Trent University has a goal to store more carbon in the building materials of their new Forensics Facility than was emitted in making the materials. In order to offset the inevitable emissions from harvesting and manufacturing materials it is necessary to use biogenic (plant-based) materials that store carbon in the material.
Hemp is the plant-based material of choice for this project. We chose two hemp-based materials for the Trent Forensics facility: Just Biofiber hemp blocks to be the load-bearing walls of the building and NatureFibres hemp batts to insulate the stud wall cavities. This post will focus on the Just Biofiber blocks.
Just Biofiber hempcrete blocks are a new product being manufactured in Alberta, Canada. The blocks consist of a plastic frame around which hempcrete is cast and cured. The blocks look and act much like large Lego blocks, with the eight posts on the top of a block fitting into holes in the bottom of the block above.
The Just Biofiber blocks provide enough load-bearing capacity in the plastic frames to be the structural wall for the building, and offer R-21 of thermal performance. A mortar made from lime and chopped flax is used to seal between each block and glue is applied to the plastic posts to attach the blocks together.
We were excited to work with Just Biofiber hempcrete blocks, having watched the company go through initial development and testing very closely. In practice, we found the system had a few key flaws. Firstly, the glue that is required is smelly, toxic and messy. Our crew truly despised working with the glue. Secondly, the Lego-like fit between the blocks made for a fussy installation as the tolerance is around 1/8-inch and if the foundation isn’t perfectly level a lot of work is required to ensure the blocks actually fit. A lot of dry-stacking is required to ensure a fit, and shimming was constant throughout the process. Finally, there are threaded rods required within the blocks and these were fussy and slow to install. The relatively low thermal performance of the blocks required us to add a frame wall with more insulation to meet our R-40 target.
We loved working with a hempcrete product that didn’t require site mixing or a lengthy drying process, but feel that the Just Biofiber hempcrete blocks need more development before they are a cost-competitive and easy-to-install system. We hope to see Just Biofiber continue to innovate and improve their system and look forward to a chance to work with the product again in an updated form.
The professional association representing the US hemp building industry moved forward to certify hemp and lime (hempcrete) insulation in US building codes this month.
Hempcrete was submitted as an appendix in the International Residential Codes on Jan. 10 by the US Hemp Building Foundation, the non-profit arm of the US Hemp Building Association.
The idea is to give U.S. building permitting departments a familiarity with the material, which is new to the United States after hemp was legalized under the 2018 Farm Bill.
“These documents will show a pathway for using hempcrete as a building material,” USHBA President Jacob Waddell told HempBuildMag. “The goal is to allow you to build with hempcrete without needing an alternative material variance,” he added.
An international committee of hemp building experts and advocates prepared the paperwork to submit to the International Code Council. IRC code experts will evaluate the paperwork in March and again in September to enshrine hemp + lime as an approved natural building material.
Eventually, inclusion in the IRC should “allow for hempcrete to be accessible to the standard person to construct with it,” Waddell said.
Hempcrete, a non-structural insulation made of hemp hurd (shiv) and lime binder, provides a superior insulation product when installed up to 1 foot thick in wall assemblies. The material is vapor-permeable, thermally regulating, fire resistant and and repels mold and pests. Hempcrete insulation is carbon negative due to the large amounts of carbon sequestered by the hemp plant via photosynthesis while growing.
Used widely in Europe
The US building industry has some catching up to do when it comes to the international use of hemp in building materials.
Right now in the United States, builders, engineers and architects who want to use hempcrete must gain approval project-by-project in the absence of an overarching national code to point to, said Texas-based developer Ray Kaderli, of the Hemp Build Network.
Kaderli’s company was just permitted by the city of San Antonio to build a hempcrete-insulated three-bedroom/two-bath 1,300 sq. ft. home.
Kaderli, a member of USHBA, praised the organization for moving forward with certification for hempcrete.
“With a new industry there are many things to do,” Kaderli said in an email. “This was one of the most important first steps. I’m grateful [USHBA] had the insight and discipline to focus in this direction.”
The certification process also leads the way to apply to certify hempcrete in the International Commercial Building Codes for commercial buildings in 2024, when the next application process begins, USHBA president Waddell said.
