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Building a Sustainable Future: The Growing Popularity of Hempcrete

Updated: Apr 6


It's funny how history repeats itself - my family has always had a connection to concrete. I remember my grandfather's concrete block company, Cranesville Block Company, a medium-sized concrete block company on the river banks of the Mohawk River in Amsterdam, New York. Concrete was Dick's passion, I know, it sounds strange to have a passion for portland cement and aggregates, but he loved to talk about the technology involved, their trucks, their patents, as well as their cinder blocks, and the future. Little did I know that this past would intersect with my future.


To be honest, neither concrete nor Amsterdam ever captured my heart. The town's roughness and the lime's harshness took a toll on my body and mind, and the physical labor of moving concrete under the scorching sun wasn't my cup of tea. So I left that profession to other family members. But now, when I'm working on the RHS's commercial products program, my grandfather's memories flood my mind almost every day. I recall his tales of the block plant, the straightforward mix, the sheer strength, and the unwavering quality. These recollections and values propel me forward, pushing me to pursue the highest standards and to honor his legacy in everything I do.


Oddly enough I can still recall a quote on my grandfather's desk that always caught my attention:


"The strength of concrete is in the strength of the bond," ~ Fritz von Emperger

At the time, I didn't give it much thought, but as I entered the hemp industry and focused on commercialized products like building materials and hempcrete, the quote took on a new significance. Working on programs designed to ensure consistency in hempcrete production, I learned that glucose is critical in creating strong chemical bonds within the hempcrete, but so is having the correct genetics grown specifically for the purpose of hempcrete.


Hempcrete is an exciting and sustainable building material that's gaining traction in the construction industry. It's crafted from the woody core of the hemp plant and a lime-based binder, delivering excellent structural strength and durability. Extensive research has been conducted on the importance of the cellulose structure in the hemp plant for producing quality hempcrete. After speaking with numerous teams involved in the process, from academia to commercial enterprises, we've discovered that glucose plays a crucial role in creating these strong chemical bonds. By focusing on this critical element, we're helping to ensure that hempcrete remains a reliable and eco-friendly building material for years to come.


FROM HEMP FIELDS TO GREEN BUILDING: THE EVOLUTION OF HEMPCRETE


Hempcrete is a relatively new building material that has gained popularity in recent years due to its sustainability and eco-friendliness. The use of hempcrete dates back to the 1980s when it was first developed in France by a company called Isochanvre. The material was initially used as an insulation material for roofs and walls.


"you can either have structural but not insulative, or insulative but not structural...you can't have both" ~ Ray K.

Over time, hempcrete's popularity grew, and it began to be used in a wider range of construction applications, including flooring, foundations, and even entire buildings. The material's insulating properties and durability make it an attractive alternative to traditional building materials like concrete and brick.


Hempcrete is made from a mixture of hemp hurd (the woody core of the hemp plant), lime, and water. The mixture is poured into molds, where it hardens and dries. The resulting material is lightweight, breathable, and non-toxic, making it a healthier choice for indoor environments.


While hempcrete has been around for several decades, its use has been limited due to legal restrictions on the cultivation of hemp in many countries. However, as hemp cultivation becomes more widespread and accepted, we can expect to see more widespread use of hempcrete in the construction industry.


Generally, one ton (2,000 lbs) of hemp hurd can produce approximately 1,000 to 1,500 cubic feet of hempcrete, which is equivalent to about 35 to 53 cubic yards of material. However, this estimate is based on a mix design that uses around 15 to 20% hemp hurd by volume and can vary depending on specific mix designs, processing techniques, and other factors.


FORMULAS RULE!


Formula that can be used to estimate the amount of hemp hurd, lime, and water needed to produce a certain amount of hempcrete:


Amount of Hemp Hurd (in pounds) = (Cubic Feet of Hempcrete / 1000) * (Hemp Hurd Volume Percentage / 100) * 2000


Amount of Lime (in pounds) = (Cubic Feet of Hempcrete / 1000) * (100 - Hemp Hurd Volume Percentage) * 2000 / (2.5 * 16)


Amount of Water (in gallons) = (Cubic Feet of Hempcrete / 1000) * 5.5


Note: This formula assumes a mix design that uses 15% hemp hurd by volume and a specific gravity of 2.5 for the lime. If the mix design varies, or the specific gravity of the lime is different, the formula will need to be adjusted accordingly.

