Nebraska bridge heats itself from inside to melt snow during storms

The Roca Spur Bridge in Nebraska, US, has been employing a unique type of concrete to combat snow and ice accumulation for over a decade. Rather than solely depending on salt, chemicals, or snow-clearing vehicles, this 150-foot bridge can generate heat within its own structure by transmitting an electrical current through conductive concrete slabs.

Developed by Chris Tuan, a civil engineering professor at the University of Nebraska-Lincoln (UNL), alongside the Nebraska Department of Roads, the system was first implemented in 2002. The bridge features 52 conductive concrete slabs embedded in its surface. The innovative concrete mixture incorporates steel shavings and carbon particles, enabling the material to conduct electricity and produce heat sufficient to melt snow and ice from its surface.

During a winter storm in Omaha in December 2015, a 200-square-foot slab outside UNL's Peter Kiewit Institute initially accumulated snow like the surrounding ground. However, as time progressed, the snow gradually melted from the slab's surface as the concrete produced enough heat while remaining safe to touch. This conductive concrete system functions by primarily using standard concrete, with around 20% of the mixture consisting of additional conductive materials, such as steel shavings and carbon particles.

When an electrical current flows through the conductive concrete, it heats up, which is then utilized to melt snow and ice on the surface. While Tuan's team has explored various applications for this technology, they emphasize that replacing all traditional road surfaces with conductive concrete would not be cost-effective. Instead, the system could be strategically employed at locations prone to repeated ice formation, such as bridges, which are particularly susceptible to freezing due to their exposure to elements from both above and below.

One of the main advantages of this conductive concrete is its potential to reduce the reliance on traditional de-icing methods, which often involve the excessive use of salt and chemicals that can lead to concrete corrosion and groundwater contamination. The electrical system powering the Roca Spur Bridge's de-icing function during a typical three-day storm costs approximately $250, which is significantly less expensive than purchasing and deploying large quantities of de-icing chemicals.

Additionally, the technology has been tested for use at airports, where the FAA sought to clear the tarmac areas around gates where numerous service vehicles need to operate. Tuan's research team discovered that replacing certain materials, such as limestone and sand, with magnetite, a mineral, could grant the concrete the ability to shield against electromagnetic waves.

This finding has potential applications beyond winter road safety, although de-icing remains the primary focus of the technology's development. Tuan has even incorporated conductive concrete into his personal property, using it for a patio in his backyard, demonstrating his commitment to the technology.