Next-gen smart road surfaces prove potential

Self-sensing asphalt being developed at Liverpool John Moores University has the potential to revolutionise the upkeep of Britain’s highways.

The technology which uses electronics to identify voids in the surface of roads and pavements could prove far more robust than current methods which use sensors to alert engineers to crumbling highways.

In 2020-21, the UK government spent £1.5 billion on road maintenance and damage repair.

Dr Yangming Gao, senior lecturer in transport infrastructure in the School of Civil Engineering and Built Environment, said: “The developed self-sensing asphalt can real-time sense its own early-age damage without the need for embedded sensors. Thus, asphalt pavements and roads can be timely maintained and repaired at a low economic cost, reducing road closures and traffic delays.”

Asphalt – a mix of bitumen and mineral aggregates - is used to pave and maintain 95% of UK roads and, if properly maintained, can last up to 25 years.

Local authorities frequently use sensors embedded in asphalt pavement to alert them to deterioration but these have a low survival rate due to traffic loads and climatic conditions. The use of embedded sensors is also causing a high risk of road premature failure.

So how does the new system work?

Self-sensing asphalt contains conductive additives which form a network inside the material. This acts rather like the human nervous system and allows for the instant and real-time detection of problems.

When the material is subject to external traffic loads and damage, its electrical properties change as the conductive network is disturbed. By measuring these changes we can evaluate decomposition of the surface.

An asphalt pavement typically contains around 3-8% air voids, so if a much higher rate is detected, it shows that internal holes have appeared, often invisible to the naked eye.

The material is connected to an electronic circuit and a data acquisition system at the verge of roadways. The electrical data (e.g., electrical resistivity) of the pavements are continuously collected and transmitted to a remote data centre or digital twin platform of roads in real-time, where the electrical responses are evaluated.

Electrical and mechanical tests of the self-sensing asphalt have been done in the lab and described in a paper “Electrical characteristics and conductivity mechanism of self-sensing asphalt concrete” published in the international journal of Construction and Building Materials.

Dr Gao added: “The study has well explored the fundamental aspects of the self-sensing asphalt, including the compositions, the fabrication procedures, and laboratory-scale assessments of the electrical and mechanical properties, but further studies such as the damage-sensing relationships of the self-sensing asphalt and full-scale tests on a real road are needed.”

The university is currently seeking a collaboration with a local authority or constructor to further the research.

The research was conducted in collaboration Professor Patryk Kot, and with colleagues at the Wuhan Institute of Technology, China.