The material still needs to pass various ASTM fire tests as well as tests for structural bracing, Waddell said, for which the foundation will continue to raise funds.
Straw bale builders paved the way
USHBA hired engineering and natural building consultants, including two straw bale construction pioneers who helped get straw bale construction certified in the US residential building codes in the early 2000s.
Right now, the application submitted to the IRC only includes one-story structures to be insulated with hempcrete wall assemblies without extra engineering. This is a start that will be built upon to expand hempcrete’s role in the building codes, as more data and research is submitted and approved, Waddell said.
“Submitting to the IRC is just the first step in a very long process to get hempcrete where we’re able to use it more readily,” Waddell said.
The USHBA has about 200 active members and raised about $50,000 through its foundation for certification expenses and a series of other projects, including workforce development and creating educational materials, Waddell said.
The organization will host a members-only online event on Saturday, Jan. 30, where more information about the IRC certification will be shared.
The Massachusetts building permit official who approved one of last year’s largest hempcrete projects built on US soil last year, was initially confused at the rough inspection of the Cape Cod Hemp House, said Mary Dempsey, of Mpactful Ventures.
“The building inspector took one look and said, ‘Wait a minute where’s your plywood?’ Then he muttered, ‘I gotta go study these plans better,’” she told HempBuildMag.
Even though the Cape Cod Hemp House relied on engineering approval and didn’t have difficulty getting a permit, Dempsey said including hempcrete in the IRC codes will help local building permitting authorities better understand how it works and what it can and cannot do. Mpactful Ventures and Dempsey helped steer the USHBA study group to gather the paperwork and research together to submit to the IRC.
“People from all over the world were helping by reading this [document] to hopefully move an entire industry forward,” Dempsey said. “I’m really proud to have been part of it.”
Jean Lotus is editor and publisher of HempBuild Magazine.
Let us think of the comparative strength of a metal known to be strong and a hemp plant fiber. Which do you think would be stronger? You’re tempted to say hemp. But is hemp stronger than steel? The comparative strength of steel and a plant fiber, let us say. What would be your common-sense response? We actually asked this question randomly to a number of people of different age-groups. We simply wanted to check whether our intuitive response matches with theirs. It did. Almost everyone said – steel would be stronger. Only two people refused to answer. They believed there was a trick in the question somewhere. The common-sense response would be correct in most cases. With one exception: hemp fiber. Fibers from this non-narcotic variety of Cannabis Sativa can be stronger than steel, experts have demonstrated.
By Way of Clarification
You have read right: hemp does belong to the same plant species as the drug cannabis or marijuana: Cannabis Sativa. However, hemp is not a drug. It cannot give you a high. Hemp does not have more than 0.3% tetrahydrocannabinol (THC) to do that. THC is the substance with psychoactive qualities, present in the narcotic cannabis at a concentration level of 7.5-10% or more. Hence the mind-altering capacity of cannabis or marijuana. Hemp is clean.
Is hemp stronger than steel? The Truth – Revealed
Strength in scientific terms gets calculated in two different ways mainly. Hemp fibers have been studied from both of these ways of measuring strength. Counter-intuitive though it seems, hemp fiber has proven to be stronger than steel from both these angles. Below, we describe in detail how that is possible.
Tensile and Compressive Strength
Tensile strength is the ability to withstand tension. Compressive strength is the ability to endure compression. In other words, how much tension or tautness can something take before it gets permanently deformed? That is the tensile strength of that material. For example, how much pulling can a rope endure before it tears? That is the rope’s tensile strength. To tear is to get permanently deformed. It could also be measured in terms of weight endurance. For instance, how much weight can a tree branch take before it cracks and breaks? The weight at which the tree branch cracks and breaks is beyond its tensile strength threshold. The maximum weight it can endure is indicative of its ultimate tensile strength. Similarly, how much compression can something take before it loses its capacity to mend itself? That is compressive strength. Think of spring in this context. Normally, a spring will bounce back to its own shape as soon as you remove the pressure you are applying to it. However, it is also possible to keep squeezing a spring until it is no longer able to regain its own shape. The degree of pressing a spring can take without losing its shape permanently is its compressive strength. In simple terms, the pressure something can withstand before cracking and breaking or tearing is its tensile strength. The force applied takes the form of pulling at both ends. It can also take the form of piling on increasing amounts of weight on something. till it cracks and breaks. The amount of pressure something can endure without bending and losing its shape permanently is its compressive strength. The force applied in this case takes the form of pushing from both ends.
