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What is Hempcrete - A Miracle Mixture

Updated: Aug 27, 2023

Key Insights

  • Bio-aggregate concretes (BAC) are formed by combining crop-based aggregate, mineral binder, and water.

  • Hempcrete or Hemplime, which is a bio-composite material, is a mixture of hemp hurds (shives) and lime, sand, or pozzolans, which is used as a material for construction and insulation.

  • In India, Hemp domestication dates back to 5000-4000 BC.

  • Cannabis sativa L. (hemp) has preserved the ancient artwork in India’s sacred Ellora Caves for 1500 years.

  • The processing of the Cannabis sativa results in three basic components namely shives or hurds (62 %), plant fibers (35 %), and seed and dust with particle size less than 0.5μ (4 %) by weight.

  • The cement industry alone is one of the largest carbon dioxide emitters (about 10%).

  • In 2016 A study conducted by Jami showed that hemp shivs are composed of 45% carbon, meaning 1 kg of hemp shivs sequester about 1.6 to 1.8 kg of carbon dioxide through photosynthesis during the plant’s growth.

Hempcrete block in white background

Have you heard about hempcrete? It's a fascinating bio-composite building material that's gaining popularity for construction and insulation. You might also know it as hemp-lime or hemplime. What's intriguing is that it's created by blending hemp hurds (or shives) with lime, sand, or even pozzolans.


What is Hempcrete

A crude comparison of the biodiversity friendliness of selected major crops and three Cannabis sativa crops (fiber, oilseed, drug) based on 26 criteria (after Montford and Small 1999a).
A crude comparison of the biodiversity friendliness of selected major crops and three Cannabis sativa crops (fiber, oilseed, drug) based on 26 criteria (after Montford and Small 1999a).

Have you ever heard of something called Cellulose Aggregate Concrete (CAC) or bio-aggregate concrete? It's a pretty fascinating concept! So, bio-aggregate concrete, also known as BAC, is a cool material made by mixing crop-based aggregate, mineral binder, and water. The result? A type of concrete that's not only lightweight but also offers fantastic thermal insulation and has a low carbon footprint. And what's really neat is that they can even toss in industrial waste like fly ash and slag into the mix, making it even more eco-friendly.


Now, within this world of bio-aggregate concrete, there's something called Hempcrete or Hemplime. This stuff is truly unique. It's a blend of hemp hurds (or shives) and lime, sand, or pozzolans. And guess what? It's used both for construction and insulation. Now, here's the twist: the cannabis plant, often associated with its psychoactive properties, used to be cultivated mainly for its super strong fibers. Those hemp fibers are like nature's durable gift for making fabric. But that's not all – they have some incredible properties. They're like natural insect repellents, can handle being wet without an issue, and they're excellent at managing moisture.


But wait, there's more! Hemp fibers can retain heat, regulate moisture, and even capture carbon dioxide. Plus, they're non-toxic, fire-resistant, and act as fantastic insulators. And get this – they're great at absorbing natural sounds, making spaces quieter and more peaceful. Isn't it amazing how something we might associate with something entirely different can have these incredible construction and insulation superpowers? And guess what? It even had a role in the art world. Picture this: the Ellora Caves, standing tall for 1500 years, thanks to hemp. It's like hemp had a hidden talent for preserving artwork, repelling insects, and keeping humidity in check.

Ellora caves top view
Breathtaking Ellora Caves Were Preserved by Hemp

Step right into the time machine, my friend, because we're heading back to ancient India, where the fascinating story of hemp unfolds. Back around 5000-4000 BC, imagine fields of hemp plants swaying in the wind, tended by skilled hands. But this wasn't just any plant – it was a true multitasking marvel.


These ancient Indians were onto something big. They didn't just plant hemp for one purpose; they were all about that holistic hemp lifestyle. They knew the stems were a goldmine of fibers, spun into fabrics and ropes that held their world together. And those tiny hemp seeds? They pressed them to extract edible oil, a delicious addition to their meals.


But hold on, because here comes the real plot twist: hemp wasn't just another plant in their garden. It was a superstar in their medicine cabinet. The ancient medical work "Sushruta" spilled the hemp secrets around 1000 BC. It wasn't just about coughs and colds; hemp was their go-to for everything from phlegm troubles to memory enhancement. Yep, you read that right. They believed it could sharpen memory, boost eloquence, and even help with stuff like gonorrhea. Talk about a versatile remedy!


Now, let's dive into the literary treasure trove of "Tajnighuntu" and "Rajbulubha." These ancient texts spilled the beans on even more uses for hemp. Not only did it have a knack for expelling flatulence (yes, really), but it was also their secret weapon against a grumbling tummy.

Three baskets showing bast fiber, hurd and green microfiber of hemp
https://canadiangreenfield.com/hemptrain/

Did you know that the stalk or straw of the hemp plant can be divided into two main parts? It's pretty cool – there's the "bast" and the "hurd." So, let's break it down. The stalk itself is made up of two things: fibers that are soft and flexible, and hurds that are rigid and tough. Now, these bast fibers are taken from the hemp straw through a process called retting, and they're used to make things like textiles, ropes, and cords. Neat, right?


