Philadelphia is bracing for dropping temperatures and the potential for snowfall, leading residents to navigate layers of road salt used to prevent ice and snow from accumulating on sidewalks and streets. However, a groundbreaking initiative at Drexel University aims to change this approach by developing self-heating concrete that can autonomously melt ice, thereby addressing both safety and environmental concerns associated with traditional salting methods.
According to Amir Farnam, an associate engineering professor and head of Drexel’s Advanced Infrastructure Materials Lab, the use of road salt can be labor-intensive, damage infrastructure, and pollute the surrounding soil. “We wanted to create an alternative solution,” he stated.
Farnam’s team has engineered two types of concrete that incorporate paraffin wax—a petroleum byproduct commonly found in candles and crayons. These innovative materials were tested in a university courtyard, where they were subjected to natural weather conditions. Remarkably, both concrete variants effectively melted snow under varying climatic circumstances, as evidenced by video recordings captured during a February 2022 snowstorm. While standard concrete was buried beneath snow, the self-heating slabs remained clear for extended periods.
The self-heating capability stems from the unique characteristics of phase-change materials. When exposed to warmth and sunlight, paraffin wax liquefies; conversely, in colder temperatures, it solidifies, releasing heat in the process. Farnam likened this to battery mechanics, explaining, “Paraffins recharge when there’s sun and heat, turning into their liquid phase. When snow or rain or a cold event comes, they start solidifying and releasing heat.”
The research team employed two distinct methods to incorporate paraffin into the concrete. One method involved encapsulating paraffin and mixing those capsules into the concrete, which allowed for rapid snow melting but had a limited temperature range. The second method infused pebbles with paraffin before mixing them with standard concrete, resulting in longer-lasting heat release, making it suitable for a broader temperature spectrum. This variant could help detach ice from road surfaces for easier plowing.
Despite these advancements, Farnam cautioned that Philadelphia should not entirely abandon its snowplows and salting crews. In prolonged cold spells, for instance, the paraffin might release heat as temperatures drop and remain solid until they rise again. “If you’re designing for Philly, it’s not going to be working 100% of the time,” he noted.
Nevertheless, during snowy conditions in Philadelphia from 2021 to 2024, the self-heating concrete proved effective over 50% of the time, with the temperature falling below freezing on 32 occasions and more than an inch of snow recorded five times, according to Drexel’s reports.
Moreover, Farnam highlighted the durability of self-heating concrete against the freeze-thaw cycles that contribute to pothole formation and road degradation. He suggested that a blend of traditional salt and this innovative technology could significantly reduce salt use. “Even a 50% reduction in salt use over the lifespan of a road—10 to 15 years—is substantial. It saves costs, energy, and extends service life,” he asserted. A road that typically lasts a decade could potentially last two decades with this technology.
The future adoption of self-heating concrete by municipalities or developers remains uncertain. Farnam, who has a patent pending for the developed concrete, noted interest from a company eager to market the innovation. He also recalled a decade-old inquiry from the Federal Aviation Administration about enhancing runway de-icing methods.
However, initial costs pose a challenge, as the price of self-heating concrete could be two to three times higher than traditional alternatives. “It would be really hard to convince a Department of Transportation to implement it,” Farnam acknowledged. Ultimately, he believes that the long-term savings in maintenance and road replacements could lead to significant taxpayer savings. “You could save a lot of taxpayers’ money,” he concluded.