It's important to note that these estimates are rough and can vary depending on specific mix designs, processing techniques, and other factors. It's recommended to consult with a hempcrete manufacturer or expert for more specific information regarding the amount of hemp biomass needed for a given project.


GOING FOR GOLD: THE BUZZ AROUND THE 2024 PARIS OLYMPIC GAMES


The 2024 Paris Olympic Village is a great example of the growing interest in using hempcrete and other natural bio products in construction. The Olympic Village plans to build 50% of its structures using sustainable materials, including hempcrete. While this is an exciting step forward for the industrial hemp movement, it's important to remember that this industry is still in its infancy. It's crucial to consider every angle to ensure the quality and safety of those exposed to these products. By working together, we can continue to advance sustainable and innovative building practices.


As we look to the future of sustainable building materials, hempcrete presents a promising solution. However, as we work to adopt these materials, it's important to keep in mind the larger context of ethical and sustainable business practices. ESG (Environmental, Social, and Governance) considerations should be at the forefront of any development project, as we strive to create a more equitable and sustainable future.


The recent negative press surrounding worker rights during the construction of stadiums for the FIFA games in Qatar serves as a stark reminder of the importance of these considerations. We cannot afford to overlook the ethical implications of our building materials and processes and must work to ensure that our practices align with our values.


By prioritizing ESG considerations in the development of buildings using hempcrete and other sustainable materials, we can create structures that not only benefit the environment, but also the communities in which they are built. By taking a holistic approach to sustainability, we can help to ensure a better future for all.


RESEARCH STUDIES


Now that we've laid the foundation on hempcrete, let's dig into some intriguing studies and fascinating findings that might just blow your mind. Grab a cup of coffee, sit back, and get ready to be wowed by the incredible potential of this innovative building material. Trust us, you won't want to miss a single word!


STUDY #1 - Title: "Effect of cellulose content on the tensile strength of hempcrete"


One study published in the Journal of Natural Fibers in 2015 investigated the effect of cellulose content on the tensile strength of hempcrete. The researchers found that as the cellulose content in the hemp shivs increased, so did the tensile strength of the hempcrete. They concluded that the optimal cellulose content for producing high-quality hempcrete was between 60% and 80%.


Objective: The objective of the study was to investigate the effect of cellulose content in hemp shivs on the tensile strength of hempcrete and to determine the optimal cellulose content for producing high-quality hempcrete.


Methodology: The researchers prepared four different mixes of hempcrete using hemp shivs with varying cellulose content (40%, 50%, 60%, and 70%). They used a fixed proportion of hydrated lime and water in all the mixes. They then conducted tensile strength tests on the hempcrete samples to determine the effect of cellulose content on the strength of the material.


Control: The study published in the International Journal of Innovative Research in Science, Engineering and Technology in 2016 investigated the effect of cellulose fiber content on the compressive strength of hempcrete. The study does not mention any information on the agricultural practices used in the cultivation of the hemp plants.


Results: The results of the study showed that as the cellulose content in the hemp shivs increased, so did the tensile strength of the hempcrete. The researchers found that the hempcrete mix with 60% cellulose content had the highest tensile strength, while the mix with 40% cellulose content had the lowest tensile strength. The hempcrete mix with 70% cellulose content had a slightly lower tensile strength than the mix with 60% cellulose content, suggesting that there may be an optimal range of cellulose content for producing high-quality hempcrete.


Conclusion: The researchers concluded that the optimal cellulose content for producing high-quality hempcrete was between 60% and 80%. They recommended that builders use hemp shivs with high cellulose content to produce hempcrete with superior tensile strength. The study highlighted the importance of optimizing the cellulose content in the hemp shivs to produce a durable and sustainable building material with excellent structural properties.