Now, when you process the Cannabis sativa plant, you end up with three key components. First, there are these things called "shives" or "hurds," which make up about 62% of the weight. Then, you've got plant fibers, making up around 35%. And lastly, there's this smaller bit – about 4% – made up of seeds and really tiny particles less than 0.5 micrometers in size.


Here's the science behind it: that hemp hurds, the essential part of the Cannabis plant, are made up of a chain of cellulose, kind of like a long chain made of similar units. These chains are aligned by microfibrils. They're like the building blocks. And guess what holds them all together? Lignin, pectin, and hemicelluloses. These are like the glue that keeps everything in place.


What's really interesting is that the strength of these fibers mostly comes from a special kind of bond called a hydrogen bond. This bond forms between different chemical compounds in the fibers, giving them their strength. If you want to dive even deeper, you can check out this link: http:/hort.purdue.edu/newcrop/ncnu02/v5-284.html. It's amazing how this plant's parts work together to create such versatile and useful materials!


DID YOU KNOW?
Hemp shiv is one of the most widely used and studied plant particles for the manufacture of building materials, and hemp concrete is one of the most widely studied bio-based concretes.

Carbon Negativity of Hemp

So, in a study from 2014, they found out that just the production of cement in India had led to a massive 102 mega-tonnes of carbon dioxide emissions. This was about 4.4% of the total 2.3 giga-tonnes of carbon dioxide emitted in the country. It's interesting to note that the cement industry itself contributed around 10% of all carbon emissions.


To tackle this issue and find a more eco-friendly option, researchers suggest a shift to something called Cellulose Aggregate Concrete (CAC). This could be a game-changer because it's more sustainable and environmentally friendly.


Jumping to 2016, another study showed that hemp shivs, which are part of hemp plants, are pretty impressive carbon absorbers. About 45% of hemp shivs are made up of carbon. What's cool is that 1 kilogram of these hemp shivs can absorb around 1.6 to 1.8 kilograms of carbon dioxide while the hemp plant grows through photosynthesis.

Illustration showing CO2 absorption by hempcrete wall
https://www.sciencedirect.com/science/article/abs/pii/S0959652617303876

Now, let's talk about a specific example: a functional wall unit that's 1 meter tall, 1 meter wide, and 0.3 meters thick. This unit, made with hemp concrete, managed to absorb a whopping 82.71 kilograms of carbon dioxide. This not only compensated for the 46.43 kilograms of carbon dioxide emitted during the various processes like growing, manufacturing, and construction (you know, making lime, transporting materials, and so on), but it also stored an extra 36.08 kilograms of carbon. Essentially, these hemp concrete structures are offsetting all the carbon emissions from other building-related processes.


And it gets better! Some observations showed that 1000 kilograms of hemp can actually capture about 1500 kilograms of carbon dioxide. So, it's a pretty efficient carbon sequestration method.


But wait, there's more! Hemp can be grown strategically around areas that are heavily industrial and polluted. This can help purify the air and environment by absorbing a lot of the carbon dioxide around. Think of it as a natural air cleaner. Plus, you can find hemp growing alongside highways and congested traffic zones. This not only adds some greenery but also improves the air quality of those places.

Comparison of carbon footprint of natural fibres

In a nutshell, if we want to make buildings that don't add more carbon dioxide to the environment, using hemp concrete seems like a fantastic approach. It's not only compensating for emissions but also actively storing more carbon dioxide. And the idea of using hemp to clean up the air around polluted areas and busy roads is pretty innovative!


Conclusion

You know, cannabis hemp has been hanging around in our society for quite some time. It's been like this hidden hero, quietly doing its thing throughout history. It's been used to keep stuff safe, maintain things, and just generally keep things intact. It's kind of amazing how much it can do, but it's like we've been underestimating its power because of some old social beliefs.


But here's the deal: if we want to fix the mess we've made, we've got to make a speedy switch to stuff that's better for the environment. And that's where hempcrete comes into play. It's like the superhero solution for a brighter future. Seriously, it's got all these awesome qualities packed into it. It's got these natural powers that keep bugs away, it's like a pro at holding in heat, it's not afraid of water, and it can even handle moisture like a champ. Oh, and it's a carbon dioxide trap too - that's like a big thumbs-up for Mother Earth.


What's even cooler is that hempcrete doesn't mess around with toxins, it's not afraid of fire, and it's like a built-in insulator. Plus, it's got this secret talent of soaking up 90% of the annoying background noise. I mean, who knew, right?


So, bottom line, we've got this cannabis hemp that's ready to replace all sorts of materials if we give it a chance and sprinkle in some innovation and tech magic. It's like nature's own answer to a bunch of problems, just waiting for us to make the most of it. Time to let this green superstar shine!


CHOOSE WISELY

NOW IF ANYONE ASKS YOU WHAT IS HEMPCRETE, YOU KNOW WHAT TO SAY


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