How is one university transportation engineering student with a knack for science trying to save the environment? And why are states like Texas reimagining the way we create highways and bridges? This story is about infrastructure. It’s a hot topic in transportation today—but it’ll become even more important in years to come.
Transportation infrastructure includes highways, airport runways, bridges, waterways, and city streets—or, basically anything we travel on instead of in. Nations rely on transportation infrastructure in a huge way: imagine a world without roads, bridges, or airports.
To build infrastructure you need resources like workers, materials, and taxpayer dollars. But it doesn’t stop there. A country has to maintain its infrastructure, too. Otherwise, as the decades roll by, you end up with expensive land waste: collapsed bridges, cracked highways, and crumbling runways. Relics of something once great, now deteriorated to uselessness.
If infrastructure is the plot of this story, the main character is concrete.
It is no understatement to say that we have built our society on concrete. It paves our highways; supports our bridges; lets us construct buildings that tower into the sky. You might say concrete is the main ingredient in infrastructure.
Concrete is made of three main ingredients: rock, water, and cement. And you might say that cement is the key to this story. It’s what keeps transportation research students like Trevor Williamson up late working in the lab. It’s also why states are spending money and manpower in search of scientific answers to an environmental concern.
Cement is like the glue that holds concrete together. Without cement, you can’t have infrastructure. To make cement, workers quarry for limestone and clay. They haul the quarried stone to a factory, where it’s crushed into smaller and smaller bits, until it’s about the size of a golf ball. Then it goes to the kiln.
The limestone and other ingredients (such as minerals) are heated in the kiln to temperatures up to 2,700 degrees Fahrenheit. At these temperatures, the mixture becomes molten, almost like lava. This causes chemical reactions to take place. Then, workers allow it to cool.
What comes out of the kiln is marble-sized chunks of cement-ready material called clinker. When the clinker is ground into a fine powder and mixed with water, magic happens. It transforms into cement.
But there is a villain in this story. Heat.
When the limestone mixture is heated in the kiln, the heat causes a massive release of carbon dioxide (CO2), which enters our atmosphere and is the main contributor to global warming. We’re used to hearing about emissions from our cars and power plants contributing to the greenhouse effect. But when you think about how much concrete it takes to build and maintain America’s infrastructure, suddenly it’s not so hard to believe that concrete production accounts for up to 10% of global CO2 emissions.
In order to reduce our concrete-related CO2 emissions, what are our options? Stop building things?
Enter transportation researchers like Trevor Williamson, who are searching for ways to eliminate most of the greenhouse gas from the cement manufacturing process.
At the University of Texas at Austin, working with his adviser Dr. Maria Juenger, Trevor is experimenting with a new type of cement that would release 60% less CO2 during the manufacturing process. The material, called geopolymers, can be produced at much, much lower temperatures than regular cement because the substance it’s made of requires chemical reactions instead of heat. And amazingly, the substance inside geopolymers, called fly ash, is made of coal residue produced by coal-burning power plants. This means that, by using fly ash, which would otherwise be dumped into a landfill, geopolymers turn a material that would normally pollute the environment into one that could help save it.
Fly ash is already being used for construction purposes in states like Texas, who want to play their part in reversing global warming. The Texas Department of Transportation has even been funding research on the possibility of using fly ash that’s been reclaimed from landfills. By replacing a percentage of limestone with fly ash, manufacturers could eliminate some of the limestone quarrying traditionally needed to make cement.
Using fly ash can also make cement more durable resulting in less quarrying and less CO2 emissions. And, if concrete is more durable, then the infrastructure is more durable, requiring less repairing and rebuilding. This results in less cement needing to be produced.
Check out Trevor’s video to learn more about his environment-saving research. Then, do your own research to find out the many ways states like Texas are trying to change transportation’s environmental impact. Who knows? Maybe you’ll be the next hero in the story of infrastructure.