Hempcrete or Hemplime is a composite building material, a mixture of the chopped woody stem of the hemp plant known as hemp hurds (shives) and a lime based binder to create a material that can be cast into molds. This forms a non-load-bearing 'breathable' insulating material that can be used to form walls, floor slabs, ceilings and roof insulation. It is marketed under names like Hempcrete, Canobiote, Canosmose, and Isochanvre. Hempcrete is easier to work with than traditional lime mixes and acts as an insulator and moisture regulator. It lacks the brittleness of concrete and consequently does not need expansion joints. 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, retaining the carbon and releasing the oxygen. Theoretically 165 kg of carbon can be absorbed and locked up by 1 m3 of hempcrete wall during manufacture. Furthermore, the carbonation of the lime during curing adds to this effect as lime turns to limestone. The typical compressive strength is around 1 MPa, around 1/20 that of residential grade concrete. It is a low density material and resistant to crack under movement thus making it highly suitable for use in earthquake-prone areas. Hempcrete walls must be used together with a frame of another material that supports the vertical load in building construction, as hempcrete's density is 15% that of traditional concrete. Rammed earth Rammed earth is a wall system made of compacted earth, or another material that is compacted. It is extremely strong and durable. Quality rammed earth walls are dense, solid, and stone-like with great environmental benefits and superior low maintenance characteristics. As an option depending on climate rigid insulation can be placed inside the wall. Similarly, depending on seismic concerns bamboo or other tensile natural materials can be used to reinforce the wall. Rammed earth has been used for around 10,000 years in all types of buildings from low rise to high-rise and from small huts to palaces. Rammed earth walls are formed in place by pounding damp sub-soil (containing sand, clay and sometimes gravel) into movable, reusable forms with manual or machine-powered tampers. In traditional rammed earth, a mixture of around 70% aggregate (gravel, sand) and 30% clay is optimal. Pigmentation may be added in the mix to achieve the desired color. Around 5-10 inches of mixed