Induction heating for closing cracks in asphalt concrete

Lead Research Organisation: University of Nottingham
Department Name: Faculty of Engineering


Asphalt pavements are the most commonly road pavements in the UK. Preserving them in a proper state fundamentally affects the economy and quality of life. However, their surveillance and maintenance are cost and time intensive, and asphalt concrete still has to be replaced after 15 years of use. Applying induction heating into the road could make pavements last much longer by stimulating the asphalt`s property of self-healing. Experimental results have found that a crack can be fully induction-healed, for at least 5 times. The efficiency of self-healing, however, depends on the temperature of the material and the temperature should be concentrated in the cracks alone. Thus, the challenge of this research is to discover how to apply energy only locally into the cracks without dispersing energy into undesired spaces. With this purpose, experimental and mathematical models of asphalt concrete self-healing under induction heating will be developed.
This research will serve to understand the relationships between induction heating, the particles used to heat the mixture, the heat flow through asphalt concrete and its effect on asphalt self-healing. We will discover the type of particles, intensities and frequencies of induction heating which are more appropriate for healing, how to concentrate the heat in the damaged areas and the relationship between the amount of energy induced and the healing of asphalt concrete.

Planned Impact

In the short term, results of this project will make a major impact in the understanding of engineered systems for asphalt self-healing.
In the medium term, results of this project will have a major impact in the way in which asphalt roads are built and maintained, as we are in the path of creating a pavement that can potentially survive 5 times longer, at a minimum extra cost.
In the long term, results of this project will have a major impact in the pavement construction industry. Asphalt self-healing has the potential to become a disruptive technology in pavements maintenance. Results of this project will also have a major impact in society, as traffic jams due to maintenance works will almost disappear. Accidents due to the bad conditions of the road will also be reduced. Less fuel will be used by vehicles in the roads.
Major beneficiaries will be: policy makers and maintenance funders, including the Highways Agency, the Department for Transport and Local Government; the wider public, through safer roads, reduced travel times and lower costs. In addition, a completely new industrial market, pavement healing, may open.
Whilst the focus of this project is on asphaltic materials, the approach has other applications, such healing thermoplastic polymers or welding polymers.
In addition, international industries will be targeted through presentation of research results at various international conferences. Moreover, results will be targeted for publication in peer-reviewed journals. These international publications are targeted to a public composed of industries and researchers.
Furthermore, the Nottingham Asphalt Research Consortium (NARC) will provide access to a wide range of industrial organisations (such as Aggregate Industries, Bitumen Industries and Pavement Industries). The progresses of this research will be presented in the different research meetings that take place every year.
Moreover, economic and industrial beneficiaries will be updated with the results through publication of research at specialized journals, such as the Pavior Magazine, or the New Civil Engineer Journal. Results will be presented at national events, such as the conference UK Transport, organized by the Institution of Civil Engineering (ICE), which will be held in London in 2015 or 2016, where a high number of industrial members will be present.
Societal beneficiaries will be informed about asphalt self-healing through press notes into media, such as the Metro newspaper. The PI has done this before, in the newspapers Blick am Abend and 20 Minutes, in Switzerland, gaining a great attention by the public and by local industries. Additionally, research will be presented at the UCAS Open Days of the University. Poster and video displays will be created to highline the research and implications of the work to society.
As, from the results generated in this project there may be particular applications of interest for the asphalt industry, the Business Development Manager of the Infrastructure and Geomatics Division at the UoN will keep a constant overview of the research, both during and after the project has finished, to assess if there is Intellectual Property that should be protected.
The impact activities will be taken by the PI. The PI has experience working as a pavement engineer for more than 8 years and he has been researching asphalt self-healing for more than 5 years. He will use his international contacts to ensure a good dissemination of results. In addition, he works for the Nottingham Transportation Engineering Centre (NTEC), which is the main co-ordinator of the NARC consortium and has extensive industry and administration contacts.


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Description We have found that the asphalt self-healing obtained using induction differs from the natural healing that happens in nature. Asphalt self-healing happens due to the different heating rates, and thermal expansion coefficients of the bitumen used. These values do not depend on the source or type of bitumen.

We have also found that asphalt mixture does not heal differently depending on the air voids content and their connectivity level.

Moreover, we have compared infrared, induction, and microwave heating for improving asphalt self-healing.

When we finish this project, we expect to have a much more clear understanding of the factors influencing asphalt self-healing.

With this grant we have published 4 articles on asphalt self-healing. In addition, we have built an experimental set-up that is currently being used to develop pavements that can collect energy from the solar heating. These experiments have produced 3 extra publications.

