HSE University Alumna Develops Technology to Repair Karst Sinkholes

This year, the first cohort of the international master’s programme ‘Prototyping Future Cities’ earned their degrees. Among those graduating with honors was architect Anna Budnikova, who invented a unique technology to reinforce karst sinkholes with fungal spores.

Biotechnology to Save Kazan

Two years ago, Anna Budnikova and three other graduates of universities in Kazan received a grant from the President of the Republic of Tatarstan and enrolled in HSE’s English-taught master’s programme ‘Prototyping Future Cities’. Initially, Anna was interested in hydrology: before applying to the master’s programme, she had been working on a project related to the monitoring of urban water usage, and she planned to continue research in this area.

One of the grant requirements was to design a project that would benefit Kazan.

‘Since we had such an opportunity, we wanted to do something for Kazan. The city stands on a karst platform. Groundwater destroys the rock, which regularly causes sinkholes. This complex hydrogeology topic is surprisingly applicable both to architecture and the materials used in architecture,’ says Anna.

As a result, the focus of research shifted to studying karst sinkholes and looking for new ways to repair them.

Elena Mitrofanova, a Leading Expert at Shukhov Lab, supported the idea, and in February 2019, Anna began work on the project  under her supervision. ‘We switched to a specific location in Kazan and found a problem area with deteriorating karst layers,’ says Elena. ‘These days, when karst sinkholes form in the city, they are filled with various materials. We thought that we could treat these sinkholes as a new architectural morphology with the use of biotechnology and self-healing systems, which researchers have been actively developing over the last several years.’

Creating MYCOKARST. The Research

Before starting her work on the technology that would later be called MYCOKARST, Anna studied the existing research in this area. Researchers at Binghamton University (USA) had used fungal spores to restore calcite walls and bricks, and today they are studying the spores’ ‘self-healing’ potential in concrete. A team of scientists from Delft University (the Netherlands) began similar studies of self-healing materials in 2014-2015 and created a working prototype, but it has not been put into production yet. Using this technology, the researchers use expensive bacteria, a single  small bag of which costs about 60,000 rubles in Russia.

‘I located the problem in karst. Interestingly enough, no one had worked with it before, although it is something pretty obvious that affects places all over the world,’ says Anna.

Karst sinkholes in cities are unpredictable. Filling them with concrete is a bad solution, but there is currently no other effective way to repair them

Anna decided to study the problem and try to reinforce the sinkholes following the Binghamton University researchers’ methodology, using fungal spores of Trichoderma reesei mushrooms, which can be found in Russia, instead.

The Experiment

Anna looked at all types of sinkholes, from small ones to big samples with a diameter of up to 300 meters. The main risk in reinforcing such sinkholes is that the biomaterial may not settle in all areas, and they therefore require a lot of repeated tests. In the initial stages of her work,  Anna consulted with an expert from Kazan Federal University. He advised Anna to look at karst places near the Noksa River, where they found a karst ravine about 5 meters high and 7 meters wide.  The researchers then selected an area of the ravine for testing.

‘Let’s suppose that there is a problem area or an existing sinkhole. The technology is simple: we spray fungal spores onto the soil surface, about 20 g per square meter,’ explains Anna. ‘Before that, we need to check the soil composition: to start the process, we need calcium, which is usually present in karst soils. If there is not enough of it, we add an additional layer of ash or dolomite powder before spraying the spores. I think that in future, this might be performed by a drone or another form of robotic technology.’

After that, everything works in natural climate conditions. For fungal spores to develop, a temperature under +17 Celsius and high humidity is needed, which means that spring or autumn are most suitable (just as they are for mushroom growth). Karst sinkholes are shielded from direct sunlight; they remain humid on the inside, and this is a good environment for fungal spores, which otherwise would be unable to spread further along the surface. It takes three weeks for the system to settle. If the conditions are not suitable during this period, the spores may not settle and fail to grow. The technology is very simple. Even if something goes wrong, the process can be repeated. When all the conditions are favorable, the resulting material can handle forces of up to 40 MPa, which equals a healthy and durable material.

