Self-Healing Concrete Pavement: Extending Pavement Life
Concrete pavements are already well-known for their resilience and long lifespan. However, an emerging technology promises to improve upon these characteristics even more. The key? An enzyme that promotes the growth of calcium carbonate crystals to fill cracks as they develop.
Although still in the research phase and a few years from testing in the field, lab results lab have demonstrated self-healing samples with millimeter-scale flaws heal within 24 hours. This is significantly faster than other methods, such as the use of bacteria, which requires a minimum of 28 days for strength recovery of microscale cracks.
“The Carbonic Anhydrase (CA) enzyme can be added to the concrete mix to create a self-healing material to apply to cracked concrete or mixed into fresh concrete to create a pavement that can heal itself over time,” says Jessica A. Rosewitz, P.E., Ph.D., Assistant Teaching Professor of Civil, Environmental and Architectural Engineering at Worcester Polytechnic Institute and co-author of the research article describing the process. “The CA enzyme uses CO2 and a calcium source to create calcium carbonate, our healing material. When a crack forms in enzymatic concrete, exposing the enzyme to CO2 in the air triggers the growth of a new matrix that fills the crack.”
The process is also environmentally sound. “The enzyme absorbs CO2 to heal the pavement, which reduces greenhouse gases,” Rosewitz adds.
Healing small cracks as they develop prevents them from growing into larger cracks or faults that affect the pavement’s strength, water tightness and durability of the pavement, which reduces maintenance requirements and extends the concrete pavement’s already long lifespan.