America’s aging roads, bridges, and transit systems are deteriorating. The American Society of Civil Engineers gave our infrastructure a “D” grade point average in a 2009 Report Card, and estimates that we’ll need $2.2 trillion over five years to improve it.
Some of that money will be used to create smarter, more durable materials, and diagnostic approaches like those Polytechnic Institute of NYU civil engineering professors Drs. Masoud Ghandehari and Weihua Jin are helping to develop. The two are working with concrete — the most-used building material on earth — that will have the smarts to self-detect chemical signs of degradation far in advance of physical symptoms, such as cracks that compromise the integrity and safety of a structure.
Dr. Ghandehari is the principal investigator along with co-PIs Dr. Jin and Dr. Christian Brückner, a University of Connecticut associate professor of chemistry, of a research project that the National Science Foundation recently awarded $400,000 to. The project’s primary goal is to improve the fundamental understanding of a chemical reaction between cement and silica-based aggregates (the building blocks of concrete). The reaction, known as the alkali-aggregate/alkali-silica reaction, or ASR, is a major contributor to the premature weakening of concrete structures worldwide.
To understand ASR, the research team is creating molecular sensors that they will add to concrete mixtures. When the mixtures have hardened, they will use imaging devices to collect data from the molecules that will tell them about the chemical changes occurring in the concrete as it is subjected to simulated outdoor conditions. The team’s approach will allow it to noninvasively collect precise data that could help material scientists create stronger, more-resilient concrete for new construction and remediation and preventative admixtures that could extend the life of existing structures.
The sensor molecules will have a life beyond these experiments. Dr. Ghandehari expects that the team’s research will lead to a commercial application for “smart” concrete. He likens its ability to monitor how well a structure ages to the tests that monitor human health.
“Medical advances have made it possible to detect certain types of cancer earlier and earlier. Our sensors will be able to do the same thing for the roads we drive on, the bridges we cross, and the buildings we live and work in,” he says. “And like cancer diagnostics, we’ll know at what stage the concrete degradation is at, and will be able to design an effective treatment plan.”
The grant supporting the team’s research is part of an NSF program that targets interdisciplinary research. Dr. Ghandehari notes that the funding will bring together students in NYU-Poly’s civil engineering department and chemistry students at the University of Connecticut. He points out that the origins of the research itself cross disciplines. Almost 10 years ago, Dr. Ghandehari and Dr. Peter Spellane, a New York City College of Technology chemistry professor, shared ideas about how chemical signs of concrete degradation could be detected. And in more recent years, he conducted research with another colleague, Dr. Gamal Khalil, a Unviersity of Washington chemistry researcher, on developing sensor molecules to detect gas leaks.
“Having conversations with people outside your realm leads to these breakthroughs,” he says. “They don’t happen otherwise.”