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Hempcrete or Hemplime is bio-composite material, a mixture of hemp hurds (shives) and lime (possibly including natural hydraulic lime, sand, pozzolans) used as a material for construction and 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. Hempcrete has been used in France since the early 1990’s to construct non-weight bearing insulating infill walls, as hempcrete does not have the requisite strength for constructing foundation and is instead supported by the frame. France continues to be an avid user of hempcrete; it is growing in popularity annually. A typical brick house can be responsible for 50 tonnes of CO2 emissions in its construction however, it is claimed that the same house can be built for 40% less CO2 by using Tradical Hemcrete. This is because 110kg of CO2 equivalent is captured in every cubic metre of Tradical Hemcrete wall mix, making it carbon negative. It also has a very low energy cost in use, is recyclable and is produced in the UK. Tradical Hemcrete was developed by U.K.-based Lhoist Group. It is composed of a lime based binder and the inner woody core of a hemp plant. The materials are mixed with water and sprayed. It can then be used for the construction of walls, in the renovation of old buildings, to form in-fill panels for historic timber frames, or as an insulating plaster or render system for the thermal upgrading of masonry buildings. Family homes have been constructed that include enough Tradical Hemcrete for them to achieve level 4 in the Code for Sustainable Homes. Level 4 means that the house’s emissions are 25% lower than ‘normal’. The thickness of Tradical Hemcrete has so far been limited to 450mm due to difficulties with drying times, and even at those thicknesses, drying times can be more than 4 weeks. This drying issue can impact on the sustainable credentials of the product as large industrial fans are sometimes used to dry panels.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.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 cracking 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. |
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Hemcrete Wall Structure – Tradical Hemcrete is a bio-composite building material made from hemp shiv (the woody core of industrial hemp) and a lime based binder called Tradical HB. Recent research has shown that the dynamic performance of Tradical Hemcrete is even better than previously thought once it is fully dry. However, the drying of Tradical Hemcrete is dependent on job site weather conditions.Tradical Hemcrete has the following properties:
Tradical Hemcrete is normally used to create the walls of new buildings, but can also be used in the refurbishment of existing buildings. Tradical Hemcrete has a unique combination of insulation and thermal inertia and these properties combine to create building with very stable internal environments that need very little heating or cooling (if appropriately designed and constructed). |
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