Sensors developed by Purdue University engineers have been embedded into Indiana highways to more precisely determine when the concrete pavement is ready to handle heavy truck traffic, as part of a collaboration with the Indiana Department of Transportation. The data will provide a new recommendation for when roads should reopen following a construction project.
The sensors were developed by a research team led by Luna Lu, an associate professor in Purdue’s Lyles School of Civil Engineering. The sensors track concrete strength development in real time through measurements of hydration, stiffness, compressive strength and other properties of concrete. After testing, the Indiana DOT will enable the sensors to be permanently embedded in the highways and continuously inform contractors on concrete distress.
“Fast-paced construction schedules can often expose concrete to traffic too early, causing premature failure,” said Lu in an article on Purdue University’s website. “Our data will help us to recommend the best time for traffic to open and benefit taxpayers.”
A sensor patch is embedded on the concrete surface. Wires connect the patch to a measurement system. Using a so-called piezoelectric effect, the setup converts electrical energy to mechanical energy, exciting the sensor and vibrating the concrete to detect its stiffness. Mechanical energy is then converted back to electrical energy. The sensor measures the opposition of concrete to the flow of electricity through a read-out of electrical data, providing accurate measurements of many concrete properties at once.
The sensors are protected from corrosion and not easily crushed by construction equipment. The setup also allows data to be collected for years after the concrete is laid down. In contrast, conventional laboratory testing methods collect data for only 28 days, leaving gaps in understanding of how concrete strengthens after that point.
“Concrete pavement patching has to achieve a certain strength level to accommodate truck traffic due to the load and pavement curling and warping," said Tommy Nantung, research manager at the INDOT Research and Development Division, in the article. "Through these sensors, a contractor will know exactly when the concrete is mature enough to accommodate heavy truck loads and the curling and warping stress."
So far, the researchers and INDOT engineers have embedded the sensors into three highways in Indiana: I-70, I-74 and I-465 near Indianapolis. The Purdue team also is working with the Federal Highway Administration on a nationwide pooled fund study to implement the technology in other states. California, Texas, Kansas and Missouri are planning to join the study
Below is a video showing the project, which is also available at https://youtu.be/LS0zXtIa2PA.