Hemp and Lime
The choice of a biocomposite based on hemp and lime is the result of a research work aimed at achieving a desired goal: the regeneration of the entire system and at the same time the establishment of a new business model, which would offer huge advantages under the social and environmental aspect.
Hemp is a raw material that, if available on a large scale in Italy, would make the fortune of many sectors : agriculture, industry, pharmaceuticals, food, manufacturing, construction and service sector. Excellent for all uses in terms of quality, but a problem remains… the lack of knowledge, availability and the artisanal approach of the main players in Italy before 2010, made it uncompetitive in all sectors except one: Construction.
The mixture of hemp and lime offers a totally natural product, capable of respecting the environment, solving the problems of current buildings and giving high comfort and wellbeing to the inhabitants. Hemp solves the current and widespread problems in the construction sector: the sick building syndrome, the limited comfort and living wellbeing, and the particularly ever-increasing number of energy consuming buildings. All this without alternative materials capable of giving the same results.
Thanks to the experimentation in Italy of French and English technology, and to research and development, we have managed to break down the barriers that for years have limited the use of hemp on a large scale in the construction sector, with technological innovations that allow you to build walls for passive houses at the same cost of traditional systems, often energy-consuming and ineffective. Until now, we use all the hemp available in Italy and we import just as much from France… this allows various companies in Italy to invest in the supply chain, and to expand the coils of the virtuous circle imagined and created at the beginning of this project.
What is Hemp ? (Cannabis Sativa L.)
Hemp Sativa is an annual cycle herbaceous plant with a thin stem that varies in height from 1.5 to 4.5m and a diameter from 0.5 to 2.0 cm.
The stem is composed of an external surface, containing long and very resistant fibres, and an internal woody core, also called ‘hemp shiv’. It can be more or less branched depending on the density with which the plants are sown. When sowed tightly, the stems do not branch out at all.
Hemp and marijuana are not the same. The THC content of industrial (legal) hemp is 0.2% or less. The THC content of (illegal) marijuana can range from 5 to 20%.
A bit of history…
Hemp was already cultivated by the Chinese 8,500 years ago and was exploited mainly as a source of fibre and only to a limited extent as a source of oil seeds. Hemp use for fibre first spread to western Asia and Egypt and then to Europe between 1000 and 2000 BC. Its cultivation in Europe became extensive after 500 AD.
Since the beginning of the 20th century, hemp fibre was of perfect for the production of ropes and was described as “the queen of fibre plants, the standard by which to compare all other fibres”.
The Marijuana Tax Act of 1938 effectively ended the cultivation and processing of hemp in the United States; prohibition that subsequently spread in Europe and practically all over the world.
The diversity of products for which hemp can be grown is extraordinary. The well-known American magazine Popular Mechanics celebrated the plant as “the million-dollar crop”, stating that “it can be used to make more than 25,000 products, from dynamite to cellophane”.
Hemp is an extremely resistant plant, which can grow at virtually any latitude without the use of fertilisers and pesticides. During its life cycle it sequesters large quantities of carbon, due to its very fast growth (on average 120 days). The biomass yield is also particularly high: during the growth cycle, if mechanically defoliated, most of the biomass returns to the soil and decomposes quickly. It also has a land reclamation effect because it absorbs pollutants such as zinc and mercury. Finally, during harvesting, the roots are left on the ground, keeping the soil compact and functioning as an aeration duct for the subsoil
» Bio-plastic products
» High-quality paper
» Insulating panels for building
» Biodegradable geotextile materials and gardening products
» Raw textile products (carpets, upholstery)
» Delicate textile products
» Construction: Building (biocomposite of hemp and lime, panels, plasters)
» Construction: thermal and acoustic insulation
» Animal litter
» Pastry, bakery products
» Seasoning oil
» Cosmetics for body care
» Animal feed (whole seed for birds, squeezing waste for fodder)
» Food supplements of gamma-linolenic acid
» Special oils for industrial use
» Fuel (biomass and biofuel)
The advantages for building
Hemp shiv is composed of microscopic alveoli filled with air in which alternate, continuously, processes of micro-condensation and micro-evaporation. This configuration allows to block the passage of heat and cold from the outside to the inside of the building (and vice versa) and to regulate humidity, offering exceptional living comfort.
- Thermal insulation
- Thermal mass
- Humidity regulation
Lime can be classified, according to the way it hardens, into:
Air lime: through the slow combination with carbon dioxide in the air (carbonation process)
Hydraulic lime: through the combination of water with silicates and aluminates (impurities naturally contained or added later)
A bit of history…
Lime is a material used in construction since ancient times.
The Egyptians used it to plaster the pyramids about 6000 years ago, the Romans regularly used lime-based mortars (Pantheon, waters, etc.)
The use of lime as a binder was really common until the 19th century, when the invention of Portland cement subsequently led to its decline.
In the last 20-30 years, there has been a return of lime in the conservation work of historic buildings due to the damage resulting from the use of cement.
Advantages of Lime in Construction
Breathability: direct consequence of its high porosity and vapour permeability
Self-repair: building with lime, the cracks caused by the contraction and expansion are limited: the moisture that penetrates allows the dissolution of the ‘free’ limestone that settles and repairs them.
Thermal conductivity: helps to increase the feeling of comfort in both hot and cold climates.
Workability: ability of a mortar or plaster to remain homogeneous and mouldable. Consequence of the plasticity and water retention of lime.
Durability: when used properly, lime is extremely durable.