The extension and optimisation of the lifetime of roads is crucial to ensure the free movement of people and goods. However, providing a reliable performance of the network is becoming increasingly difficult. More investments will be needed in the future to cope with new challenges: ageing infrastructure, higher traffic demand, climate change and an increase of heavy goods vehicles.
The number of maintenance and rehabilitation interventions will become gradually more frequent in order to repair, amongst others, cracks appearing on the road surface. Repairing asphalt pavements by traditional methods can indeed extend the life service for the network but at a high cost: first of all, it requires public administrations increasing funding; second, it entails an an environmental impact due to the large amount of natural resources, and finally, it limits the mobility of people and goods.
Approximately 1% of EU GDP is lost due to disturbances in the transport flow, part of which is on account of repair, maintenance, retrofitting and revamping. In addition, natural resources are also highly used to extend the lifetime of any road. A recent study from the OECD highlighted the high number of natural aggregates used during road construction (i.e. 10.000 m3 per Km in a two-lane road). Further research from the asphalt sector has unveiled that approximately 158 tons of fuel are needed per Km of road.
In this context, research in more efficient and sustainable road maintenance techniques will contribute to extending the lifetime of the network, optimise traffic flow and ensure minimum performance in terms of safety and quality.
Induction-heating of asphalt mixture is a preventive and non-intrusive maintenance technique used to accelerate the self-healing properties of road pavements, from the current days needed to heal micro-cracks to a few seconds. Preliminary tests have shown that the lifetime of asphalt pavements could be potentially extended by 30% with every healing treatment. The objective of HEALROAD project is to underpin industrialization of this technology. With this purpose, asphalt mixtures that can be induction heated will be developed, optimized and demonstrated. It is expected that this technique will postpone several years the need of major maintenance of wearing courses, improving the best value for money and resource efficiency. The project aims to:
- Understand the main chemical and rheological factors influencing the movement of bitumen through cracks in order to identify the most suitable bitumen for this application.
- Optimize from the technical, economic and environmental point of view the parameters that most influence the induction heating of the asphalt mixture: magnetic material and air voids.
- Optimal design of asphalt mixes from the healing capacity and durability point of view.
- Ensure the recyclability of the HEALROAD mixes by defining the amount of virgin material needed to restore the asphalt mixture properties, including its healing capacity.
- Scaling up the production of HEALROAD mixes in a real asphalt plant.
- Demonstration of the solution proposed:
- Demonstrating the healing capacity of a real scale test section through Accelerated Loading Test.
- Economic and environmental feasibility through a LCA and LCC analysis
The consortium aims to develop a technique which ensures the best value for money and resource efficiency from a road asset management perspective, as well as improving traffic management by reducing the number of roads closed for maintenance.
Although significant advancements in self-healing have already been achieved individually by HEALROAD partners, several issues and uncertainties have been identified during the technical and market deployment of the technique. In this sense, the new consortium brings together a team able to overcome current implementation problems combining experience and knowledge from different backgrounds.
- Description of factors in the chemical composition and the rheology of the bitumen that affect the healing properties the most.
- Assessment of the influence of the air voids content and the type, size and amount of electrically conductive materials in the healing and the mechanical properties of the mixture.
- Two asphalt mixes (PA and AC) with optimal healing capacity and durability.
- Quantification of unknown parameters related to the self-healing of the asphalt mixes
- Maximum lifetime extension of the asphalt mixture.
- Effect of aging on the healing capacity of the asphalt mixes.
- Identification of the optimum time for healing in the lifetime of the road.
- Up-scaling of the production process of the mixes.
- Technical, economic and environmental validation of the technology
The new HEALROAD process will be validated at laboratory scale to verify the reduction of the environmental impact and economic costs by using LCA and LCC techniques. Technical barriers for the future industrialisation and market uptake of healable asphalt mixes via induction heating will be removed by promoting a technology made in Europe and developed by European partners.