Hemp rebar could be eco-friendly alternative to easily corroded steel


Researchers at Rensselaer Polytechnic Institute (RPI) in the United States have developed a hemp-based alternative to steel rebar. Researchers believe that the new option can avoid corrosion while reducing carbon emissions from construction, according to a report published by Dezeen.

Hemp rebar can be used to hold concrete structures in the same way as steel and other currently used rebars, but with a lower environmental impact because of its longer lifespan and hemp’s effectiveness at sequestrating carbon dioxide.

The research is leaded by RPI professors Daniel Walczyk and Alexandros Tsamis, according to whom steel rebar corrosion is currently a substantial contributor to the premature decay of structures such as bridges, highways, seawalls, and buildings.

“The American Society of Civil Engineers gives the concrete structure a lifetime of 40 to 50 years due to corrosion,” said Tsamis. “If the rebar didn't corrode, the lifespan would be three times as much, and it would have a huge overall contribution to reducing carbon emissions.”

Traditional steel rebar has a low embodied energy, according to the RPI team, especially if it is constructed with recycled content. However, the statistic masks the influence of its service life and maintenance requirements.

In severely corrosive conditions, structural designs may frequently adopt alternatives to standard steel, such as glass fiber reinforced polymer (GFRP) rebar, which has a high environmental effect.

Although the work has yet to be peer-reviewed, the team claims that preliminary studies reveal hemp rebar has a lower embodied energy than GFRP rebar while being likely as long-lasting.

This method is also expected to reduce construction time. Unlike other available non-corrodible options, Walczyk and Tsamis anticipate it to be more cost-competitive than ordinary steel rebar.

Industrial hemp is a type of cannabis sativa plant with a low concentration of the psychotropic component THC. Its fiber is one of the strongest among all plants, as strong as glass fiber, and it can sequester carbon dioxide from the air at twice the rate of trees.

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