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Montana Tech Students Seek to Develop 'Green Concrete'

For their senior design project, civil engineering students at Montana Technological University are combining concrete with waste products in an effort to develop a mixture that would reduce concrete's carbon footprint.

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Credit: Montana Technological University Facebook page
(TNS) — The fun followed the grit and grind of completing each step of the scientific method.

The five empiricists, all seniors at Montana Technological University, said they enjoyed testing the strength of the cylinders they'd formed from unique mixes of concrete.

The compression testing involved subjecting each cylinder to increasing pressure until it fractured.

The goal of the full-year Senior Design Project was to lessen the carbon footprint of concrete production, which is a significant contributor of carbon dioxide.

The students tested the performance of concrete with waste products in the mix instead of a full complement of cement in a quest for "green concrete."

Conventional concrete is a mix of cement, gravel, sand, water and a range of aggregates, a term that can refer to crushed stone, gravel, sand or other construction materials.

The interdisciplinary team at Montana Tech included civil engineering students Colton Grange of Philipsburg, Connor Johnson of Whitehall and Gabriel Sims of Billings. In addition, environmental engineering students Nevada Strandberg of Helena and Shyla Wesely of Glasgow brought expertise from their discipline.

The students acknowledged it took a while for the varied disciplines to mesh but that teamwork prevailed.

"I would say the greatest challenge was learning how to work as a team with people from a different engineering department and coordinating final decisions that work for everyone," Johnson said.

They tested a few different waste products: tailings from Montana Resources' Yankee Doodle Tailings Pond, slag from the former smelter in Anaconda, sludge from the wastewater treatment plant and biochar (black carbon produced from biomass sources such as wood chips, manure and other agricultural waste products).

In the end, the concrete mix with tailings replacing a percentage of cement consistently demonstrated the greatest strength, the students said.

According to numerous sources, including industry associations, the production of cement and concrete yields a substantial carbon footprint.

Among other contributors to that footprint, cement is made by firing limestone, clay and other materials in a kiln. Carbon dioxide is emitted from the energy used to fire the material and the chemical reaction produced from the mixture when it is exposed to heat, according to Princeton University.

The National Ready Mixed Concrete Association says each pound of concrete releases about 0.93 pounds of CO2.

The Pennsylvania Aggregates and Concrete Association defines green concrete as "a form of eco-friendly concrete that is manufactured using waste and residual materials from different industries and requires less energy for production."

The Pennsylvania association adds, "The aim of using green concrete is to lessen the burden on natural resources and increase dependency on recyclable materials."

In addition to greenhouse gases, concrete plant emissions typically include mercury, particulate matter and more. Concrete plants' industrial footprint also includes deep and sprawling quarries tied to mining of raw materials.

Titan America LLC, headquartered in Norfolk, Virginia, is one of many concrete producers that has described intentions to lower its carbon footprint. The Titan Cement Group has committed to deliver net zero concrete by 2050.

Expert Market Research, with offices in Sheridan, Wyoming, and New Delhi, India, forecast a bright future for green concrete, with higher demand in Europe and Asia Pacific. According to the company, "The global concrete market reached a value of $6.3 billion in 2022" and is expected to reach a value of about $11.5 billion by 2028.

The Montana Tech concrete team said they've been contacted to date by two companies wanting to learn more about their project.

Robin Bullock, associate professor of environmental engineering, said Montana Tech's Senior Design Course "provides students the opportunity to choose a real-world problem, work with other disciplines and get their hands into the build."

"This project has been excellent for the personal and professional growth of all of us," Grange said.

©2023 The Montana Standard (Butte, Mont.). Distributed by Tribune Content Agency, LLC.