HEMPCRETE

BUILDING WITH HEMP

When hemp hurd (the woody core of the stem) is mixed with a lime binder and water it petrified into a biocompsite substitute commonly known as Hempcrete. Hempcrete is lightweight cementitious insulating material weighing about a seventh or an eighth of the weight of concrete. Fully cured hempcrete blocks float in a bucket of water

Hempcrete has significant advantages over concrete. It is breathable, fire resistant and a good insulator, and can be used as a fill around a timber frame, as a finishing plaster, or to build freestanding walls.The Hemp plant absorbs atmospheric CO2 during the plantgrowth phase, and again as the material gains strength andmatures. (100sq m with 300mm thick walls) will lock up 7.9 tonsof CO2 in the walls. Estimated rate of carbon sequestration is165Kg CO2 capture/m2. Therefore, building with Hempcrete reduces atmospheric CO2

EXCELLENT THERMAL INSULATION CHARACTERISTICS

Insulation

Hemp houses show superior thermal properties to the conventional homes: the exterior walls of the conventional homes were 4-6°C warmer than those of the hemp houses, indicating that loss of heat through the conventional brick walls was considerably greater than that through the “Hempcrete’ walls

Excellent Thermal

Tests of the thermal conductivity of walls by Plymouth University led to an agreed reading of 0.08w/mK. These were taken on a 200mm thick wall that had been constructed a number of years earlier. The “R” value (thermal resistance) is 2.75 with plaster and surface resistances taken into account. “U” value (rate of heat loss or gain) derived from this would be in the region of 0.36 -0.37W/m2K. This empirical work confirmed a lambda value of 0.08 – 0.09 for hemp and lime and as this conservative figure has been confirmed by so many authorities that it seems to accept this when making building regulation applications. (Bevan and Woolley, 2008)

Hempcrete regulates the temperature and humidity of a building; in some cases completely eliminating the need for heating and cooling systems, resulting in huge energy savings. Hempcrete is carbon negative and the obvious choice for buildings aiming to achieve a low carbon footprint and the highest sustainable building code levels.

Excellent Acoustic Isolation

Hempcrete has very good acoustic components due to its open structure. Hempcrete has a low propagation rate, a figure of ~900Vson m/s against steel with ~6110 Vson m/s. Hemp concrete is characterised by its high porosity that combines the microscopic pores of its binder and its vegetable particles, and bigger pores between the particles. Thus, its sound absorption is intermediate between the excellent absorption of hemp shiv, and the reflexion of the binder.

Fire Retardant, Termite & Rodent Resistant

Fire tests on a 300mm thick Hempcrete wall gave 73 minutes, for structural adequacy/integrity/insulative capacity.   Based on the reported performance under full-scale fire exposure and the similarity of exposure and performance criteria between AS 1530.4-2005 and BS EN 1365-1:1999, Tradical® Hempcrete Wall System as reported in BRE Test Report number 250990, would be capable of achieving an FRL of 73/73/73, if tested in accordance with AS 1530.4-2005.

OzHemp Tradical® Hempcrete is CodeMark certified -BAL FZ (Achieved in compliance with FRL) suitable for use in all bushfire prone areas (Low to Flame Zone).

John French, a leading Queensland and international entomologist, has tested Hempcrete in the Northern Territory and Queensland found termite have no effect on the Hempcrete samples.

HEMPCRETE OVERVIEW

The material is mixed in mortar mixers for 1-2 minutes and stuffed by hand into the wall cavities. The wall is slip-formed with temporary wooden or plastic “shuttering” forming the inner/outer surface forms. The material is lightweight and can be moved easily about the site in tubs and passed up bucket-brigade fashion to workers filling the cavities. Site clean-up is easy. Simply till it into the soil The material is finished on the outside with a hard render coating about 20mm thick to protect it with a final colored topcoat finish added. The end result appears like any stucco finished building. The inside can be left natural or finished with lime plaster for a traditional look.

The material is finished on the outside with a hard render coating about 20mm thick to protect it with a final colored topcoat finish added. The end result appears like any stucco finished building. The inside can be left natural or finished with lime plaster for a traditional look.

Hempcrete was discovered in a bridge abutment in France built in the 6th century. Since its rediscovery it has seen growing use in Europe. Industrial hemp is grown by certified commercial growers so the crop can be certified to be very low in THC. Hemp is not psychoactive. Given it has survived 14 centuries, people expect Hempcrete buildings will have a long life.

Residential construction is responsible for producing 23.8 megatonnes of carbon dioxide (CO2) annually. The manufacturing of synthetic insulation materials contributes enormously to their high embodied energy and the overall CO2 equation.

Hempcrete buildings act as a carbon sink, preventing the release of CO2 back into the atmosphere. An average size house constructed of hempcrete will remove about 20 tonnes of CO2 from the atmosphere over its lifetime. This makes hempcrete construction a negative carbon emitter because of its ability to lock up more CO2 in the building than is emitted during its production, processing and transportation.

