Opinion: new technology may provide a resolution to how potholes and cracks causes accidents and congestion on our roads

Potholes and cracks cause many accidents on our roads. However, a new technology called self-healing asphalt could make them and much of the major road repair work that contribute to traffic congestion a thing of past, saving billions of euros in the process.

The global road network spans 16.3 million km, including five million km in the EU. Road networks are the backbone of the global economy and governments spend a significant proportion amounts of their annual budgets building and maintaining them.

In 2014, EU governments invested a total of €53.33 billion in the development and maintenance of the EU road network. This represents half of the total EU expenditure on transport infrastructure (which also includes rail, sea, air and inland waterways). The ongoing importance of roads as a means of transportation drives the need for improved road materials and better road pavement design.

From RTÉ Archives, Tom Kelly reports for RTÉ News in 1992 on potholes in Co Longford

Introducing self-healing asphalt

A typical, modern, road system is comprised of double or triple asphalt layers which have an expected lifespan of 20 to 40 years. The focus of much research to date has been on extending the service life of roads in order to dramatically reduce the cost and disruption of road resurfacing and routine road maintenance. Self-healing asphalt technology is one such solution as it allows roads to auto-repair by embedding a self-healing system within the asphalt pavement layers that enables it to heal itself once damaged.

The drive to incorporate self-healing technology into road design is driven from the vision of the "Forever Open Road", the road that will avoid the traffic disruption caused by routine road maintenance activities. Self-healing asphalt would also reduce the environmental impact of road construction and maintenance as it could potentially double the service life of a road to between 40 and 80 years.

This would result in significant savings annually for the EU. A 50 percent reduction in major road repairs and related traffic congestion would save about €9 billion. The reduction in traffic congestion related to major road repairs would reduce energy consumption and CO2 emissions by about 30 percent and would also reduce current demand for fresh aggregates and enhance road safety.

From RTÉ Radio One's Sean O'Rourke Show, Brian O'Connell reports on the deteriorating state of our roads in the wake of Storm Emma and the Beast from the East

Tell us more about this technology

Asphalt pavement design standards typically focus on enhancing asphalt pavement performance by increasing durability and improving the load-carrying capability of the road. However, my research proposes that the future of asphalt pavement design lies not by enhancing asphalt pavement properties, but in allowing the asphalt to it to repair itself, to self-heal.

To date, research on self-healing asphalt methods has focussed on:

(i) induction/microwave heating: steel fibres, steel wool and conductive particles are added to the asphalt so when the road is damaged, healing is initiated within the asphalt by sending a current through the coil. This current causes steel fibres to heat up which heats the asphalt and softens it, allowing it to flow, close the cracks, and repair the damage. This method can be repeated whenever the road is damaged again.

Self-healing asphalt technology is truly a revolution in road construction as it wll potentially allow rapid repair of roads without the need for road closures

(ii) rejuvenation: a healing agent is added into the asphalt mix to restore the original binder properties. Road damage begins with small cracks. When these micro-crack form within the asphalt, they encounter a capsule within the self-healing asphalt. The capsule opens, releasing the healing agent which then diffuses within the asphalt softening it and allowing it to flow into and seal the crack. This approach enables the asphalt to rejuvenate and return to its original state and for this reason, is a more favourable method of self-healing.

Both methods of self-healing have been tested in relation to asphalt. This has involved developing different types of capsules and fibres for inclusion in the asphalt and then testing them to ensure they can survive the asphalt production process. Research has also found that the rejuvenation method has limited healing capacity and is slow in comparison to the induction method.

"The global road network spans 16.3 million km, including five million km in the EU"

My research at Dublin Institute of Technology, in collaboration with Professor Erik Schlangen at Delft University of Technology, seeks to develop a new hybrid asphalt self-healing method. This method will combine the best of the existing self-healing methods (induction heating and rejuvenator encapsulation) to create a method that will allow for rapid and effective asphalt pavement repair.

Self-healing asphalt technology is truly a revolution in road construction. It will potentially allow rapid repair of roads without the need for road closures and/or traffic congestion. Even better, as the technology is embedded within the road, repairs/self-healing can be carried out in full traffic flow.

This research is conducted in the Microlab at the Delft University of Technology in collaboration with Dublin Institute of Technology by a research team composed of Dr Amir Tabaković, Shi Xu, Dr. Xueyan Liu and Professor Erik Schlangen. The research is funded by EC FP7 Marie Curie Individual Fellowship Action and China Scholarship Council.


The views expressed here are those of the author and do not represent or reflect the views of RTÉ