Hempcrete is a mixture of hemp

Hemp

Hemp is mostly used as a name for low tetrahydrocannabinol strains of the plant Cannabis sativa, of fiber and/or oilseed varieties. In modern times, hemp has been used for industrial purposes including paper, textiles, biodegradable plastics, construction, health food and fuel with modest...

 hurds (shives) and lime (possibly including natural hydraulic lime

Hydraulic lime

Hydraulic lime is a variety of lime, a slaked lime used to make lime mortar. Hydraulicity is the ability of lime to set under water. Hydraulic lime is produced by heating calcining limestone that contains clay and other impurities. Calcium reacts in the kiln with the clay minerals to produce...

,sand

Sand

Sand is a naturally occurring granular material composed of finely divided rock and mineral particles.The composition of sand is highly variable, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal...

, pozzolan

Pozzolan

A pozzolan is a material which, when combined with calcium hydroxide, exhibits cementitious properties. Pozzolans are commonly used as an addition to Portland cement concrete mixtures to increase the long-term strength and other material properties of Portland cement concrete, and in some cases...

s or cement

Portland cement

Portland cement is the most common type of cement in general use around the world because it is a basic ingredient of concrete, mortar, stucco and most non-specialty grout...

) used as a material for construction and insulation

Building insulation

building insulation refers broadly to any object in a building used as insulation for any purpose. While the majority of insulation in buildings is for thermal purposes, the term also applies to acoustic insulation, fire insulation, and impact insulation...

.
It is marketed under names like Hemcrete, Canobiote, Canosmose, and Isochanvre.
Hempcrete is easier to work than traditional lime mixes and acts as an insulator and moisture regulator. It lacks the brittleness of cement and consequently does not need expansion joint

Expansion joint

An expansion joint or movement joint is an assembly designed to safely absorb the heat-induced expansion and contraction of various construction materials, to absorb vibration, to hold certain parts together, or to allow movement due to ground settlement or earthquakes...

s.

However, the typical compressive strength

Compressive strength

Compressive strength is the capacity of a material or structure to withstand axially directed pushing forces. When the limit of compressive strength is reached, materials are crushed. Concrete can be made to have high compressive strength, e.g...

 is around 1 MPa, over 20× lower than low grade concrete

Concrete

Concrete is a composite construction material, composed of cement and other cementitious materials such as fly ash and slag cement, aggregate , water and chemical admixtures.The word concrete comes from the Latin word...

. Hempcrete walls must be used together with a frame of another material that supports the vertical load in building construction.
Hempcrete's density is 15% of traditional concrete, as well as carbon negative

Carbon negative

Carbon negative is an adjectival phrase used to describe any process that removes carbon dioxide from the atmosphere, with the intent to avoid global warming.-Carbon dioxide sinks and carbon negativity:...

.Like other plant products, the hemp crop absorbs CO₂ gas as it grows, retaining the carbon and releasing the oxygen. 165kg of carbon can be theoretically absorbed and locked up by 1m³ of hempcrete wall over many decades.

External links

• Hemcrete application data from Limetechnology