According to the American Road and Transportation Builders Association, a staggering one in three bridges in the U.S. requires repair or replacement. This equates to over 200,000 bridges nationwide. A primary factor contributing to this aging infrastructure issue is the corrosion of rebar, which weakens and cracks the concrete around it, ultimately increasing the risk of catastrophic bridge failures.
Enter Allium Engineering, a company launched by two innovative MIT PhD graduates. Their groundbreaking technology extends the lifespan of bridges and structures by using stainless steel cladding to protect rebar from corrosion. By stopping corrosion in its tracks, infrastructure not only lasts significantly longer but also requires fewer repairs, thereby reducing carbon emissions. This advanced method easily integrates into existing steel-making processes, making America’s infrastructure not just longer-lasting but also more affordable and environmentally sustainable going forward.
“In the U.S., a typical bridge deck has a lifespan of around 30 years; we’re aiming for 100 years,” remarks Allium co-founder and CEO Steven Jepeal, PhD ’21. “A vast amount of our infrastructure is overdue for replacement, primarily because the materials used haven’t met the demands.” Jepeal underscores the need for a sustainable approach as the nation seeks to revitalize its infrastructure.
To achieve their goals, Allium layers a thin protective coat of stainless steel over standard steel rebar, dramatically enhancing its corrosion resistance. So far, about 100,000 pounds of Allium’s stainless steel-clad rebar have been utilized in various construction projects across the United States, and the company believes its production method can be rapidly scaled alongside steel mills.
“We seamlessly integrate our technology into existing mills, enabling them to produce more durable materials without altering their processes,” Jepeal explains. “This transformation is essential for all infrastructure to become more resilient.”
Strengthening Bridges
Jepeal completed his PhD in the MIT Department of Nuclear Science and Engineering (NSE) with Professor Zach Hartwig. His experience witnessing the creation of Commonwealth Fusion Systems fueled his entrepreneurial spirit. “It definitely ignited my interest in startups,” he reflects. “MIT equipped me with essential materials science knowledge.”
Meanwhile, McAlpine earned his PhD under Associate Professor Michael Short. In 2019, they collaborated on an ARPA-E-funded project that sought to enhance corrosion resistance in metals. The duo realized their technology could serve everyday applications and began engaging with MIT’s Venture Mentoring Service and industry leaders like Tata Steel, a top global steel manufacturer that had identified corrosion as a significant concern.
One of their initial challenges was to apply corrosion-resistant materials economically without disrupting traditional production lines. Steelmaking starts with massive precursor steel pieces that are rolled at extremely high temperatures, almost like making industrial-scale pasta. They devised a solution: add their cladding before this rolling process. While customized, their system leverages tools already in use in other metal processing tasks, such as welding, to apply the cladding effectively.
“We embed stainless steel on the surface of cost-effective carbon steel, usually recycled scrap from products like cars and refrigerators,” Jepeal explains. The result? Each 40-foot piece of precursor steel transforms into roughly a mile of durable rebar. In the end, rebar processed by Allium maintains over 95% of its original carbon steel composition, requiring no special post-processing or handling.
“What emerges from the mills appears and performs like regular rebar,” says Jepeal. “It’s just as strong and can be manipulated just like any normal rebar. However, instead of a 30-year lifespan, it has the potential to last over 100 years.”
Building for the Future
Last year, Allium launched its first commercial cladding operations in Billerica, Massachusetts, producing around 100 tons of stainless steel-clad rebar in collaboration with a partner steel mill. This robust rebar is already being utilized in construction across California and Florida.
The company’s initial facility has a production capacity of about 1,000 tons of long-lasting rebar annually, but they aspire to open more facilities closer to their partnering mills, ultimately embedding them within mill operations.
“We are driven by our mission to reduce emissions and enhance infrastructure, which propels us to scale rapidly to meet industry needs,” Jepeal states. “Every conversation we have indicates a demand for expanded production.”
Allium also explores other cladding materials and composites. Looking ahead, Jepeal envisions their technology extending beyond rebar to include applications like train tracks, steel beams, and pipes. Nevertheless, he emphasizes that the primary focus remains on rebar for the foreseeable future.
“Corrosion affects nearly all of our infrastructure, making it the biggest issue we aim to tackle with our expertise,” Jepeal concludes. “From tunnels and bridges to roads and power plants, this is a pervasive problem.”
Photo credit & article inspired by: Massachusetts Institute of Technology