‘Over the course of the experiment I tried more than 20 different variations. I changed the amount of water, spores, added dolomite powder or ash, and eventually, determined the right proportions,’ Anna explained.

All in all, I worked on the project from February to May 2019. I consulted with a biomimetics expert and sought out an expert biologist

But Anna’s research turned out to be too specific: nobody could give her specific answers and suggest solutions, so she had to carry out all the experiments herself. This was not easy, but her mother and grandfather are chemistry professors, so she talked with them about calcite mineralization, read academic papers, and chose the materials herself.

The Result

In her experiment, Anna Budnikova used an area outside of the city, away from residential areas. Generally, however, karst sinkholes form right in Kazan’s city center, next to its Kremlin walls. Before using this technology on the city level, long additional tests with special equipment will be needed.

As a result of the study, the researcher determined that fungal spores help reinforce karst sinkholes and prevent them from spreading, and that they can be used later as city water reservoirs. After reinforcement, they can be filled with the same concrete, such as that used for roadways, where sinkholes absolutely must be repaired, but with the use of different technology. The architectural community is willing to work with the sinkholes as a real architectural object.  Sinkholes can lead not only to gaping holes, but to complex systems of caves, such as in China, where sinkhole-formed caves are a UNESCO world heritage site.

Professional Community Acknowledgement

In June 2019, Anna Budnikova and Elena Mitrofanova presented their study ‘MYCOKARST: A New Generation of Self-Healing Urban Materials Based on Fungal Spores’ at the annual two-day Biodesign Challenge summit in New York.

Biodesign Challenge is an international university competition organized by Genspace NYC. It offers university students the opportunity to envision future applications of biotechnology in a competition that highlights student work. This year, HSE University took part in it for the first time. A total of 500 students from 34 international universities took part in the competition. ‘Our project was more related to architecture, while the competition supports various projects related to ecology, transportation, biotechnology implementation, urbanism and commercial design,’ said Elena Mitrofanova.

In the competition finals, which took place at the New York Museum of Modern Art (MoMA), HSE University surpassed Harvard, the University of California, and Columbia, and Anna Budnikova won the Outstanding Science Award. ‘Everyone praised my project,’ says Anna. ‘But it somewhat lacked a consideration of economic aspects; this is better dealt with at a different stage of the project’s development. I presented it not as a ready-made product, but as a concept, which is relevant for architecture and can potentially be of interest’.

After Anna’s competition victory in the U.S., MYCOKARST was presented at the Moscow Urban Forum 'Quality of Life. Projects for a Better City’ at Zaryadye Park. The ‘Prototyping Future Cities’ graduates met and discussed their research with Rustam Minnikhanov, president of the Republic of Tatarstan; Natalia Fishman-Bekmambetov, advisor to the president of the Republic of Tatarstan; and Marat Khusnullin, vice-mayor of Moscow.

Receiving a Patent and Their Own Architectural Bureau

While discussing the future of the project, Anna said that she would like to publish her findings in a scientific journal, and that this in turn would help her in applying to a PhD programme.

I am going to apply to PhD programmes in a year. First, I would like to work at an architectural bureau that is open to innovation. I’ll probably even open one myself, otherwise what have I been studying all this for?

The next step is getting a patent for the technology, which can already be used to repair karst sinkholes. ‘Researchers from Binghamton University even wrote that they are the only ones who use fungal spores for self-healing materials,’ says Anna, ‘They have been investigating this for about 20 years but have only published papers about it in the recent years. I wrote them about my research and offered to cooperate, but they didn’t respond. I believe collaborations are useful, so I’ll probably join some other laboratories in this research, although I don’t know yet who deals with it, besides Shukhov Lab and Skoltech’.

The HSE Master’s Programme ‘Prototyping Future Cities’ is now accepting applications.

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