Imagine concrete healing its own cracks like human skin recovering from a cut. Concrete that fixes itself is the vision behind the latest research of Congrui Grace Jin in Materials Today Communications.

Addressing one of the most persistent and expensive problems in construction, Jin, an assistant professor in the engineering technology and industrial distribution department at Texas A&M University, has taken inspiration from nature to develop a synthetic lichen system to enable concrete to self-repair.

Concrete is the most widely used building material on Earth, yet it suffers from the dangerous flaw of cracking easily, showing how concrete that fixes itself could be an incredible breakthrough. These cracks, big or small, can lead to catastrophic structural failure, as witnessed in the collapse of a building, bridge, or highway.

The key to overcoming this critical challenge lies in understanding how concrete forms and how to exploit that process. Concrete is made by mixing crushed stone and sand with powdered clay and limestone. When water is added, the combination hardens through a chemical reaction called hydration. Once set, it becomes strong enough to support everything from 18-wheelers crossing bridges to people living in towering skyscrapers. However, natural forces like freeze-thaw cycles, drying shrinkage, and heavy loads cause cracks. Even those barely visible to the naked eye can allow liquids and gasses to reach embedded steel reinforcements, causing corrosion and weakening structures.

Discovering cracks before they endanger lives is a high-stakes and costly challenge, with the US annually spending tens of billions of dollars repairing concrete infrastructure. Locating cracks in bridges and highways that are constantly in use is especially difficult.

“Microbe-mediated self-healing concrete has been extensively investigated for more than three decades,” says Jin, “but it still suffers from one important limitation—none of the current self-healing approaches are fully autonomous since they require an external supply of nutrients for the healing agents to continuously produce repair materials.”

For example, after inspectors go through the laborious process of locating a crack, they may then have to inject or spray nutrients into the crack, which is not practical.

Read the full article about concrete that fixes itself at Futurity.