What is Self-Healing Concrete?

January 08, 2019
Author: Ben Halverson
Organization: Lorman Education Service

Invented over 2,000 years ago, concrete has consistently remained one of the most commonly used building materials. It is solid, durable, easy to mass produce, easy to maintain, as well as cheap. The downside? Concrete is susceptible to cracks that can compromise the entire structure of a building. If cracks aren't caught and filled while they're small, it can lead to catastrophic damages.

However, it seems the days of cracked concrete may be coming to an end. Scientists have revolutionized the industry with the development of self-healing concrete.
 
Everything You Need to Know About Self Healing Concrete

Over the years, scientists and engineers around the globe have experimented with various healing agents to perfect self healing concrete. Some of these healing agents have been bacteria, sodium silicate, and even fungus.
 
Bacteria-Based Self Healing Concrete

Self healing concrete was invented by Henk Jonkers, a microbiologist and professor at Delft University of Technology in the Netherlands. Jonkers began developing self healing concrete in 2006. After three years of experimenting, he found the perfect healing agent - bacillus.

"You need bacteria that can survive the harsh environment of concrete," Jonkers said in an interview with CNN. "It's a rock-like, stone-like material, very dry."

Bacillus is a perfect match for the job. The bacteria will thrive in the high-alkaline conditions of concrete and produce spores that can live up to four years without any food or oxygen.

Jonkers finalized his creation by adding calcium lactate to the limestone concrete mixture in order to feed the bacillus so that they can produce limestone to repair cracks in the concrete.

"It is combining nature with construction materials," Jonkers said. "Nature is supplying us a lot of functionality for free. In this case, limestone-producing bacteria."

Sodium Silicate-Based Self Healing Concrete

An engineering student with the University of Rhode Island, Michelle Pelletier, created a similar self healing concrete in collaboration with Arijit Bose, a professor of chemical engineering at her university. Their self healing concrete is inexpensive, utilizing a micro-encapsulated sodium silicate healing agent, according to an interview with Pelletier on New Atlas.

As cracks form in the concrete, these capsules rupture and release the sodium silicate. The healing agent reacts with the calcium hydroxide within the concrete, forming a calcium-silica-hydrate gel that repairs the crack and hardens in about a week.

Fungus-Based Self Healing Concrete

Taking inspiration from our own bodily functions, Ning Zhang of Rutgers University, as well as Congrui Jin, Guangwen Zhou and David Davies of New York's Binghamton University created a fungus-based self healing concrete, according to New Atlas.

Their concrete relies on spores from the Trichoderma reesei fungus. These spores remain dormant until the first cracks begin to emerge, at which that point they begin to fill these areas in.

The Future of Self Healing Concrete

As you can imagine, self healing concrete is a total game-changer. It gives us the ability to construct buildings without worrying about damages or intensive maintenance. Not only will structures benefit from self healing concrete, they are a wonderful solution for sidewalks. Smooth pavement can be laid down in cities and suburbs, without having to worry about wear and tear.

However, self healing concrete is still in the midst of being perfected. While it may be hard to get your hands on some self healing concrete at the moment, you can expect it to dominate the industry within the next few years. In the meantime, there are recipes to create your own self healing concrete online.

One of the most commonly used building materials is once again revolutionizing how we build and design our infrastructures. With self healing concrete, wear and tear will no longer be a worry for concrete buildings or sidewalks. Although it is still in development, scientists are taking many different approaches to perfecting self healing concrete. Some of these healing agents have been created using bacteria, sodium silicate, as well as fungus.

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