Ohio State researchers seek to put coal combustion products to use

College of Engineering faculty recently joined Brixx Technology LLC and 20 additional interested companies and agencies for a grand showing of a new manufacturing facility in Toronto, Ohio, that will turn waste products from coal burning into new construction materials.

As part of its Coal Combustion Products (CCP) Program, faculty in the Department of Civil, Environmental, and Geodetic Engineering (CEGE) at The Ohio State University are collaborating with Brixx to recycle coal combustion byproducts into concrete and brick products.

“There are countless ways coal ash can be used for construction, agriculture, horticulture, and mine remediation,” Tarunjit Butalia, Director of the CCP Program, noted. “Concrete applications have the highest value on the market.”

The byproducts of burning coal and filtering gas emissions are known as coal combustion residuals (CCRs), which include fly ash, bottom ash, flue gas desulfurization (FGD) solids, and other ashes. Typically, these materials are considered industrial waste and are disposed of in designated landfills and coal ash ponds.

However, CCRs can be beneficially reused in brick and concrete products, structural fills, and material fills such as paints and plastics. In agriculture, CCRs can stabilize soil and limit runoff from pesticides and herbicides. They are also used for waste stabilization, embankment construction, and coal mine reclamation. Ohio State’s CCP Program is working towards remining and remediating landfills, coal ash ponds, and retired coal plants using CCRs.

In 2022, Brixx and CEGE connected at the World of Coal Ash Conference, beginning their collaboration on CCPs. Butalia, an affiliated faculty member of Ohio State’s Sustainability Institute, tested the durability of concrete products, focusing on finding ways to incorporate CCPs into industrial products for beneficial reuse. This includes work with private industries and policymakers, specializing in their use as construction materials and mine remediation. Butalia noted that removing coal ash from retired coal plants helps prevent them from becoming Superfund sites, which can require expensive and long-term environmental remediation.

Initially founded in Houston, Texas, by CEO Randall Stremmel, Brixx Technology uses CCRs and other industrial wastes in its patented cement-free brick, concrete mold, and cinder block products. Stremmel wanted to bring these technologies to Ohio because of its advantageous proximity to CCR supply.

In 2021, the Ohio Environmental Protection Agency (EPA) approved Brixx to manufacture fly ash bricks at its Toronto, Ohio facility and remediate the nearby retired W.H. Sammis plant and Richmond Mill Inc. No. 2 landfill site. Brixx is the first company in Ohio to reuse fly ash in other products.

Brixx started manufacturing by harvesting fly ash from the Richmond Mill disposal site. The fly ash is thermally cured with two binding agents, allowing pressure and heat to form into a mold. This creates a crystal that encapsulates the materials, making it non-leachable and durable. The final products, aggregates, are manufactured into concrete and other materials, replacing virgin ingredients for improved environmental impact and a more circular economy.

Lisa Burris, CEGE Associate Professor, focuses on creating sustainable pervious concrete. Burris is working towards increasing durability, reducing costs, and curtailing carbon emissions from concrete materials.

“Ohio State is funding CCR reuse and reclamation research projects,” Burris said at the Brixx facility showing. “This is just one example of the university’s commitment to developing circular economies that help protect the environment while growing new economic opportunities in Ohio.”

Stremmel said that Brixx plans to speed up production to 80,000 tons of coal ash products annually at the Toronto facility. After adding three shifts, production is expected to increase to 200,000 tons annually.

Brixx uses 70% less energy and emits 80% less CO2 than traditional concrete and brick manufacturing processes. In addition, Brixx’s products are certified by the Leadership in Energy and Environmental Design (LEED) program and can be used to support green infrastructure projects. Brixx also works with regulatory agencies to utilize the products in flood control and climate-resilient infrastructure projects. However, work remains to ensure the projects meet National Pollutant Discharge Elimination System (NPDES) leachate standards.

The strength of the bricks is 8,000-10,000 pounds per square inch (psi), which exceeds the strength requirement for bricks at just 2,000 psi. Recognizing their structural strength, the Ohio Department of Transportation (ODOT) has accepted Brixx’s products for structural bricks and aggregates for concrete.

This work is partly funded by the Coal Development Office of the Ohio Department of Development through two grants to Ohio State. Dr. Butalia is the principal investigator for the beneficial use of harvest CCRs, while Dr. Burris leads the project on using these materials in concrete applications.

“We are thankful for the strong, positive relationships we have built in Ohio with The Ohio State University,” Stremmel said. “Ohio EPA has been an important source of support throughout the establishment of the manufacturing facility. Likewise, the neighboring Toronto, Ohio community members have supported our ability to bring jobs back to the area, particularly following the closure of the area’s coal plant.”

“We look forward to continuing our collaboration with Brixx,” Butalia said. “Ohio State plays a major role in testing its coal ash concrete products to ensure durability, non-leachate compliance, and quality.”

- by Christine Andreeva, Student Communications Assistant, Sustainability Institute