Self-Healing Asphalt To Replace Traditional Roadway Materials

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Scientists in Switzerland and the Netherlands are developing new technologies to replace traditional roadway materials with selfhealing asphalt. Dutch researchers from Delft University of Technology have created an asphalt composition that resembles closedloop circuits and is infused with electrically conductive fibres. Meanwhile, Swiss scientists have created a method that enables iron oxide nanoparticles in surface cracks to heal the surrounding asphalt in only a matter of seconds when exposed to an alternating magnetic field. Concrete has been around since the Ancient Romans, but its durability and environmental impact have changed the material’s composition since that time. MIT researchers are even exploring the material at its atomic level to study how concrete can be fortified by additives like slag and volcanic ash.Self-healing concrete has gained traction as researchers have taken aim at finding longlasting fixes for U.S. infrastructure. Louisiana State University scientists are testing microencapsulation of chemical additives to trigger a self-healing process when concrete starts to crack.Still others are testing concrete that breaks traditional norms entirely with a composition comprising naturally grown bacteria. Researchers, also from Delft University of Technology, are infusing traditional concrete with bacteria that stays intact during mixing before dissolving and becoming activated by water seepage in cracks. Scientists’ push to develop more resilient sustainable concrete alternatives comes at an opportune time for the nation’s infrastructure. A 2017 report from the American Society of Civil Engineers gave the U.S. a D+on its Infrastructure Report Card, with roads scoring a D grade on the assessment. According to that report, one in every five miles of paved road is in poor condition, and the backlog for repairing those highways is only increasing. Smart roads can also limit surface snow and ice accumulation. Sandpoint, Idaho–based Solar Roadways offers a tile-based paving system that can be installed on top of existing road surfaces. Each hexagonal module consists of a 44-watt solar panel with integrated LED lights and heating elements protected below a high-strength tempered glass surface. Another approach involves the use of conductive concrete, which like the selfhealing asphalt described above requires the introduction of electricity to charge the road surface. In the case of a technology developed by researchers at the University of Nebraska– Lincoln, an entire road can be transformed into a heating element with 48 volts of electricity, preventing snow accumulation altogether. Such capabilities are impressive; unfortunately, conductive concrete is more than twice the price of typical road bed construction, at $300 per cubic yard versus $120, respectively. Other smart and/or self-heated roadways are also expensive. It brings us back to the original predicament because it is tough to manage road surface

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integrity considering perpetually insufficient maintenance budgets. A promising solution might be to combine the surgical use of the material innovations outlined above with predictive technologies. For example, Bob Bennett, Kansas City, Mo’s chief innovation officer, has developed a system of sensors and computer algorithms that target pothole-susceptible zones in his city. Working with Chicago-based technology firm Xaqt, Bennett installed pressure sensors within the roadbed of a heavily used 51-block area. The sensors, in addition to traffic lightmounted cameras, report real-time activity on the streets. This information is combined with an extensive collection of weather, construction, and repair history data to deliver a pothole prediction platform with 85 per cent accuracy. One of the ASCE’s recommendations is to consider a “road diet,” an approach that transforms existing roadways by “reducing the number of lanes and adding safety features”. Not only has such a practice proven to be safer for pedestrians and bicyclists, but it also may be fiscally necessary, given that there is currently more road than we can maintain.