The concrete industry is all over the news these days. Its efforts to reduce and minimize its carbon footprint are groundbreaking, and offer new possibilities for fighting climate change. Concrete is also expanding into new and interesting niche markets. Most importantly, concrete will have a center-stage role in repairing and replacing U.S. dams, bridges, airports, and other essential components of our country’s infrastructure.

Since the early 1900s, skyscrapers and other structures referred to as ‘built to last’ have been made with reinforced concrete. After a bell tower built using reinforced concrete survived the 1906 San Francisco earthquake, its reputation as the standard in strength and reliability was established. The recipe for ‘rebar,’ as it is commonly known, hasn’t changed much over the past 100 years; however, crumbling infrastructure reveals unforeseen problems with the traditional rebar used to build our aging dams and bridges. Reinforced concrete is going to need an upgrade going forward. To understand why, it’s helpful to know the back story.  

Strengthening concrete with fibers dates back to ancient times; horsehair and straw were used in mortar and mudbricks. In the 1900s, asbestos fibers were used, until it was found to be a health risk. Steel, glass (glass fiber reinforced concrete) and synthetic fibers were in use by the 1960s. Today, innovators, manufacturers and researchers are exploring new ways to improve rebar and find better ways to manufacture it.

Why does it need to be improved? 
Concrete structures usually require major repairs after 20 years; they need maintenance every five years. The major cause of structural problems or complete failure is corrosion. Concrete is porous. When moisture gets in, oxidization causes the steel to rust, causing corrosion and ultimately leading to the concrete cracking and breaking away from the structure. Industry experts have tried sealants, chemical concrete additives, corrosion inhibitors, galvanized reinforcing bars, and using stainless steel bars to solve corrosion problems, to no avail.

New reinforcement materials like carbon fiber reinforced polymers and fiber-reinforced plastic offer great promise, but have, until recently, been too expensive to be potential replacements for steel in reinforcing concrete. These composite materials don’t behave the same way metal does; design specs have to be adjusted, and the science is complicated.

More widespread use is bringing down prices, and word is out on the many advantages these new materials have to offer. Industry experts that are refining these technologies and manufacturing alternate versions of rebar have new customers in the aerospace industry and the military, and remind would-be doubters that the whole-life cost will be price-competitive with steel-reinforced concrete. The list of selling points is impressive:

• At least one of the new reinforced polymer rebar products is reported to be stronger than steel
• It’s one-fifth the weight of traditional rebar – this means lower transportation costs, and it’s easier to carry and work with
• It requires 75 percent less energy to produce
• Fiber-reinforced plastic can be field-fabricated using basic carpenter’s tools with carbon or diamond tip blades.  No torches, no welding required
• More design options
• Unaffected by water and sub-zero temperatures

It’s exciting to imagine new concrete structures and repaired bridges and highways that will last longer than a human lifetime. Now that the innovators and manufacturers are on board and off to market, it looks as though nothing can stop this rebar revolution.