The Tensile Strength of Steel
Metallurgy, the science of metals, mentions steel to be one of the strongest metals. Strictly speaking, steel is not metal as it is an alloy of iron and other elements, among which carbon is a non-metal. That does not make a difference to the strength of steel, though. There are different varieties of steel with varying tensile strengths. The weakest form of steel is plain carbon steel with a tensile strength of up to 150 MPa. The strongest variety is ausformed steel with 3000 MPa of tensile strength.
The Tensile Strength of Hemp Fibers
In an article published in 2003 in the Materials Research Innovations, the authors report extensively on the tensile strength of hemp fibers of different diameters. The general rule in the case of synthetic fibers is that a reduction in the diameter of the fiber also decreases the faults. That implies a lesser diameter of synthetic fibers gives it higher tensile strength. Authors Prasad and Sain demonstrate in their article that this same principle is applicable to hemp fibers also. Hemp fibers with a diameter of 4 μm (micrometer) have a tensile strength of 4200 MPa. In contrast, the tensile strength of hemp fibers of 66 μm is 250 MPa only. The extensive experiments by Prasad and Sain demonstrate that the thickest hemp fiber with the least tensile strength (250 MPa) has more tensile strength than the variety of steel with the least tensile strength (150 MPa). Their experiments also demonstrate that the thinnest fibers of hemp with the maximum tensile strength (4200 MPa) is stronger than the steel variety with the highest tensile strength (3000 MPa). The range of tensile strength possessed by hemp fibers of different diameters is, thus, more than the tensile strength range of different varieties of steel.
Is hemp stronger than steel? A Simpler Explanation of the Answer
It is possible to explain the above feature of strength in simpler terms, without using the scientific jargon ‘tensile strength’. It will take a lot more pressure to crack or break composite materials made of hemp fibers than the amount of pressure needed to crack or break things made of steel. This is true across different varieties of steel and varying diameters of hemp fibers. The weakest hemp fiber needs more pressure to crack and break than the weakest variety of steel. The strongest variety of steel needs less pressure to crack and break than the strongest variety of hemp fiber. Hemp has the capacity to endure double the weight of steel before it cracks and breaks. That is how much stronger hemp is than steel.
The Compressive Strengths of Hemp and Steel
The ability of hemp not to bend to compression is nearly six times that of steel, experts say. From the angle of compressive strength, therefore, hemp is six times more bend-resistant than steel. That makes hemp stronger than steel from both aspects of strength measurement. The next time someone asks you – Is hemp stronger than steel? You can confidently answer – hemp, and then educate everyone on ‘how’ it’s stronger.
Strength Measurement in Applications
On June 19, 2017, CNBC reported on an episode from the “Jay Leno’s Garage’ show, where Leno drove a sportscar named Renew. Former Dell executive Bruce Dietzen got this sportscar specially made for himself out of 100 pounds of hemp fibers. Both Dietzen and Leno punched the car with considerable force several times. Their hands were hurt, but there was no dent in the car, unlike a car with a steel body. According to the owner, his hemp car is 10 times stronger than any car made of steel.
A 2018 article in Material Science recommends the use of hemp cables instead of cables made of harmonic steel for roofs with hyperbolic paraboloid cable nets. According to the author, this substitution would be both cost-effective and environment-friendly without involving any compromise in the strength aspect. News 18 reported on August 26, 2019, that the Canadian Hempheath Group has devised the world’s first aircraft made entirely from hemp. This four-seater plane has everything, from the wings to the body, the seats, and pillows are made from hemp. The company intends to run it on hemp biofuel also. Hemp’s superior ability to endure more weight than steel and its considerably higher bendability makes it 10 times stronger than steel, says the founder of the company.
From stalled legislation to falling stock prices, cannabis didn’t have the greatest year. But investors are finding something to be optimistic about heading into 2022: industrial hemp.
