Cracks on roads turn into portholes that deteriorate your car, slow down your days, or even end your life. Today, it seems like bad roads in Australia are everywhere thanks in part to global warming. However, cracks, potholes, and major roadwork could soon be a forgotten past thanks to scientific breakthroughs like ‘smart asphalt’.
Scientists are developing ingenious and unconventional methods of restoring roads by improving their durability. Rather than focusing on the improvement of road strength, scientists are focusing on asphalt with the ability to heal itself once damaged.
Infrastructure repair and maintenance is a costly job, and one that causes traffic jams when road sections are closed for renovation. An American Society of Civil Engineers report on road infrastructure gave the country’s roads system a D-rating due to its poor condition and increasing rehabilitation backlog.
Roads in Europe and Australia aren’t in a better state, either, which is a problem for commuters and governments. Degrading road infrastructure leads to accidents, increased travel times, and high carbon emissions.
The primary raw material used in making roads is asphalt. Though there are many types of asphalt, the specific one used in road construction is composed of stone skeleton mixtures that are structurally sound and aggregate. The glue used to hold the bricks in place is made up of a bitumen mortar.
Once asphalt is laid on the ground surface, many forces influence it over time causing cracks to form in the mortar. Since fraying usually occurs on the surface, the adhesion force between the rocks gets tired due to both vehicles and environmental factors like rain, temperature, and ultraviolet radiation.
Adding steel fibres to asphalt ensures that once it is worn out and cracks/potholes appear, it only needs repair. Iron molecules are heated remotely by introducing a fast-changing magnetic field. Once heated by induction, the steel fibres immediately release heat to the mortar, which melts briefly. This causes the asphalt to reset to its original structure.
An induction machine is used in the repair in a process called guiding. There is little loss of energy since it travels directly between the steel fibres and mortar – where the cracks form. Additionally, the entire surface needs not be heated, only the part where cracks form. In two to three induction regimes, the lifespan of the asphalt is prolonged up to 20 years from the present 10 to 12 years.
Researchers at EMPA in Switzerland and ETH Zurich are taking a similar route but using iron oxide nanoparticles in self-healing asphalt instead of iron fibres. These nanoparticles heat up upon exposure to a magnetic field. In place of induction machines, maintenance vehicles outfitted with magnetic coils are used to introduce heat that starts the healing process. Once heat is transmitted to the bitumen, it softens and fills the cracks.
Alvaro Garcia discovered the use of the Capheal formula at the University of Nottingham. The method involves inserting sunflower oil microcapsules into asphalt, which reduce the binder’s viscosity and help the asphalt heal. Once tiny cracks appear, the microcapsules burst and soften the asphalt around them causing binding. This method fixes cracks before they grow.
Self-healing asphalt only requires minimal repairs and replacement. This means it has fewer maintenance costs as opposed to other materials currently in use. Although the cost of the first installation is 25 percent higher, it is offset by the fact that self-healing asphalt has double the lifespan of regular asphalt, which means fewer maintenance expenses in the long-run.
The asphalt mixed with steel fibres is strong and reinforces road surfaces causing fewer cracks to appear and form into portholes. This increases road durability.
There is less work required on the roads to carry out repairs since the guiding and induction process is simple and faster than any other traditional methods.
Metal oxide nanoparticles are faster and more efficient in self-healing compared to iron fibres because the later takes longer to heat up, which slows down the entire process.
Apart from self-repairing roads, experts are predicting that roads of the future will be able to receive information according to Delft University’s Erik Schlangen based in the Netherlands. As a result, charging electric cars while driving or when waiting in traffic is theoretically possible.
The reliance on roads is as rampant and essential today as it was 100 years ago. Since roads keep expanding and vehicles continue to pound them, the relevance of self-healing asphalt roads cannot be overstressed. They lead to fewer costs, maintenance, roadwork, and no potholes.By Jason Hook
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