The beauty of concrete as a construction material is its strength under compression, but over time, with exposure to sun and rain, traditional concrete begins to break down. While reinforcing fiberglass, steel rods, and other additives have helped to make concrete more resilient, even these tend to break down, or worse, crack.
Repairs, unfortunately, are only temporary, and don’t really solve the problem. In any case, repair or replacement are both expensive and time-consuming.
A new building material, developed by University of Michigan’s Advanced Civil Engineering Materials Research Lab, aims to change the face of infrastructure. The new self-healing concrete mix, instead of using the sand and gravel found in traditional concrete mixes, uses microfibers.
The fibers bend instead of break, and if cracks form, they are on the order of microns wide. Where it gets interesting though, is what happens when the cracks do form.
“When these tiny cracks form, the dried concrete absorbs moisture from the air,” write the researchers. “When it does this, the concrete in the crack becomes softer and eventually ‘grows’ until the crack is filled in. At the same time, calcium ions within the crack absorb the moisture along with carbon dioxide from the air.
This reaction forms a calcium carbonate material that is similar to the material found in seashells. This regrowth and solidifying of calcium carbonate renews the strength of the cracked concrete.”
Self-healing concrete technology, if not economical to install, would certainly make constant repair and replacement a thing of the past, and thousands of dollars in maintenance could be put to better use elsewhere.