What Is Hempcrete?
The Building Blocks of Green Construction
Our environment and its inhabitants need eco-friendly building materials and green building methods to combat the carbon emissions created by our current means of construction.
One such trending material (though discovered years ago) is disrupting the market and has come to be known as “hempcrete” (with the hope that it will replace concrete). This eco-friendly building block derived from the hemp plants is on the fast track to changing the way we build residential homes and commercial buildings.
In this article, we will walk you through an overview of what exactly hempcrete is, but we encourage you to explore the product deeper in the subsequent articles that provide more in-depth information on a wide array of topics.
What Makes Up Hempcrete?
Also, known as hemp lime, it is a bio-composite material and a natural alternative to concrete and traditional insulation. It is a mixture of hemp hurds and lime, but may also include natural hydraulic lime, pozzolans or sand. It is sold under names Canosmose, Canobiote and Isochanvre, though the term “hempcrete” is gaining mass traction in the consumer market.
Components of the Hemp Plant
Hemp is a variety of Cannabis Sativa plant and has been used for thousands of years for a number of industrial uses. It is said to have originated in Central Asia and its cultivation for fiber was recorded in China during 2800 BC.
Some examples of industrial hemp include textiles, paper, rope and beauty products. It is said that hemp has 25,000 different uses because it can replace materials found in 25,000 different applications. For example, hemp can serve as an alternative to plastic in many use cases.
The hemp fiber is strong and durable and is used in making yarn, twine, ropes, and cables. Moreover, the oil obtained from hemp plant is used to make paints, soaps, varnishes and edible oil as well.
The seed of hemp plants are rich in oil and is a source of protein, fibre and magnesium, making them beneficial for our overall health and wellness.
When the hurd of the hemp plant (which is the woody core found inside the stalk of the plant) is combined with lime and water, it forms hempcrete. Hemp possesses a high silica content that helps it to bind well with lime. It becomes a lightweight cementitious insulating material which weighs one-eighth to that of concrete.
Hemp, like other plants, absorbs carbon dioxide from the atmosphere during its growth stage, releases the oxygen, and retains the carbon. It has been estimated that a 35 cubic ft (1 cubic meter) hemp lime wall can absorb and lock 242 – 364 lbs (110 – 165 kg) of carbon during manufacture.
Being a low-density material and crack-resistant on movement, hemp lime is highly suitable for being used in the areas that are prone to earthquakes. Read more about the benefits of hempcrete.
How Old Is Hempcrete?
It is reported that the material was first developed in France during the 6th century, but in the 1990’s, it was used to construct non-weight bearing insulating infilled walls. Today, there are several construction companies in France using this technology; they have approximately made 200 to 300 homes so far. The use of hempcrete has expanded into other European countries (such as England) as well as into North America (notably The United States and Canada).
How Is Hempcrete Made?
It is made from mixing hemp hurds and lime. Usually, a lime binder is used to mix both the materials together. Both the materials are mixed for a few minutes before they are applied.
Being a fibrous and dry material, the hemp lime is cast around a steel, timber or concrete form. It does not require any expansion joints because the lime properties give hempcrete great flexibility and durability.
Learn more about the entire hempcrete making process.
How Long Does It Take To Dry?
It takes about 6 to 8 weeks to dry at around 12 to 15% moisture content before rendering with lime. A lot of care must be taken in order to keep the walls dry as a moist wall can lead to mold growth.
Additional Facts & Benefits
Foundation walls which are made from hempcrete are 7 times stronger and 3 times more elastic than those made by traditional concrete. Therefore, they can endure earthquakes.
It is waterproof, fireproof and 100% recyclable material which can also be used as a fertilizer once demolished.
Lime is a natural glue and also binds hempcrete. Moreover, lime is beneficial in making the hemp durable and preserves the natural fiber so that it lasts for generations. Hemp lime can also resist fire, mold, insects, and vermins.