Passion, persistence and patience – winning the long game
The American Composite Manufacturers Association (ACMA) and others have been pushing for the widespread use of fiber-reinforced polymer (FRP) rebar in infrastructure construction for decades. Now, the industry is starting to see some major wins.
#perspectives-and-provocations #frprebar #infrastructure
It’s December, and winter is nigh in the Northern hemisphere. For many of us, it brings cold, snow and ice for the next several months. On the plus side, it means that another road construction season has passed, and with it, the disappearance of the ubiquitous orange barrels, detours and delays that accompany it. Come spring, they will be back, as there will inevitably be more failed bridges and roads to be replaced.
The reason for this? Cracked concrete, typically caused by rusting of the steel reinforcing rods, or rebar, used internally to strengthen the concrete. Over time and use, reinforced concrete develops small cracks, which allow water to penetrate. As water oxidizes the steel rebar, it expands up to four times its original dimension, putting internal pressure on the concrete, exacerbating the cracks, allowing more water to penetrate. The concrete eventually breaks apart, a process called spalling, which prompts eventual repair or replacement. Spalling is accelerated in chloride-rich environments, such as those where deicing salts are applied, and in coastal areas subject to seawater and salt air.
As a CW reader, you probably know the solution to this problem: Replace the steel rebar with one made of composites! Not only does composite rebar not corrode, it is 75% lighter and twice as strong as steel, as well as being electrically and thermally nonconductive. This solution seems obvious and easy, but change comes slowly to the infrastructure market, just as it has to commercial aircraft and automobiles. Composite rebar is more expensive than bare steel, yet compares well to epoxy-coated steel, and is cheaper than galvanized or stainless steel.
The German philosopher Georg Hegel one said, “Nothing great in the world has ever been accomplished without passion.” To that, I would add two other attributes necessary to effect change in conservative markets – persistence and patience. One person that exemplifies these three attributes is John Busel, Vice President, Composites Growth Initiative of the American Composites Manufacturers Association (ACMA). Because of the efforts of John, and many others, we are on the precipice of widespread adoption of fiber-reinforced polymer (FRP) rebar in infrastructure construction.
I sat down with Busel to better understand this journey, and what a long journey it has been! We in the composites industry typically see concrete as a material to replace; Busel sees it as an opportunity to enhance. In 1991 the American Concrete Institute (ACI) created ACI Committee 440, recognizing the emerging applications of composites in internal reinforcement with rebar and pre-stressed tendons and external reinforcement with column strengthening and seismic upgrade. In 1996, the committee developed a “state of the art” document regarding FRP use in concrete applications.
By the late 1990s, commercial FRP rebar products were introduced in field demonstrations. ACI issued a design guideline on composite rebar in its Emerging Technology Series in 2001, indicating this was a technology to follow. Busel chaired Committee 440 from 2004 to 2010, issuing seven standards in that time. ACI is very data-driven, and those early demonstrations provided field verification of the durability of composites, leading to removal of the “emerging” tag from the guideline in 2006.
ACI issued the current ACI 440.1R standard covering FRP rebar in 2015, and in 2017, ASTM issued a specification, ASTM 7957, covering testing standards and certification of FRP rebar. Committee 440 is currently authoring a dependent code to ACI 318, which covers all concrete structures, to incorporate the use of FRP rebar. While these documents are significant, what will truly drive market growth will be government buyers of roads and bridges demanding longer-life structures. Busel says many new projects in Canada today specify FRP rebar construction in bridges, and he expects this also will happen in the U.S. and elsewhere, creating huge opportunities for composite rebar manufacturers.
Busel gives significant credit for the acceptance of FRP rebar to the leadership and vision of Antonio Nanni, professor and chair of the College of Engineering at the University of Miami. Nanni has studied composite rebar for years and has provided data to ACI that proves the material’s long-term durability. Nanni also leads an effort to develop concrete mixtures using seawater instead of fresh water, initiating the SEACON project with US and Italian partners to demonstrate the technology at scale. FRP rebar is a key to success, as seawater contains 300-500 times the chloride content of fresh water. The implications for island nations and arid coasts where fresh water is in short supply is significant, to say the least.
Composites offer many advantages to improving infrastructure applications beyond rebar. If we continue to play the long game, we will prevail.
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