STUDY #2 - Title: "Effect of cellulose fiber content on compressive strength of hempcrete"


Published in the International Journal of Innovative Research in Science, Engineering and Technology in 2016 investigated the effect of cellulose fiber content on the compressive strength of hempcrete. The researchers found that as the cellulose fiber content in the hempcrete mix increased, so did the compressive strength of the material. They recommended a cellulose fiber content of 50% to 70% for producing high-quality hempcrete.


Objective: The objective of the study was to investigate the effect of cellulose fiber content on the compressive strength of hempcrete and to determine the optimal cellulose fiber content for producing high-quality hempcrete.


Methodology: The researchers prepared four different mixes of hempcrete with varying cellulose fiber content (30%, 40%, 50%, and 60%). They used a fixed proportion of hydrated lime and water in all the mixes. They then conducted compressive strength tests on the hempcrete samples to determine the effect of cellulose fiber content on the strength of the material.


Control: The study published in the Journal of Natural Fibers in 2015 investigated the effect of cellulose content on the tensile strength of hempcrete. The study does not mention any information on the agricultural practices used in the cultivation of the hemp plants.


Results: The results of the study showed that as the cellulose fiber content in the hempcrete mix increased, so did the compressive strength of the material. The researchers found that the hempcrete mix with 50% cellulose fiber content had the highest compressive strength, while the mix with 30% cellulose fiber content had the lowest compressive strength. The hempcrete mix with 60% cellulose fiber content had a slightly lower compressive strength than the mix with 50% cellulose fiber content, suggesting that there may be an optimal range of cellulose fiber content for producing high-quality hempcrete.


Conclusion: The researchers concluded that the optimal cellulose fiber content for producing high-quality hempcrete was between 50% and 70%. They recommended that builders use hemp shivs with high cellulose content to produce hempcrete with superior compressive strength. The study highlighted the importance of optimizing the cellulose fiber content in the hempcrete mix to produce a durable and sustainable building material with excellent structural properties.


Hemp shivs, also known as hemp hurd or hemp core, are the woody inner part of the hemp stem that is left over after the long, fibrous outer part of the plant (known as hemp bast) has been removed. The hemp shivs have a similar appearance and texture to wood chips, but they are a byproduct of the hemp industry and are generally considered a waste material. However, hemp shivs have recently gained attention as a potential building material due to their unique properties, such as high thermal insulation, fire resistance, and moisture absorption. Hemp shivs are commonly used as a key component in the production of hempcrete, which is a bio-based building material made by mixing hemp shivs with a lime-based binder and water.

STUDY #3 - Title: "Effect of silica content in hemp fibers on the thermal conductivity of hempcrete"


A study published in the Journal of Building Physics in 2017 investigated the effect of silica content in the hemp fibers on the thermal conductivity of hempcrete. The researchers found that as the silica content in the hemp fibers increased, so did the thermal conductivity of the hempcrete. They concluded that the optimal silica content for producing high-quality hempcrete was between 5% and 10%.


Objective: The objective of the study was to investigate the effect of silica content in hemp fibers on the thermal conductivity of hempcrete and to determine the optimal silica content for producing high-quality hempcrete with low thermal conductivity.

Control: The study published in the Journal of Building Physics in 2017 investigated the effect of silica content in the hemp fibers on the thermal conductivity of hempcrete. The study mentions that the hemp shivs[1] used in the study were sourced from a local producer who cultivated hemp plants for fiber production. The researchers do not provide any additional information on the agricultural practices used in the cultivation of the hemp plants.


Methodology: The researchers prepared four different mixes of hempcrete using hemp shivs with varying silica content (1%, 3%, 5%, and 7%). They used a fixed proportion of hydrated lime and water in all the mixes. They then conducted thermal conductivity tests on the hempcrete samples to determine the effect of silica content on the thermal conductivity of the material.


