Hempcrete/hemplime is a bio-composite made of the inner woody core of the hemp plant Cannabis Sativa L. mixed with a lime-based binder. The hemp core or “Shiv” has a high silica content which allows it to bind well with lime. This property is unique to hemp among all natural fibers. The result is a lightweight insulating material ideal for most climates as it combines insulation and thermal mass.
Like other plant products, hemp absorbs CO2 from the atmosphere as it grows. Furthermore the carbonization lime during curing adds up to this effect as lime turns to limestone, a process that may last 100 years. Hempcrete is a renewable, non-toxic and breathable material that produces a comfortable and healthy indoor living environment with high indoor quality. It is a low density material (around 1/7th the weight of concrete) and resistant to crack under movement thus making it highly suitable for use in earthquake prone areas.
The concrete industry is responsible for a large amount of CO2 emissions worldwide. Global CO2 emissions from cement production represent 4.5% of global CO2 releases from fossil-fuel burning. Other disadvantages include phenomena such as surface runoff, the urban heat island effect, generation of concrete dust and emission of toxic and radioactive substances. These hazards only make the need for more ecological and human friendly construction greater.
Hemplime is one of the best performing, non-toxic, ecological and renewable materials available. It has a negative CO2 footprint thus alleviating the Greenhouse effect. It improves air quality, energy consumption for heating and cooling providing a comfortable and healthy living environment. Cool in summer and warm in winter.
|λ Value (W/mK)|| 0.06-0.09
|U Value 300mm wall thickness||0,23|
|Fire resistance|| ~1 hr / 10 cm wall
|CO2 Enchain||110-165 kg/1 ton|
|Hygroscopicity||3.4 x 10-5 PSI|
- Durable (weather-resistant).
- Solid mass construction giving good air tightness (no heat or cool lost through air gaps).
- Hygroscopic thereby buffering fluctuating temperature and humidity.
- Negative carbon footprint (~100kg of CO2 lockup per cubic meter used).
- Fully recyclable and reusable without huge energy requirements to break it down.
Hempclay is a new insulative building material that consists from of the inner woody core of the hemp plant Cannabis Sativa L. mixed with clay binder. The success of the mixture is based on the purity and quality of clay and hemp hurds.
The natural binders are colloids, of which clay is the most common and oldest in use during the human construction history. Clay is considered to be the material in the soil, smaller than 0.002 mm.
It is sticky and swells when wet, hard and shrinks when dry. Clay particles are in the form of round or polygonal flat discs/plates. They have an electric charge that makes them to operate like magnets. When dry, all the negatively charged sides cling to positively charged sides of another clay disk next to them. The addition of water separates the discs far enough apart to weaken the electric charge. When the water evaporates, the electric charge is re-activated, binding the clay disks back together. Therefore clay is in a constant and reversible state of flux.
Due to the nature of clay, Hempclay is proposed for dry climatic zones or inner walls. Hempclay requires more drying time, but includes less energy production than Hemplime.
Hemplime & Hempclay are the new allies, along with other natural materials like straw, clay, wood and stone, in constructing buildings that last for generation, reinventing the meaning of ‘Eco-Construction’ (Ecodomè in Ancient Greek translates to "House Construction").
- James Henderson: Earth Render - The Art of Clay Plaster, Renders and Paints
- Gernot Minke: Earth Construction Handbook - The Building Material Earth in Modern Architecture
- American Lime Technology
- Hempcrete Australia PTY LTD. Energy saving eco building
- NRMCA Publication Number 2PCO2 Concrete CO2 Fact Sheet February 2012
- Hemp Materials