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A Massachusetts startup claims its stainless-steel-bonded rebar can extend bridge deck service life to 100 years or more – and the reinforcements are already being used in California.
Allium Engineering, founded by MIT alumni Steven Jepeal and Sam McAlpine, developed the stainless-steel-clad rebar to be resilient to corrosion.
Rusty rebar can crack the concrete around it, making bridges more susceptible to collapsing. Eliminating the possibility of corrosion means reducing the number of repairs and extending the life of critical infrastructure such as bridges.
“Across the U.S., the typical bridge deck lasts about 30 years on average — we’re enabling 100-year lifetimes,” Jepeal told MIT News. “There’s a huge backlog of infrastructure that needs to be replaced, and that has frankly aged faster than it was expected to, largely because the materials we were using at the time weren’t cut out for the job. We’re trying to ride the momentum of rebuilding America’s infrastructure, but rebuild in a way that makes it last.”
Allium’s process involves adding a thin, protective layer (less than 1-mm-thick) of Type 316 stainless steel on top of traditional ASTM A615/A706 carbon-steel rebar to make it more resistant to corrosion. The resulting mix has no gaps, breaks, or hard barriers between the two materials.
The innovation has already seen significant use, with roughly 100,000 lbs. of the rebar installed as part of construction projects around the U.S.
“We integrate our system into mills so they don’t have to do anything differently,” Jepeal explained. “We add everything we need to make a normal product into a stainless-clad product so that any mill out there can make a material that won’t corrode. That’s what needs to happen for all of the world’s infrastructure to be longer lasting.”
According to a recent Engineering News-Record article, Caltrans installed about 70,000 lbs. of the reinforced rebar on the Long Valley Creek Bridge deck along U.S. 101 in Mendocino County in the spring of 2025. The project – which marked the first use of stainless-bonded rebar on a California bridge – wrapped in April, and the California Department of Transportation continues to evaluate the rebar as it does with all new materials.
“Allium exceeded expectations,” said Gregg Granillo, vice president of fabricator ALTA Rebar, who provided a testimonial about using the product. “…our ironworkers found it familiar and easy to use.”
Allium shared a lifecycle analysis for the Caltrans deck with ENR, which is based on publicly available data from Caltrans and the Federal Highway Administration. The analysis stated a projected 87% reduction in deck ownership cost over 75 years due to savings such as less maintenance cost to replace deck rebar that’s worn down by traffic.
Caltrans has yet to release its project evaluation data, and Allium’s numbers have not undergone independent review.
“We designed it to behave exactly like conventional rebar in the field – same bends, same specs – so engineers aren’t relearning the basics,” McAlpine told ENR. “They’re just gaining corrosion resistance.”
The State of America’s Bridges
There are more than 623,000 bridges across the United States, according to the American Society of Civil Engineers (ASCE) 2025 Report Card for America’s Infrastructure.
The ASCE gave America’s bridges a C in that report card, citing the fact that 49.1% of the country’s bridges are in “fair” condition, 44.1% are in “good” condition, and 6.8% are in “poor” condition.
“Unfortunately, the nation continues to see the number of fair bridges surpassing those in good condition,” the ASCE wrote. “As bridges in fair condition continue to age – presenting the possibility of being further downgraded – they also exemplify an opportunity because they can be preserved at a lower cost than bridges in poor condition.”
Bridges received a significant amount of funding through the Infrastructure Investment and Jobs Act (IIJA), which included $27.5 billion for the Bridge Formula Program and $12.5 billion for the Bridge Investment Program.
“Despite this infusion of federal funding, bridge-related system rehabilitation needs are estimated at $191 billion,” the ASCE wrote. “Therefore, strategic asset management planning and routine maintenance are essential to keeping bridge conditions from further declining and avoiding costly repair or rehabilitation work. While the effects of extreme weather events pose threats to bridges, innovative techniques are improving their security and resilience.”
Whether or not innovations like Allium’s stainless steel-clad rebar truly revolutionize bridge construction and maintenance, it’s important that you know exactly where all reinforcements are within bridge decks and other concrete slabs before you attempt to cut or core that concrete.
Striking rebar, post tension cables or other support systems within concrete can lead to catastrophic structural failure that endangers you and your workers, and anyone else in the vicinity of your job site.
GPRS provides precision concrete scanning and imaging services designed to keep your concrete cutting and coring projects on time, on budget, and safe. Utilizing state-of-the-art ground penetrating radar (GPR) scanners and other, complementary technologies, we visualize where you can and can’t safely penetrate the slab, providing you with accurate, actionable information that helps you plan, build, and manage better.
Our SIM-certified Project Managers have achieved and maintain a 99.8%+ rate of accuracy when scanning concrete slabs for buried rebar, post tension cable, electrical conduit, and any other types of embedded obstructions that could compromise the safety and success of your project. We’re so confident in their abilities that we introduced the Green Box Guarantee, which states that when we place a Green Box within a concrete layout prior to you cutting or coring that slab, we guarantee that the area within will be free of any obstructions.
If we’re wrong, we agree to pay the cost of the damage.
From bridges to skyscrapers, GPRS Intelligently Visualizes The Built World® to keep your projects on time, on budget, and safe.
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Frequently Asked Questions
How is GPR used to identify tendons vs. rebar in a post-tensioned slab?
In post-tensioned structures, we typically find one mat of support rebar near the base of the slab. This mat is generally consistently spaced and remains at a constant elevation.
Post-tension cables are generally found above this support mat and “draped” throughout the rest of the structure. The elevation of the cable is usually high near the beams and column lines and drapes lower through the span between beams and column lines. Knowledge of these structural differences allows us to accurately differentiate between components. Our Project Managers will leave you feeling confident in our findings and in your ability to drill or cut without issue.
What types of concrete scanning does GPRS provide?
GPRS provides two specific but different scanning services: elevated concrete slab scanning and concrete slab-on-grade locating. Elevated concrete slab scanning involves detecting embedded electrical conduits, rebar, post-tension cables, and more before core drilling a hole through the slab. Performing a concrete slab-on-grade locating service typically involves scanning a trench line for conduits before conducting saw cutting and trenching to install a sanitary pipe, water line, or something similar.