Lime absorbs CO2 during its carbonation process which helps to reduce the CO2 in the air. It’s a highly breathable material with natural anti-bacterial and insect-repellent properties and is considered carbon neutral.

One hectare of industrial hemp can absorb 15 tonnes of CO2 per hectare. Hemp’s rapid growth makes it one of the fastest CO2-to-biomass conversion tools available, more efficient than agro- forestry.

INTRODUCTION TO TRADICAL®

Tradical® construction materials are developed products of the Lhoist Group based on high purity manufactured lime materials. The Lhoist Group is an international business focused on the supply of high purity lime products to many industries including the construction industry.

OzHemp Pty Ltd is currently the only supplier of BCA (Building Codes of Australia) certified hempcrete products and installation methods in Australia and New Zealand, according to The Australian Building Codes Board (ABCB).

The Australian Building Codes Board (ABCB) and The Joint Accreditation System of Australia and New Zealand (JAS-ANZ) have approved the use of Ozhemp Tradical® Hempcrete and its methods to the housing and commercial construction industry.

Tradical® Hempcrete is a unique, highly sustainable construction product for the creation of insulating walls as well as insulation layers for roofs. Tradical® Hempcrete is a blend of specially prepared hemp shiv and a special lime based binder Tradical® PF70. Together these products form a bio-composite building material that can be used both for the creation of buildings that have excellent thermal and acoustic properties as well as creating a healthy living and working environment.

Additionally, Tradical® Hempcrete has the ability to make an impact on the future of sustainable building. Helping to reverse the damaging effects of greenhouse gases, Tradical® Hempcrete locks up approximately 110kg of CO2 per m3 of wall and provides one of the best value materials for low impact, sustainable and commercially viable construction.

Produced mainly from renewable sources, Tradical® Hempcrete is mixed on site for fast track construction and delivers high levels of insulation, air-tightness and vapour permeability.

PROPERTIES

  • Low density
  • High thermal insulation
  • High sound insulation
  • High thermal inertia
  • Good vapour permeability
  • Good flexibility
  • Fire and pest resistant
  • Can significantly reduce CO2 emissions
  • Inherently air-tight structures
  • Low waste

Benefits And Capabilities

Combining patented formulations of air-lime based binders with the chopped core of the industrial hemp plant stem, delivers a suite of new building products. These Tradical® Hemp Lime products have excellent performance characteristics for durable, healthy, sustainable and ecologically sound buildings.

Tradical® Hemp Lime products deliver excellent application, durability and aesthetic performance characteristics combined with sustainability, economic, comfort and health qualities that architects, developers, contractors and customers will value.

  • Design
  • Application
  • Durability
  • Aesthetics
  • Sustainability
  • Economic
  • Comfort & Health
  • Carbon Balance

Tradical® Products

Tradical® PF: these ready-to-use pre-formulated binders combine air lime and hydraulic binders so that you get the best of both for your projects. To be used in brickwork and blockwork, rendering & plastering

Tradical® PF is a product line of different air lime-based pre-formulated binders to meet all needs in terms of building masonry, rendering and plastering in the renovation and new build market segments.

Tradical® PF incorporates in one mixed product all necessary ingredients to make high-quality/high performance air lime mortars compatible with all kinds of wall structures.

Tradical® PF brings all the necessary performances for a successful masonry work:

Technical performance:

  • Elasticity
  • Application-specific compressive strength
  • Vapor permeability
  • Durability

Value performance:

  • Workability
  • High-yield product
  • Lower maintenance masonry

Environmental Performance:

  • Low energy/high-carbon capture masonry
  • Solvent-free
  • Sustainable masonry
Note: Please note that cementitious or hydraulic binders that have not been designed to be used with hemp may produce unacceptable results. The failure is often related to the competition for water between the binder and the hemp. If the binder has insufficient moisture for the hydraulic components to set, then the result can be a mixture of damp hemp and/or dry powder.
By adding sand to the mixture will make the product denser, thereby compromising its performance characteristics; reduction of thermal rating, breathability and restricted movements. This high-density wall with restricted movements will result in cracks. Hempcrete or Hemp-Lime bio-composite is a lightweight insulating material. By adding sand, the product has become dense hemp masonry and not hempcrete.
The present of cement and sand will prevent hempcrete from “breathing”. Hempcrete walls need to “breathe” to ensure there is interaction with both the internal and external environment – this allows for the Hempcrete to absorb/desorb water vapour (humidity) as well as the ability to buffer temperature fluctuations.
Tradical® Hempcrete only uses Tradical® lime binder, building grade hemp hurd and water, combined in appropriate proportions. The resulting mixture becomes a bio-composite lightweight substitute commonly known as Tradical® Hempcrete. We don’t recommend the use of sand due to the additional weight, loss of insulation and loss of breathability integrity.
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