Innovative self-heating concrete technology was developed by scientists from Drexel University in Pennsylvania. They integrated a phase-changing material into the concrete – paraffin, which is capable of absorbing and releasing thermal energy when its physical state changes.

The goal of the development was to create an alternative to traditional methods of de-icing roads, such as spreading salt, which damages the road surface. The results were published in the Journal of Materials in Civil Engineering.

Paraffin wax encapsulated in concrete begins to crystallize as the ambient temperature drops, releasing heat. This helps maintain the surface temperature of the concrete above zero degrees, preventing ice formation and snow accumulation. The researchers tried two methods of introducing wax into the concrete mixture: dipping the aggregates in liquid wax before mixing and adding wax capsules directly into the mixture.

In tests conducted since 2021, phase-shifting concrete slabs have demonstrated the ability to maintain surface temperatures ranging from 5.6 to 12.8°C for 10 hours at sub-zero temperatures. They successfully melted a layer of snow up to 5 cm thick at a rate of about 6.35 mm per hour. Concrete with aggregates immersed in paraffin showed the greatest efficiency.

Despite the promise of the technology, scientists noted some limitations. Phase-shifting concrete had difficulty melting snow cover more than 5 cm thick. In addition, to work effectively, paraffin must “recharge” between freezing and thawing cycles, absorbing a sufficient amount of heat.

The researchers emphasize the importance of using environmentally friendly and renewable sources of wax, such as synthetic or biodegradable types, if the technology is to be implemented at scale.