PHILADELPHIA — Could roadways of the future melt wintry precipitation on their own and make salt trucks a thing of the past? Researchers have discovered that adding a simple ingredient to concrete gives it a powerful ability to melt snow.
The new paving surface, developed by Drexel University researchers, has the potential to keep millions of tons of salt and deicing chemicals out of the environment. Using only a small amount of paraffin wax as the secret ingredient, the snow melting concrete utilizes the energy released by the wax’s special “phase change” properties.
“Phase change materials can be incorporated into concrete using porous lightweight aggregate or embedded pipes and when PCM transforms from liquid to solid during cooling events, it can release thermal heat that can be used to melt ice and snow,” says assistant professor of civil engineering Yaghoob Farnam in a press release.
“By inhibiting the formation of ice and snow on the pavement or bridge surface, the use of PCM may reduce or eliminate the need for deicing chemicals/salts, snowplowing or both — thus saving money and positively influencing the environmental impact of such operations,” he adds.
Farnam, who led the research team that included scientists from Purdue University and Oregon State University, says this is the first time it has been shown a phase change material can be as effective as salting and scraping.
A common and relatively inexpensive ingredient, paraffin wax was tested in both tubes embedded in concrete and as an ingredient simply mixed into the material. While paraffin in tubes melted snow faster when air temperature was above freezing, the researchers found the concrete with paraffin mixed directly in worked better when air temperatures were already below freezing before the simulated snowfall.
“The gradual heat release due to the different pore sizes in porous light-weight aggregate is more beneficial in melting snow when concrete is exposed to variety of temperature changes when snow melting or deicing is needed,” Farnam says. “We believe that using porous lightweight aggregate can be potential way of incorporating phase change materials in concrete as it is easy to be implemented in practice and can cover environmental conditions of various locations in the US dealing with snow, especially melting snow or deicing in roads and bridges in the Northeast.”
The researchers are also looking at the possibility of using the material at airports, though the process for approval of a new material can be arduous.
“A new concrete formulation needs very, very thorough field testing before contractors would dare to use it, because there are liability issues,” says Deborah Chung, an engineering professor at University at Buffalo, in a National Geographic article. “To get a new concrete to be accepted by contractors, it’s a long haul.”
Then addressing another snow melting concrete that relies on an electrical current, Chung said the advantage of such a conductive concrete would be its ability to also be used to shield against lightning strikes or block cell phone communications.
While such extra benefits of conductive concrete are interesting, researchers and civil engineers are no doubt interested in the ability for the paraffin wax alternatives to work without outside input.
In the case of the conductive concrete Chung spoke of, researchers said one of the roadblocks to progress was that such systems need to be turned on and off. In the case of the wax concrete, it just works by itself.
The findings on the new material were recently published in the journal Cement and Concrete Composites.