Researchers have found a fungus which when added to concrete can help it repair its own cracks.
There are many concrete structures across the world suffering from serious deterioration. Cracks are very common due to various chemical and physical phenomena that occur during everyday use. Concrete shrinks as it dries, which can cause cracks. It can crack when there’s movement underneath or thanks to freeze/thaw cycles over the course of the seasons. Simply putting too much weight on it can cause fractures. Even worse, the steel bars embedded in concrete as reinforcement can corrode over time.
Very tiny cracks can be quite harmful because they provide an easy route in for liquids and gasses – and the harmful substances they might contain. For instance, micro-cracks can allow water and oxygen to infiltrate and then corrode the steel, leading to structural failure. Even a slender breach just the width of a hair can allow enough water in to undermine the concrete’s integrity.
But continuous maintenance and repair work is difficult because it usually requires an enormous amount of labor and investment.
Inspired by the ability of the human body to heal itself of cuts, bruises and broken bones researchers at Binghamton University, State University of New York set out to find a solution for ailing concrete. They screened a number of species of fungi in order to find one that could withstand the harsh conditions in concrete.
They identified suitable fungal spores, which could be added together with nutrients, during the initial mixing process when building a new concrete structure. When the inevitable cracking occurs and water finds its way in, the dormant fungal spores will germinate.
They found that as the spores of T. reesei, an eco-friendly and non-pathogenic fungus, grow, they’ll work as a catalyst within the calcium-rich conditions of the concrete to promote precipitation of calcium carbonate crystals. These mineral deposits can fill in the cracks. When the cracks are completely caulked and no more water can enter, the fungi will again form spores. If cracks form again and environmental conditions become favourable, the spores could wake up and repeat the process
T.reesei has a long history of safe use in industrial-scale production of carbohydrase enzymes, such as cellulase, which plays an important role in fermentation processes during winemaking.