The cases against concrete and its environmental impacts are prevalent in the AEC community. As a result, numerous attempts and research initiatives have been made to help mitigate the material's environmental impact. Research from firms like Snøhetta and their net-zero concrete to companies like CarbonCure and CarbonBuilt (formerly CO2Concrete) and their carbon-sequestering cement products are a few examples of concrete change — no pun intended. 

Recently, researchers from Worcester Polytechnic Institute (WPI), lead by associate professor of Civil and Environmental Engineering Nima Rahbar, have developed a new method for producing concrete with "self-healing" capabilities to strengthen the durability of concrete structures.

The research paper, titled "An Enzymatic Self-Healing Cementitious Material," was published in Applied Materials Today, a peer-reviewed journal focused on cutting-edge applications of novel materials. Co-authors were Suzanne Scarlata, professor of Chemistry & Biochemistry; Jessica Rosewitz, former PhD student and now an adjunct instructor of Engineering; and PhD student Shuai Wang.

Some may recall the work of Henk Jonkers, a microbiologist from the Delft University of Technology, and his work on self-healing concrete. While Rahbar and Jonkers' methods help concrete rejuvenate and heal itself, Jonkers used concrete laden with limestone-producing bacteria and calcium lactate to help the concrete self-seal. Nima Rahbar and the research team at WPI used an enzyme found in red blood cells that allows concrete to self-heal, making it "four times more durable than traditional concrete."

Professor Rahbar explains: "The global use of concrete is ubiquitous. If tiny cracks could automatically be repaired when they first start, they won't turn into bigger problems that need repair or replacement." He continues to share with the Institution's Science Writer in Residence Sharon Gaudin: "It sounds sci-fi, but it's a real solution to a significant problem in the construction industry." 

Lab demo of concrete healing itself. Video courtesy of Worcester Polytechnic Institute (WPI)

According to Rahbar, the enzyme "automatically reacts with atmospheric carbon dioxide (CO2) to create calcium carbonate crystals, which mimic concrete in structure, strength, and other properties, and can fill cracks before they cause structural problems."

Rahbar and his team further explained to Gaudin that their three-pronged approach consisted of a "concrete mix that, when used to build a structure, will autonomously mend small cracks that form; a mixture that can induce self-healing in larger cracks or holes; and a process that can be applied to traditional concrete to mend cracks." With this research, Rahbar predicts this application of self-healing concrete will not only retain the strength, durability, and water tightness of concrete but can also extend the life span of applied concrete structures from "20 years, for example, to 80 years."

Learn more about this research here.