If you were to walk through downtown Greenville, you would likely notice several landmarks, including the Liberty Bridge and the old county courthouse.
While these iconic structures are unique in their own right, they share one commonality: They’re made of concrete. The coarse, gray material is the very foundation of modern infrastructure. It’s been used in the construction of everything from buildings and bridges to roads and sidewalks.
But despite all its benefits of strength and durability, there’s a major downside to using concrete.
The production of cement, which when mixed with water forms the binding agent in concrete, accounts for 5 to 10 percent of all human-caused carbon dioxide emissions, according to the International Energy Agency. These emissions have been on the rise since the industrial revolution and remain the leading cause of global warming.
Over the past decade, though, researchers from across the country have been working together to create a cleaner version of the versatile building material. And now they plan to test the capabilities of their environmentally friendly alternative in Greenville.
The U.S. Endowment for Forestry and Communities, a Greenville-based environmental nonprofit, has partnered with the U.S. Forest Service, Oregon State University, and Purdue University to study a concrete mixture infused with cellulosic nanomaterials.
Cellulosic nanomaterials are produced by breaking down wood to its smallest, strongest components through mechanical and chemical processes similar to making paper. These tiny rodlike structures have diameters 20,000 times smaller than the width of a human hair and can be seen only using an electron microscope, yet they are as strong as steel with only one-fifth the weight.
“Researchers are testing these cellulosic nanomaterials in a wide range of applications from substrate for computer chips, they don’t warp under heat like plastics do, to car and airplane bodies, lighter and stronger than steel,” said Dr. Alan Rudie, a chemist with the U.S. Forest Service’s Forest Products Laboratory in Wisconsin, in a news release. “Our team expects that concrete will be among the first commercial applications.”
While traditional concrete remains one of the most widely used construction materials in the world, its strength and durability are hampered by the fact that not all of the cement particles are hydrated after being mixed.
The addition of cellulosic nanomaterials, however, increases the hydration of cement particles, thus making it stronger, according to Dr. Jason Weiss, a professor of civil and construction engineering at Oregon State University. In lab tests, the addition of the nanomaterials increased the tensile strength of traditional concrete by 15 percent, improving it enough to help prevent cracks.
The U.S. Endowment for Forestry and Communities, along with its research partners, plans to conduct a head-to-head comparison of nanomaterial-enhanced concrete with traditional concrete by reconstructing its 25-by-45-foot parking lot on East North Street and pouring 32 tons of each mixture at the site. The nonprofit will be working with Harper General Contractors, SynTerra Corp., and Thomas Concrete to rebuild the parking lot starting this month.
Carlton Owen, president and CEO of the U.S. Endowment for Forestry and Communities, said the long-term goal of the study is to test how well the nanomaterial-enhanced mixture compares with traditional concrete when it comes to reducing carbon emissions, materials used, and cost. The nonprofit’s parking lot is one of three test sites nationwide.
“We are excited to be spotlighting Greenville in this project,” Owen said. “This test aims to show what the future of sustainability can be.”
Manufacturing cement produces large amounts of carbon dioxide emissions because it involves burning fuel to heat a powdered mixture of limestone and clay at temperatures exceeding 2,000 degrees Fahrenheit. When cement is mixed with water, a paste is formed. Sand and gravel are then added to the paste to make concrete.
By adding cellulosic nanomaterials to the mixture, concrete structures become more resistant to corrosion and last longer. This enables the construction industry to use less cement, resulting in a reduction in carbon dioxide emissions.
The addition of cellulosic nanomaterials to concrete could also improve the sustainability of forest management efforts by providing a market for low-value wood, according to Rudie. Public-land managers typically remove this type of wood from forests to reduce the risks of catastrophic wildfire and other threats but can’t find uses for it.
“Removing low value wood is expensive, so finding markets is critical to forest health and sustainability,” Rudie said. “Products made with CN [cellulosic nanomaterials] could provide one of the most important answers to keeping our forests as forests and ensuring their health and sustainability.”
A group of scientists from Purdue University and Oregon State University began looking into the uses of cellulosic nanomaterials a decade ago in collaboration with Robert Moon, a materials research engineer at the U.S. Forest Service’s Forest Products Laboratory.
Their work, which was funded by the National Science Foundation, has since inspired similar research across the world, including a $480,000 project at Clemson University that aims to use cellulosic nanomaterials to develop composite materials that could be shaped into automotive parts with improved strength. In fact, the International Organization for Standardization published a set of global standards and definitions last year for the industrial production of cellulosic nanomaterials.
Rick Richardson, vice president at Harper General Contractors, said his company is working with the U.S. Endowment for Forestry and Communities to establish a local testing site for cellulosic nanomaterials because of its long-ranging applications.
“We are a company that values cutting-edge ideas along with creating a more sustainable future,” he said. “This project allows us to do both while working in a city and community that has been our home for generations.”
SynTerra Corp., a Greenville-based regional provider of environmental consulting services to industrial and governmental clients, will provide engineering throughout the project.
“We’re always looking for creative solutions, and we’re always mindful about the environment,” said Mike Hutchinson, a senior civil engineer at SynTerra. “Working with this technology puts a checkmark in both boxes.”
For more information, visit www.fs.fed.us.