We have attended the ISAP 2016 Symposium, From Molecules to Innovative Pavements, USA, and to the 4th International CEW event on Functional Pavement Design, the Nethelands. We presented the research in Nantes, France, at a RILEM conference and got our article selected for publication. We have submitted an article to the EATA (European Asphalt Transport Association) 2017 conference, in Switzerland that has been accepted for presentation.
Exploitation Route We have discovered that the main factor influencing self-healing is the thermal expansion of the different components in the mixture that promote the movement of bitumen through the cracks. We have found that the thermal expansion is constant for every type of bitumen and that asphalt mixture composition does not have an influence on asphalt self-healing by using induction heating. This is excellent because we have eliminated the need for optimising the road materials. We have found that the cost of the technology is higher than expected and in the future we will work to reduce it.

We have used the project to explain asphalt self-healing. Now we know exactly where the technology can take us. We have used what we have learned to initiate a new research on asphalt self-healing using capsules.

My citation level has multiplied by 3. Tarmac built a road using this technology.

Moreover, we have organised research collaborations with the University of Bio Bio, in Chile, Elacig in Turkey and the Chongqing Jiaotong University, in China. We have exported the technology to these places. We submitted several proposals to continue this topic, although so far we were not successful being granted.

The next step in the research is to reduce the price of the materials, by using recycled elements, such as steel slag and recycled asphalt mixture.
Sectors Construction,Transport

Description The main finding from this grant outside academia is that we discovered that steel slag heats via induction energy. This was a very exciting coincidence, as there are many pavements already built that use steel slag as aggregates, and these pavements have been in the road for many years, which means they are already damaged. For this reason, in the next months we will be working together with Tarmac, a company, to characterise the heating of the existing pavements with steel slag and observe their damage recovery properties. Actualisation (03/02/2017): Tarmac Ltd has built a roundabout in Rutland. In addition, this award had a lot of influence on further projects that were acquired. In 2018, I have been 3 times in the TV, BBC showing the research on asphalt self-healing.
First Year Of Impact 2016
Sector Construction,Transport
Impact Types Societal,Economic,Policy & public services

Description ERA-Net Infravation
Amount € 226,059 (EUR)
Organisation Forum of European National Highway Research Laboratories (FEHRL) 
Sector Public
Country Global
Start 10/2015 
End 07/2017
Description Highways England internal funding for research
Amount £37,000 (GBP)
Organisation Department of Transport 
Department Highways Agency
Sector Public
Country United Kingdom
Start 04/2017 
End 11/2017
Description ITN SAFERUP!
Amount € 4,500,000 (EUR)
Funding ID 765057 
Organisation European Commission H2020 
Sector Public
Country Belgium
Start 03/2018 
End 02/2022
Description Partnership with University of Bio Bio, Chile 
Organisation University of Kuopio
Country Finland 
Sector Academic/University 
PI Contribution We tested a new range of materials for induction heating and wrote a research article
Collaborator Contribution The partners built materials, came to the UK, tested the materials in our laboratory, and reported the results for writing a research article.
Impact An article, has been submitted in January 2016 to Materials and Design: J. Norambuena-Contreras, A. Garcia, 2016, Differences between asphalt self-healing induced by microwave and induction heating, Materials and Design (Submitted)
Start Year 2015
Description University of Cantabria. Visit of Pedro Lastra 
Organisation University of Cantabria
Country Spain 
Sector Academic/University 
PI Contribution We provided the laboratory, the concept and the ideas to work on asphalt induction heating.
Collaborator Contribution Pedro Lastra visited our laboratory for 3 months and contributed enormously to the progress of the tests. From his results we expect three journal articles.
Impact 3 articles now in the writing process (03/02/2016)
Start Year 2015
Description Visiting professor from Chonqing University. Prof He Liang 
Organisation Chongqing University
Country China 
Sector Academic/University 
PI Contribution We worked together with Professor Liang to introduce him on the asphalt induction heating technology.
Collaborator Contribution The partner helped in the laboratory testing, sorting materials, and discussing the tests to be done.
Impact A proposal was submitted to the Newton Fund to continue the collaboration.
Start Year 2015
Description Annual Symposium Smarter Roads 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Professional Practitioners
Results and Impact Annual Sympossium of the East Midlands Region section of the Chartered Institution of Highways and Transportation. Presentation of the work on asphalt self-healing to local and regional practicioners.
Year(s) Of Engagement Activity 2016
Description Chinese European Workshop 2016 (the Netherlands) 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact The conference will be in the summer of 2016, that is why there is not yet ouput.
Year(s) Of Engagement Activity 2016
Description ISAP symposium, International Society for Asphalt Pavements (Wyoming) 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact The conference will take place in the Summer 2016. 2 articles have been submitted. That is the reason why there is not yet an impact
Year(s) Of Engagement Activity 2016