UA professor developing concrete alternative fly-ash

Adrienne Burch

The new buildings and construction sites across the University of Alabama campus will have plenty of positive impact, but the negative effects the construction has on the environment are often ignored.

Concrete is used in almost every construction project across the country, as it accounts for nearly 70 percent of all construction materials. It is so common and widely-used that most people are unaware of the negative effects it can have on the environment.

Jialai Wang, UA associate professor of civil, construction and environmental engineering, is developing an alternative to using cement in the production of concrete. He is working to replace cement with the more eco-friendly material, fly-ash. Fly-ash is a waste material produced from burning coal that can be used to create a stronger, more durable and eco-friendly concrete.

The primary problem with the use of cement is that it releases an abundant amount of carbon dioxide into the atmosphere.

“For every one ton of cement produced, one to one-and-a-half tons of carbon dioxide are released,” Wang said. “The production of cement in the United States accounts for nearly seven percent of the nation’s total carbon dioxide emissions.”

Wang also said that in some developing countries, these numbers could be even higher, with up to 10 percent of all emissions coming from cement production.

Two years ago, Wang received a grant from the National Science Foundation to start his fly-ash research. He has collaborated with engineering professors at Auburn University to use the grant to continue to develop his ideas related to fly-ash.

Fly-ash is currently stored in landfills across the nation, where it can hold traces of toxic elements and cause harm to the environment. This new way of recycling fly-ash into concrete would eliminate the possible toxic burden it places on landfills when stored there.

Several advantages of fly-ash are that it is a natural waste product, so it is easily recycled and is not a burden to landfills. It is also more durable than cement, so roads will last longer and require less upkeep.

As his research has progressed, Wang discovered that fly-ash can become brittle under tension. So, he has experimented with adding carbon nanotubes to the fly-ash, using what he has coined to be the “Poptube” method.

“I call it the Poptube method because using this method is the same as making popcorn in the microwave,” Wang said.

This “Poptube” method uses the radiation from microwaves to cause nanotubes to form in the fly-ash and pop out like popcorn would. Carbon nanotubes are cylindrical carbon structures that, when added to fly-ash, make it stronger and able to conduct electricity. This electrical conductivity is helpful in that it increases the melting of ice on surfaces such as bridges and airplane runways.

“The Poptube method is not only very effective, but more cost-effective and energy-efficient,” Wang said.

Wang has recently received a patent for his Poptube technology. He hopes to continue his research and work toward replacing cement with fly-ash in the production of concrete in the future.