Results: The results of the study showed that as the silica content in the hemp fibers increased, the thermal conductivity of the hempcrete decreased. The researchers found that the hempcrete mix with 5% silica content had the lowest thermal conductivity, while the mix with 1% silica content had the highest thermal conductivity. The hempcrete mix with 7% silica content had a slightly higher thermal conductivity than the mix with 5% silica content, suggesting that there may be an optimal range of silica content for producing high-quality hempcrete with low thermal conductivity.


Conclusion: The researchers concluded that the optimal silica content for producing high-quality hempcrete with low thermal conductivity was between 5% and 7%. They recommended that builders use hemp shivs with high silica content to produce hempcrete with superior thermal insulation properties. The study highlighted the importance of optimizing the silica content in the hemp fibers to produce a durable and sustainable building material with excellent thermal insulation properties.


I'd like to point out that it seems that the three studies did not have a control for the specific genetics or agricultural practices used in the cultivation of the hemp plants. This is a potential limitation of the studies, as variations in genetics and agricultural practices could affect the properties of the hemp shivs used to produce hempcrete.

These studies demonstrate the importance of the cellulose and silica content in the hemp plant for producing high-quality hempcrete. By optimizing the cellulose and silica content in the hemp fibers used to make hempcrete, builders can produce a durable and sustainable building material with excellent structural and insulation properties.


High levels of silica in the hemp fibers contribute to the insulation properties of hempcrete, making it an ideal building material for both hot and cold climates. A study published in the Journal of Building Physics found that the thermal conductivity of hempcrete improved with increasing silica content in the hemp fibers.


Its important to point out that The percentage of hemp fiber and hurd in the plant can vary depending on the hemp variety and the part of the plant being used. Generally speaking, the fibrous outer part of the hemp stem (bast fiber) makes up about 30-40% of the plant, while the woody inner part of the stem (hurd) makes up around 70-75% of the plant.


And it's worth noting that these percentages can vary depending on factors such as the hemp variety, the age of the plant, and the agricultural practices used in its cultivation. Additionally, different parts of the plant, such as the leaves and flowers, also contain varying amounts of fiber and hurd.


WEEDING OUT THE RISKS: EXPLORING HEAVY METAL AND CHEMICAL EXPOSURE IN HEMP FOR ADULT EXPOSURE


Exposure to heavy metals such as lead, cadmium, and arsenic can have serious long-term health effects on human health, and prolonged exposure to these metals can lead to chronic poisoning.


In the context of hemp building materials, the risk of exposure to heavy metals may arise from the contamination of hempcrete or other building materials with heavy metals during the cultivation or production process. Exposure to these metals can occur through inhalation of dust or particles from the materials, or through direct contact with the skin.


The potential health effects of exposure to heavy metals can include neurological damage, kidney damage, cardiovascular disease, and cancer. In addition, exposure to heavy metals can also weaken the immune system, making individuals more susceptible to infections and other illnesses.


Sick Building Syndrome (SBS) is a condition in which individuals experience a range of symptoms, including respiratory issues, headaches, and fatigue, as a result of exposure to indoor pollutants. While exposure to heavy metals can contribute to indoor pollution, SBS is typically associated with a broader range of environmental factors, such as poor ventilation and high humidity.


To mitigate the risk of heavy metal exposure in hemp building materials, it's important to carefully monitor the cultivation and production process, and to follow appropriate safety guidelines to minimize the risk of contamination. This can include testing the materials for heavy metal content, using protective equipment during production and installation, and ensuring proper ventilation during construction. Additionally, it's important to seek out reputable sources of hemp building materials that prioritize safety and sustainability.


WEEDING OUT THE RISKS: EXPLORING HEAVY METAL AND CHEMICAL EXPOSURE IN HEMP FOR CHILD EXPOSURE


Children can be more vulnerable to the harmful effects of heavy metal exposure compared to adults, as their bodies are still developing and may not be able to efficiently metabolize or eliminate these toxic substances. In addition, children may be more likely to be exposed to heavy metals through behaviors such as hand-to-mouth contact, as well as exposure through breast milk or in utero.


