Repairing roads is a highly expensive and arduous process that takes many days, sometimes causing traffic jams or detours. But what if roads could repair themselves using a new type of concrete?

That is what is being proposed by Purdue University researchers creating intelligent concrete that would allow paved bridges and highways to reveal more accurately when roads need repairs and come equipped with materials that respond to potential damage.

According to a 2020 report by the American Road and Transportation Builders Association, more than one-third of U.S. bridges need repair work. Intelligent concrete could help prevent cracks caused by reopening roads too soon or having to replace the concrete, which takes up time and causes traffic.

“We look at how we can address problems in infrastructure using materials and sensors that harness artificial intelligence and big data,” said Luna Lu, an associate professor in Purdue’s Lyles School of Civil Engineering. “The idea is to make infrastructure adaptive, sustainable and resilient.”

Lu worked with the Indiana Department of Transportation in 2019 to embed Purdue-developed sensors into three highways — Interstate 465 near Indianapolis, I-70 near Plainfield and I-74 near Batesville.

These sensors help municipalities determine when to open a roadway to traffic after a patching or new pavement project and it continuously tracks concrete development. Researchers are working with the Federal Highway Administration to implement these concrete sensors in other states.

While this allows the concrete to "talk" to government officials, simultaneously, Lu and her team are developing a way that the concrete could also repair itself.

So-called “self-healing concrete” could be useful in winter when concrete freezes and then thaws in cycles, which expands or cracks the concrete. These cracks lead to fissures over the course of several winters.

Purdue is researching different types of porous, sand-like materials called internal curing agents to mix into the concrete so that when a crack appears, the agents absorb water and feed it into chemical reactions. These reactions then produce solid substances that seal off the crack. The material also prevents water from seeping into the concrete or corroding the rebar or steel reinforcement.

“By using these self-healing materials, we can make infrastructure adaptive to temperature change,” Lu said. “Traffic is always directional. Conventional thinking is to add extra lanes, but artificial intelligence and big data could identify an underused lane and shift traffic into that direction. We’re developing technology that would allow for better control of traffic without adding extra lanes.”

The next steps include bringing together additional researchers and finding resources to enable this type of infrastructure on a large scale. Lu and her team are also working with several state transportation departments to establish the first Midwest intelligent infrastructure consortium to further develop intelligent concrete.

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