In the north western corner of Serbia lies Bac Fortress.
It’s a XIV century castle – now considered a national heritage monument – which was destroyed 300 years ago and has been lying in ruins ever since.
Yet, despite huge conservation efforts, it is still under attack today.
Slavica Vujovic is a Conservation Architect from the Vojvodina Institute for the Protection of Cultural Monuments: “We are actively trying to consolidate it, but the structure remains very fragile. Clay bricks used in the walls have deteriorated badly. And we have discovered there aren’t even any foundations under the walls in some places; which further risks its stability”.
But now European researchers have joined archaeologists and conservation workers to look for solutions to these problems.
They are working to see what’s inside and underneath these walls.
And this research has enabled them to develop an innovative material, a new coating, specially conceived to protect these old bricks in an environmentally friendly way.
Ognjen Rudic is a Materials Engineer at the University of Novi Sad in Serbia: “We are currently testing this new coating material. It is completely natural. There aren’t any toxic elements. I could safely drink it if I wanted to”.
This research aims to help to develop new ‘green’ products to protect cultural heritage sites damaged by frost, organic agents, chemical corrosion and other ‘weathering’ processes.
Called ‘Heromat’ the project coordinator is Jonjaua Ranogajec. She is a Materials Engineer at the University of Novi Sad: “We’ve developed two innovative materials; one to consolidate the structure; another to preserve it. We think they are truly green and environmentally friendly; made from silicates and carbonates, they have a very similar composition to the bricks, mortar and concrete used in these walls”.
Field research enables scientists to have a precise idea of how bricks and mortar were made in the Middle Ages.
Then, in the lab, they take the same clay and other raw materials and, by using the same production methods, almost perfect replicas are manufactured.
And then the research gets really, well, tough.
Snezana Vucetic is also a Materials Engineer at the University of Novi Sad: “Once fabricated, we have to artificially weather these replica bricks. So we expose them to salt and freeze-thaw cycles. We also expose them to sulphur dioxide and carbon dioxide and we attack them with polluting microbiological agents”
After this, the conservation and preservation materials, which are also made in the lab, are sprayed on the now weathered replica bricks to see how well the coating works.
Results from these trials are carefully assessed and scientists say preliminary findings have been quite encouraging.
Ognjen Rudic again: “Our research shows this preservation material does have photocathalytic properties. It is also self-cleaning and anti-microbial: it destroys any organic materials that could alter the surface of the bricks. And it is transparent; it does not change the aesthetic appearance of the building material you want to preserve”.
HGP, a building materials company which usually makes stucco and plaster, has joined the project.
It is now it hosting a pilot production site and testing facilities for these new conservation materials. And there is a very good reason for this. Profit.
The Technical Director is Rajko Travica: “It is a very innovative product that could improve our market placement. It is made of simple materials, it’s easy to mix and produce. If the research proves it’s effective, this product could be in the market in around 3 years”.
And that would be good news, researchers say, not just for the conservation of old bricks in Serbia, but at thousands of other cultural heritage monuments around Europe.