In 1884, Ernest L. Ransome was awarded a product patent for twisted iron rebar that would be embedded in concrete as reinforcement. Concrete is capable of supporting heavy loads in compression, but is comparatively weak in tension. Ernest’s patented product later become known as Ransom bar. One of the first structures he reinforced with it was the Japanese Bridge located in New York (photo below right). In 1903, the first concrete high rise in America, called the Ingalls building, was reinforced with Ransome bar and still stands in Cleveland, Ohio today (photo below). Thousands of structures were reinforced with Ransome bar until the 1940’s in the US. While evidence suggests Ransome bar was used in some countries until the 1980’s, today’s deformed rebar is easier and less expensive to make so it eventually replaced Ransome bar everywhere.
Dr. Antoine Naaman mentioned Ransome bar in his publications about his research on small twisted wires mixed into fresh concrete to make a concrete steel composite with greater tensile strength than ordinary concrete. Even though they were essentially mini ransom bars, Dr. Naaman’s innovation of size and strength resulted in the award of two patents in 1999 and 2000 for all optimized shapes and geometries of twisted steel fibers for use in concrete. In 2003, one of Dr. Naaman’s research assistants formed a company and obtained a license from the University of Michigan to commercialize the patented technology. As early as 2006 and possibly earlier, concrete contractors started successfully reinforcing concrete with it.
After nearly two decades of use in reinforcing concrete it’s no surprise to find mini Ransome bars in all kinds of concrete structures. The high strength pieces of twisted steel wire generally range in length from a half of an inch to two inches long. They are also known by various names and acronyms. Twisted Steel Reinforcement is made from high tensile twisted steel wire and shouldn’t be mistakenly categorized with plastic and smooth steel wire fibers as they have different performance characteristics. The well established, high performance, of Twisted Steel Reinforcement (TSR) put in a category of its own.
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SteelX research developed a second generation TSR with a different cross section, coating, and tensile strength resulting in superior composite performance. The legacy of Ernest L. Ransome’s work continues to inspire innovation 137 years later.