For most of us, when we think of road and bridge construction it’s usually when we are being delayed by a work zone or when we resign ourselves to driving through the smaller potholes to avoid being swallowed up by the bigger potholes. When we do think about road and bridge construction, the terms “new innovations” and “cutting edge technology” probably never cross our minds.
Asphalt road construction hasn’t changed that much in the past 100+ years. That could all change if some of these new technologies prove viable of the next few years.
In as little as three years, the city of Rotterdam in the Netherlands could see roads paved with plastic instead of asphalt. KWS Infra, a division of VolkerWessels, is working to develop PlasticRoad, modular road sections made of recycled plastic and the city is considering piloting the new technology once it’s fully developed. Still in the conceptual stage, the modular sections, made of 100% recycled material, would be manufactured in a factory and then transported and assembled on-site.
VolkerWessels claims that their PlasticRoad technology can be installed in a fraction of the time it takes to build a road using traditional asphalt. They also state that this new road surface will last three times longer than asphalt, require less maintenance and have to ability to withstand temperatures ranging from -40° to 176° Fahrenheit.
The lightweight road sections would feature a hollow core that could be used to run electrical and telecommunication cables, sewer and water pipes and drainage. That might prove problematic when it comes time to make repairs or replace a broken pipe for instance since it appears the whole section of road would have to be removed. A smarter option would be to build raceways alongside the shoulder of the plastic road with access points for repairs or new installation.
Of course, recycling plastic waste into roads isn’t an entirely new concept. Plastic has been used as a partial substitute for bitumen in some road projects in India for over a decade. The process involves melting shredded waste plastic and mixing it with hot aggregate to get plastic coated aggregate which is then mixed with bitumen to pave roads.
3D Printed Bridges
MX3D, a research and development startup in the Netherlands, is working on technology which will enable them to 3D print a 24-foot long pedestrian bridge over a canal in Amsterdam in 2017. Starting on opposite banks of a yet-to-be identified canal, at least two 6-axis industrial robots will begin printing the bridge using an additive printing technology similar to welding. A new steel composite developed at Delft University of Technology to print the bridge by adding layer after layer of molten steel on top of each other to form the structure. As the structure is being printed, the robots will travel across the printed portions, eventually meeting in the middle upon completion.
The bridge is being designed by Joris Laarman and MX3D is partnering with some big names in the construction industry. They are teaming up with Autodesk to develop software that will allow the printing robots to build the bridge autonomously and adapt to real-time changes like fluctuations in temperatures. They are also teaming up with Heijmans, a technology-driven construction and engineering firm, to build the bridge. Heijmans is also part of a team working to develop solar noise barriers for roads and highways.
If all goes according to plan, the printing robots will be turned on and left alone to do their work. In two months’ time, they will have completed the world’s first 3D printed bridge. The footbridge will be able to handle the same kind of traffic and loads that traditionally built pedestrian bridges experience in Amsterdam.
Self-Healing Concrete & Asphalt
A large amount of research on self-healing concrete and asphalt is taking place across the world. Various methods are being tested, but the most promising methods involve embedding concrete with a substance that will be released when the concrete cracks. Once released, the substance reacts with either the material in the concrete or the carbon dioxide and moisture in the atmosphere to form a substance that fills the crack and hardens.
Delft University of Technology, which we mentioned earlier, is working with dormant bacteria spores. When the spores are exposed to water, they become active and begin feeding on calcium lactate, consuming oxygen in the process. When the oxygen is removed the calcium lactate converts to limestone which hardens and seals the cracks. Another methods being tested include using glass capillaries filled with a healing agent and micro-encapsulated sodium silicate.
Erik Schlangen, another researcher at Delft, has been working for the past several years to create a self-healing asphalt. His method involves adding small steel wool fibers to the porous asphalt concrete mix to make the pavement electrically conductive. Induction heating is applied to the electrically conductive asphalt to heal the cracks.
These ideas may seem fanciful now, but they could lead to better road infrastructure in the future. Until flying cars hit the market, I’m willing to entertain any idea that means roads and bridges being delivered faster and lasting longer than what is currently available.