Demand is poised to rise for hemp — the staid sister to the mood-altering forms of cannabis — as it’s increasingly adopted for a wide range of uses, including concrete blocks, clothing and even car parts. The shift is driven by environmental incentives such as carbon caps and single-use plastic bans, which are making some natural materials preferable to those made from petrochemicals.
“Industrial hemp is the biggest opportunity in the cannabis sector as a whole,” said Mina Mishrikey, a partner at Merida Capital Partners. His firm has invested around 90% to 95% of its $500 million in assets under management in cannabis businesses centered around THC, the psychoactive ingredient in marijuana, but aims to make more investments in industrial hemp, Mishrikey told me.
Hemp could use the boost after the market struggled to capitalize on the hype following the 2018 farm bill, which legalized hemp and led to over-planting when not enough companies were ready to create end products. In 2021, the number of acres of hemp planted fell to 33,844 from 70,530 a year earlier and 465,787 in 2019 according to New Frontier Data.
Adding to the challenges, the U.S. Food and Drug Administration recently refused to regulate one of hemp's best-known products — CBD, or cannabidiol — as a dietary ingredient, casting a specter of uncertainty over the otherwise booming market for creams, tinctures and gummies.
As a material, hemp remains more expensive than alternatives that come from petrochemicals. But India, Canada, Germany and South Africa are among the countries cracking down on plastics in 2022, making alternatives more economical. Meanwhile, pressure to shift from oil and gas to renewable industries is increasing and carbon credits are becoming more valuable — and that’s an area where hemp has an advantage.
Mishrikey sees the plant’s ability to capture carbon while it’s growing, and its ability to use less water than cotton, as key factors that help it disrupt a range of products. Just one category of industrial hemp alone — precast concrete — is worth around $20 billion, roughly the same size as the current U.S. legal marijuana market, he pointed out.
His fund’s investments include Canadian Rockies Hemp Corp., based in Bruderheim, Alberta, which processes hemp for use in textiles, pulp and paper, animal bedding, rope, composites and automobile components, according to its website. Another is Bast Fibre Technologies Inc., based in Victoria, British Columbia, which has a processing technology to make nonwoven fabrics with natural fibers including hemp. That could be helpful for the booming market in wipes, which are ripe for disruption due to the sewer-clogging gobs known as fatbergs.
Hemp could play a role in many categories: plastics, textiles, papers, building materials, protein for humans and animals, and concrete of all forms. Some of the more innovative applications include hempcrete, where hemp fibers are infused in the mortar, and a Porsche car with some components made of hemp. Some see hemp as a viable alternative to almost anything made from petrochemicals, due to the properties of its cellulose fibers.
The U.S. will have some catching up to do: China is the leading grower of hemp and is tiptoeing into the CBD market, starting with Hong Kong. The plants also require different agricultural and processing techniques compared to other forms of cannabis, meaning the supply chain will have to be built out from scratch. Processing the plant's tough fibers, called decortication, is an arduous practice that takes heavy machinery and has created something of a bottleneck.
That bottleneck is about to get some help from a $500 million impact fund by rePlant Hemp Advisors, launched in early November by Geoff Whaling, co-founder of Collective Growth Corp., and others including Michael Woods, former chief executive officer and chief operating officer of Rothschild & Co. Asset Management U.S. The fund plans to help develop U.S. infrastructure to process hemp and improve the supply chain, focusing on hemp for food and fiber.
“I probably have a dozen companies call me a week” about using hemp in their products, Whaling said, citing brands like Chobani, Wrangler jeans and Tesla.
“They all want to know where they can get 100 tons of fiber a year, and the answer, at this point, is nowhere,” he said. “No major manufacturer will sign unless there's a two-year supply in a warehouse.”
But slowly, that’s changing.
“We're seeing more countries advancing and mandating use of sustainable fibers, more auto companies adopting natural fiber solutions,” Whaling said. “It really is an industrial hemp revolution.”
Number of the week
16.6% The compound annual growth rate of the legal U.S. cannabis market from 2020 to 2025, as estimated by New Frontier Data in their 2021 Year in Review report.