The co-founders Steven Jepeal and Sam Mcalpine, who received a doctorate at the Massachusetts Institute of Technology, describe the product as a conventional ASTM ASTM A615/A706 Rebar-Seteell de Carbon, which has the outside with a layer of about 2 mm of type 316 type 316, approximately 5% in volume, which was surrendered for the rhythm.
“ There is a regular receiving and stainless steel outside and, microstructurally, they are so well linked that there is a region where they are intertwined, which is called “ interdifusion ”, he says Jepeal, adding, “ so what you finish is a piece of steel, it does not hunger, there are no breaks, or a hard neighborhood of the other. ”
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Jepeal described the process of creating the outer layer of stainlessness as similar to converting regular carbon steel into a stainless alloy.
The bar encounters Aashhto M 329m, the only United States specification that defines stainless link reinforcement, according to the company. In Astm Rapid macrocell Tests that simulates high chloride conditions, Allium reports a 20 -time fall in the corrosion current in front of the regular carbon steel bar for 12 weeks. These results have not yet been independently reviewed.
Allium is priced at 20% at 40% above the receipt covered epoxy, about $ 1,600 to $ 1,800 per ton, or 0.90 to $ 1.10 per feet, but below the completely stainless stainless stainless options, which can work from two to three times more and increase the weight of the project considerably.
Analysis of the company’s life cycle for the hotel cover, shared with Enr, projects a reduction of 87% of the cost of ownership of the cover of more than 75 years, until savings, such as a maintenance cost to replace the roof bar that is worn by traffic, using the data of the publicly available hot and federal Highway. As is standard in industry, Allium is based on ASTM/AASHTO compliance and the feedback of owners instead of a specific performance guarantee.
Yellow bars show the initial weight (LB/FT) of the Astm A615 standard bar; Orange overlapping show the additional weight of the 2 mm Allium stainless coating. The two sizes ( #4 and #5) earn about 5% mass: small in a bridge cover, but it is worth noting in the shelings and manipulation. Graph/Enr
After Asked about design implications, Mcalpine wrote in an email that “the weight per unit of length of receiving stainless stain is the same as the conventional receiving”.
He said that the cover can be reduced “according to Aashhto LRFD” compared to carbon steel or receiving epoxy coated, and that, by placing a third -party test, the length of development “is the same as conventional receiving” because the force of steel trust link was 3% to 4% of carbon steel bar.
A report from the University of Nebraska -Lincoln de March 2025 found an average proportion of 0.96 bonds, which led to the stainless childhood bar, reached 96% of the output force of the conventional bar, and recommended maintaining the development and splicing lengths identical to the standard reinforcement.
“We have designed it to bring us exactly as conventional receiving in the countryside, the revolts of the same, the same specifications, so that the engineers are not disseminating the basic foundations, they are only gaining resistance to corrosion,” said Mcalpine. He said that receiving can be doubled just like carbon steel fight and does not have its protection to receive stainless tie ready to be installed, as it should be done with processes such as the carbon galvanizing steel bar with a zinc coating.
Mcalpine argues that the receiving co-oxy recovered is prone to cathodic damage and overflow: Florida and Virginia transport departments have stopped using it on new motorway bridges, and that galvanization is sacrificed and limited by time.
“Polymer coatings are easy to damage and can stand,” he added. “Our stainless layer is linked metallurgical so you don’t get this cathode overflow problem.”
Mcalpine cites a conference from the University of California, Berkeley’s corrosion expert Thomas Devine in the failures of the 2008 San Francisco San Francisco bar, as a care story. According to Devine’s analysis, high resistance seismic rods were placed in acid before galvanization, traping hydrogen in steel and causing the company when workers twisted them. The fractured screw heads of the rods could not be eliminated, despite the fact that the underlying steel remains intact.
“This failure taught us that corrosion resistance is not only about coating material, but also how Mcalpine said, emphasizing that the Allium process prevents the collection of acids and metallurically united the stainless layer in a single step.
Critics counteract that many corrosion problems come from cracks, thin roofs or poor details, not the base steel.
“Cracks allow direct access to oxygen, humidity and chlorides to the surface of the bar, and corrosion often begins at the fissure or nearby tips,” says Kevin Yuers, vice president of Kryton International Product Development, a van -based manufacturer of comprehensive crystalline adstrics. Her sister, Kari Yuers, president and CEO of the firm, adds that, while advanced bars have value, “cost, availability and familiarity limit widespread adoption; diminishing concrete permeability can be a cheaper way to protect reinforcement steel.”
As FHWA manual notes, “early measures included reducing the water-water relationship and increasing concrete coverage on reinforcement bars”, and a 2014 Iowa dowry study found: “No corrosion signs were observed in the receipts collected from without receiving places.”
Skeptics also cite old examples, such as the Alvord Lake Bridge of 1889 in San Francisco, which has been in minimal maintenance since 1889. Mcalpine says that the structure avoided the current dominant failure mode: Expansion of steel embedded in chloride in reinforced concrete.
The most famous example of the longevity of a steel bridge is the Eads bridge in St. Louis, the first bridge in the world of steel in the world, completed in 1874. The top wood cover of the steel wood of the EADS bridge closed in 1991 for extensive repairs after staying for 117 years. It was reopened on July 4, 2003, with a new concrete cover presented on its 129th anniversary, according to the American Galvanizers Association.
Allium says that it currently produces about 2,000 tonnes a year, linking the invoices to Massachusetts and rolling them with Mills to maintain a domestic supply chain. Jepeal said that typical schedules are less than six weeks for common sizes.
The company raised $ 3.25 million in March 2024 from Propeller, AERA VC and Anthropocene Ventures to climb production. Objective markets include bridge and traffic infrastructure, marine and coastal works, pavements and parking structures: places where chloride attack is common, while research and development are exploring rails, structural forms and batteries.
Several points remain unresolved. Caltrans has not yet published evaluation data; Corrosion, life cycle and allium carbon reduction, from maintenance, no longer require, they still have no independent review; And his statement that designers can reduce coverage under Aashhto LRFD awaits confirmation of the agency. These answers, once they arrive, will show if the stainless link is a niche solution or a new default value.
