Corroding steel in buildings could become a thing of the past, thanks to a new development at the Rensselaer Polytechnic Institute in New York, USA where researchers have invented a hemp rebar to replace steel in concrete structures.

Developed by Alexandros Tsamis, assistant professor of architecture and associate director of the Center for Architecture Science and Ecology (CASE), and Dan Walczyk, professor of mechanical engineering and director of the Manufacturing Innovation Center, the new composite rebar material is made from hemp fibres and bioplastics, and offers a viable alternative to steel rebar typically used as reinforcement during the construction of concrete structures such as buildings and infrastructure.

Steel reinforcement has a critical role to play in the structural integrity of buildings with the rebar providing tensile strength to the structure; however, steel is also at risk of corrosion when exposed to moisture, leading to the weakening of the structure with catastrophic consequences.

The hemp-based natural fibre-reinforced thermoplastic rebar developed by the researchers eliminates risk of corrosion, with its durability extending the lifespan of concrete structures. Comparable in strength to steel, the new hemp rebar will also contribute to lowering carbon emissions associated with the production of conventional steel.

The research is being conducted at the newly created Rensselaer Polytechnic Institute for Energy, Built Environment, and Smart Systems (EBESS). According to Rensselaer president Dr Shirley Ann Jackson, a major focus of this Institute will be to create new processes and products that drive decarbonisation of the construction industry, in this case by helping to incorporate industrial hemp into New York’s built infrastructure.

The researchers are now working on developing a machine that will make the hemp rebar on demand at any construction site. Key challenges such as the availability of industrial hemp and the relatively new field of bioplastics mean that the adoption of hemp rebar in the construction industry is still a few years away.

Image: Rensselaer Polytechnic Institute

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