Concrete, the most widely used material in the construction industry, has a history dating back to the Roman Empire. Now, engineers at the University of Pittsburgh are reimagining its design for the 21st century.
Concept artwork depicting a new metamaterial concrete in use on a highway. Image Credit: Amir Alavi via Midjourney
New research introduces metamaterial concrete for developing smart civil infrastructure systems. The paper published in ("Multifunctional Nanogenerator-Integrated Metamaterial Concrete Systems for Smart Civil Infrastructure"), presents a novel concept for lightweight, mechanically tunable concrete systems with integrated energy harvesting and sensing capabilities.
"Modern society has been using concrete in construction for hundreds of years, following its original creation by the ancient Romans," said Amir Alavi, assistant professor of civil and environmental engineering at Pitt and corresponding author of the study. "The massive use of concrete in our infrastructure projects calls for the development of a new generation of concrete materials that are more economical, environmentally sustainable, and offer advanced functionalities. We believe that introducing a metamaterial paradigm into the development of construction materials can achieve all these goals."
Alavi and his team have previously developed self-aware metamaterials and explored their applications in areas such as smart implants. This study introduces the use of metamaterials in creating concrete, allowing the material to be specifically designed for its purpose. Attributes such as brittleness, flexibility, and shapeability can be fine-tuned during the creation of the material, enabling builders to use less material without compromising strength or longevity.
"This project presents the first composite metamaterial concrete with super compressibility and energy harvesting capability," said Alavi. "Such lightweight and mechanically tunable concrete systems can pave the way for using concrete in various applications, such as shock-absorbing engineered materials at airports to help slow runaway planes or seismic base isolation systems."
Furthermore, the material is capable of generating electricity. While it cannot produce enough electricity to supply power to the electrical grid, the generated signal is sufficient to power roadside sensors. The electrical signals self-generated by the metamaterial concrete under mechanical excitations can also be used to monitor damage within the concrete structure or to monitor earthquakes while reducing their impact on buildings.
In the future, these smart structures may even power chips embedded within roads to assist self-driving cars in navigating on highways when GPS signals are weak or LIDAR is not functioning.
The material is composed of reinforced auxetic polymer lattices embedded in a conductive cement matrix. The composite structure induces contact-electrification between the layers when mechanically triggered. The conductive cement, enhanced with graphite powder, serves as the electrode in the system. Experimental studies show that the material can compress up to 15% under cyclic loading and produce 330 μW of power.