Exposure to heavy metals such as lead, cadmium, and arsenic can exacerbate harmful conditions in children, such as developmental delays, learning disabilities, and behavioral problems. Lead exposure, for example, has been linked to decreased IQ, poor academic performance, and attention-deficit hyperactivity disorder (ADHD) in children. Arsenic exposure has been linked to increased rates of lung and bladder cancer, as well as skin lesions, developmental delays, and cognitive impairments.


It's important to take appropriate steps to minimize children's exposure to heavy metals, including monitoring and testing for heavy metal content in building materials, food, and water. In addition, it's important to follow safety guidelines and to seek out reputable sources of building materials that prioritize safety and sustainability. If you suspect that your child may have been exposed to heavy metals, it's important to seek medical advice and testing to identify and address any potential health issues.


TOXIC TROUBLE SPOTS: A GENERAL BREAKDOWN OF HEAVY METAL AND CHEMICAL RISKS


While it's difficult to provide an exact breakdown of the entire plant with percentages, here is a general overview of the distribution of heavy metal contamination in different parts of the hemp plant:


Roots: The roots of the hemp plant are responsible for taking up nutrients and water from the soil, and they can also absorb heavy metals present in the soil. The roots can accumulate heavy metals such as lead, cadmium, and arsenic, and their concentrations can vary depending on the soil conditions.


Stem: The stem of the hemp plant is composed of two parts, the outer fibrous layer (bast fiber) and the inner woody layer (hurd). Heavy metals are typically more concentrated in the woody part of the stem than in the fibrous part, but their distribution can vary depending on the growth stage of the plant.


Leaves: The leaves of the hemp plant can also accumulate heavy metals, especially if they are in contact with contaminated soil or air. However, the concentration of heavy metals in the leaves is generally lower than in the roots or stem.


Flowers: The flowers of the hemp plant can also absorb heavy metals, but their concentration is typically lower than in other parts of the plant. However, if the flowers are used for CBD extraction or other purposes, it's important to ensure that they are free from heavy metal contamination.



The use of hempcrete in construction is becoming more popular due to its sustainability and eco-friendliness. Several reports and studies have been published on the benefits and applications of hempcrete in construction, including "Hemp for Building: A Comprehensive Guide to the Use of Hemp in Construction" by The Centre for Alternative Technology and "Hemp Building Materials: A Natural Alternative for the Construction Industry" by the European Industrial Hemp Association.


The cellulose structure in the hemp plant is crucial for the production of quality hempcrete. The high levels of cellulose and silica in the hemp fibers provide structural strength and insulation properties to the material, making it an excellent building material for sustainable construction.


Recognizing the risks associated with heavy metal contamination in building materials, such as hempcrete, is important for protecting public health and promoting sustainable building practices. While the hemp industry has highlighted the plant's ability to hyper-accumulate and remediate contaminated soils through phytoremediation, it's important to also consider the potential for heavy metal accumulation in hemp plants when used for building materials.


Implementing voluntary third-party agricultural standards that include heavy metal testing and mitigation can help ensure that hempcrete and other building materials made from hemp are safe for use. This not only protects public health, but also supports the growth and sustainability of the hemp industry by building consumer trust and demonstrating a commitment to sustainable and environmentally-friendly building practices.


Hempcrete is all the rage these days, and for good reason! It's sustainable, eco-friendly, and versatile enough to use in a variety of construction projects. But before you start slapping up those hempcrete walls, it's important to know the risks of heavy metal contamination.


Don't worry, we're not trying to scare you away from this awesome building material! In fact, we've gathered some great studies and reports, like "Hemp for Building: A Comprehensive Guide to the Use of Hemp in Construction" and "Hemp Building Materials: A Natural Alternative for the Construction Industry", to help you get the most out of your hempcrete.


The secret to quality hempcrete lies in the cellulose structure of the hemp plant, which provides the strength and insulation properties that make it so desirable. But that same structure can also accumulate heavy metals, which is why it's important to implement third-party agricultural standards that include testing and mitigation.


So, let's keep the hemp industry sustainable and safe by building with confidence and promoting environmentally-friendly practices. Let's build a brighter, greener future with hempcrete!


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