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New Hemp-Based Rebar Could Act as Sustainable Construction Cement Alternative

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Advocates and those working closely with the crop have consistently advocated for the versatility and potential benefits of hemp. Now, a newly developed alternative to steel rebar, made from hemp, could be the next hemp product to take off, as the product is low-cost, non-corroding and helps cut carbon emissions, according to a Dazeen report.

Researchers at the Rensselaer Polytechnic Institute (RPI) crafted the rebar alternative, which could be used to support concrete structures in the same way as steel and other rebars do today, though it would provide a reduced environmental impact because of its material makeup and lifespan.

The hemp rebar is made of intertwined natural hemp fiber that has been encased in thermoplastic, resulting in a strong, highly durable and corrosion-resistant reinforcement for cement-based construction projects.

Project leads Daniel Walczyk and Alexandros Tsamis told Dezeen that the steel rebar often used today contributes significantly to the premature decay of structures like bridges, roads, seawalls, and buildings.

Tsamis, who is also an architect and assistant professor at the RPI, said that environments with high salt concentration lead to faster corrosion, and concrete structures are often given a lifetime of 40-50 years.

“If the rebar was not corroding, it would be three times that much, and that would create a significant overall contribution to cutting carbon emissions, because you have three times more service life for every single thing you make,” Tsamis said.

The RPI team said that traditional steel rebar has a relatively low amount of embodied energy, especially if it is made of recycled content, and that this number conceals the impacts of steel rebar’s service life and maintenance needs.

The research team believes that the hemp-based rebar will match the strength and reliability of steel rebar and surpass it in terms of environmental impact and overall efficiency. An additional bonus, this process should decrease construction time. Walczyk and Tsamis also intend for the hemp rebar to be cost-competitive with, or even cheaper, than standard steel, which is typically not the case for other, non-corrodible alternatives currently available.

Ultimately, the team’s goal is to make the product the “obvious choice” even for projects without huge budgets or sustainability goals. This led to the design of the on-site pultrusion machine, which would forge the hemp rebar on-demand, on-site, with a sort of “John Deere” aesthetic.

“Rebar is an everyday material,” Tsamis told Dezeen. “It is a material that needs to be communicated to every contractor, every builder in every village everywhere in the world. So this is on purpose a kind of John Deere-like, ‘the people’s machine.’”

Their work has yet to be peer-reviewed, though Walczyk and Tsamis, along with their student collaborators Daniel Cohen and Sharmad Joshi, hope to publish their first paper on the technology next year. Until then, the team plan to continue developing and testing the rebar, along with a suite of other product, material and process innovations they are working on, with the broader goal of developing next-generation building technology through hemp.

A press release notes that this hemp research is among the first projects to come from the new Institute for Energy, Built Environment, and Smart Systems (EBESS) at Rensselaer.

“By harnessing the expertise in design, engineering, and business across the university, EBESS is developing a holistic plan for a sustainable and economically viable hemp industry that can help to reduce the carbon footprint of built environments and have a real impact on tackling climate change,” the release notes.

Many have looked to hemp as a building material alternative, especially as weather and climate disasters continue to persist. Fortress Home Co-Founder and Project Director Volodymyr Barabakh said that hemp works particularly well in damp, humid conditions because it’s more breathable than concrete and that areas more prone to floods, hurricanes and humid summers could see the benefits from hemp-based materials.

“From a purely structural standpoint, there is definitely a use case for hemp concrete for disaster rebuilding projects,” Barabakh stated.

Though, the main issue that prevents hemp from becoming viable for most projects involves costs and regulations, essentially that we’re just not quite there yet.

Jeff Sampson, founder and CEO of the THC and CBD marketplace Everscore, believes that hemp should be in the mix when looking to build sustainable structures and told High Times, “To increase our overall market share, we need to increase the recognition of hemp as a viable high-performance building material,” he said.

It’s an immense task, but he believes the industry can achieve the goal if everyone works together. This new development from RPI may very well play right into this conversation in the road ahead.