with stone materials, enables their application in heritage conservation, and significant reduction of maintenance costs in both existing and new structures. There is the potential for other minerals to act in a similar way, and which may be more durable (e.g. oxalates).
