Hemp has several uses. It finds its application in up to 25,000 different products, including clothing, biofuel, and cosmetics. Hempcrete is the result of one such unique application. Infill walls that were not intended to support weight were initially constructed with hempcrete in France in the early 1990s. Hempcrete weighs just about an eighth of ordinary concrete and is manufactured by combining hemp hurd, lime, and water.
According to studies, Indians were aware of many of hemp’s beneficial characteristics in the sixth century. Both the Yadavas, who erected the Deogiri (Daulatabad) fort in the 12th century, and Ellora made considerable use of hemp. The Ajanta caves, a group of 30 Buddhist buildings carved out of rock dating to the second century BC, did not employ hemp. At least 25% of the paintings at Ajanta have suffered damage from frequent insect activity.
How is hempcrete produced?
The inner woody core of the stem of the hemp plant is combined with a lime-based binder to create the bio-composite known as hempcrete. Due to its high silica content, the hemp core, sometimes known as “Shiv,” binds to lime effectively. In all natural fibres, hemp is the only one with this characteristic. A lightweight cementitious insulating substance that weighs about a seventh or eighth of concrete is the end result. Blocks of finished hempcrete float in a bucket of water.
Why use hempcrete?
Hempcrete’s whole life cycle as a building material is environmentally friendly because it is created from a natural waste product, and this includes its eventual reuse or recycling in the case of destruction. Even growing hemp takes less water, fertiliser, and pesticides than growing other types of crops. In practically every region of the world, hemp is simple and quick to grow, and it yields two harvests year. It naturally inhibits the growth of weeds around it, reduces erosion, absorbs carbon dioxide as it grows, and also detoxifies the soil. Hemp is an attractive rotation crop for farmers due to the fact that what is left over after harvest decomposes into the soil, supplying essential nutrients.
The advantages of hemp remain once it is turned into hempcrete. The lime coat’s fire resistance is sufficient to allow occupants to flee in the event of a fire. Due to its localised nature and lack of smoke, it also lessens the risk of fire spread and smoke inhalation. Hempcrete is vapor-permeable and won’t lead to any skin or respiratory issues, resulting in a healthy interior atmosphere. Its lightweight construction and the air pockets generated among the particles imply hempcrete is both earthquake-resistant and an efficient thermal insulator.
By minimising the emissions caused by moving heavy materials, hempcrete’s small weight can help lower a building’s embodied energy. Industrial hemp is a great substitute for local building materials since it can be grown in a variety of soils and climates. Construction waste reduction is another significant issue that hempcrete can help with. While structural parts of a structure cannot be made of hempcrete, non-structural parts of walls that would typically be made of concrete can be. Hempcrete can also be used in place of typical building supplies like plaster and drywall, which make up around 8% of construction waste.
In a recent article for the Journal of Cleaner Production, S.R. Karade, senior principal scientist at the Central Building Research Institute in Roorkee, India, outside of New Delhi, discussed the performance of hempcrete as a building material in terms of insulation, durability, structural strength, and acoustic control, among other factors. Overall, according to Karade, hempcrete satisfies the requirements for the majority of building applications and frequently performs better than the materials currently in use, especially for insulation.
The strength of hempcrete
Since hempcrete’s compressive strength is just 1/20 that of concrete, or 1 MPa, it cannot be utilised as a foundation material or in other circumstances where it might be load-bearing. Because of its low density and resistance to cracking, it makes a good choice for earthquake-prone areas. Termites avoid hempcrete because it breathes, does not off-gas, and allows moisture to evaporate (preventing mould). Hempcrete is non-toxic and lightweight, making it simple to move about a job site. Even while hempcrete is becoming more and more popular, it is still not generally accessible. However, the price of hempcrete is equivalent to that of other insulation solutions, and it will get cheaper as manufacturing volumes rise.
Alternative Applications of Hempcrete
Both prefabricated external wall panels and structural blocks can be made from hemp. These exterior wall solutions, as opposed to normal bricks or cinder blocks, raise the R-value by integrating thermal performance into the structural part of your home as well. If hempcrete isn’t exposed to an excessive amount of moisture or water, it is a great insulation alternative for subfloors, walls, and attics. The common usage of hemp plaster is another. It combines the attractive appearance of traditional stucco with the advantages of sealing and rain protection. Hemp has recently been utilised to make countertops and cabinetry.
Hempcrete in India
India’s hemp sector is a prerequisite for the production and marketing of hempcrete. Although the Indian state of Uttarakhand has legalised hemp growing for industrial use, we do not currently have the cultivars of hemp that meet the requirements of the state’s hemp policy, which call for THC levels of below 0.3% It goes without saying that importing seeds from other countries is expensive and not a viable company. This has an impact on the manufacturing of the hemp shivs needed to manufacture hempcrete. One hectare of hemp farming is required to supply the food for a 1000 square foot hempcrete house.
A type of vegetative concrete known as hempcrete is being actively produced and used in nations including England, France, and Belgium. For the production and use of products like hempcrete, their authorities have developed certification and authorization procedures. Such products are not widely used in India, and public organisations have not stepped up to support or acknowledge them.