International Journal of Research and Innovation in Applied Science (IJRIAS) |Volume VIII, Issue III, March 2023|ISSN 2454-6194

Industrial Cannabis sativa (Hemp fiber): Hempcrete-A Plant Based and Eco-friendly Building Construction Material

Ravindra B. Malabadi*1, Kiran P. Kolkar2, Raju K. Chalannavar1
1* Department of Applied Botany, Mangalore University, Mangalagangotri-574199, Mangalore, Karnataka State, India
2Department of Botany, Karnatak Science College, Dharwad-580003, Karnataka State, India
*Corresponding author

Abstract:- This review paper highlights about the Industrial hemp (fiber type) used as a plant based building construction material, Hempcrete. Industrial hemp (Cannabis sativa L.) is an emerging food and fibre crop. It is a non-drug variety of Cannabis sativa with low Δ9-tetrahydrocannabinol (THC) content of less than 0.3 per cent. The use and performance of hempcrete suggested that hempcrete can be considered as an environmentally friendly material. In a first of its kind in India, an architect couple, Namrata Kandwal and Gaurav Dixit have built a house made of using hemp fibre- hempcrete in Uttarakhand state, India. Industrial Hemp (fiber-type) is both an agricultural and industrial commodity and stem supplies both cellulosic and woody fibers. Hempcrete is a construction material made from hemp fibres, lime and water. Hemprete showed a negative carbon footprint making it a suitable material in the construction industry. This composite, hempcrete breathes, as well as having a good thermal and acoustic-insulation properties. However, hempcrete does have several key drawbacks that make it less than ideal as a building material. In addition to poor mechanical performance, hempcrete also has a high capacity to absorb and retain water. Therefore, future in detail study is warranted for the commercialization of hempcrete as a building material.

Key words: Cannabis sativa, hemp, Hempcrete, Industrial hemp (fiber type), bio-based composite, Eco-friendly, sustainability, carbon neutral, affordable home construction, Uttarakhand state, India.

I. Introduction

Industrial hemp (fiber type) belongs to the family, Cannabaceae is considered as one of the oldest plants cultivated to provide the nutritional and medicinal benefits (1-30). Industrial hemp (fiber type) is a versatile commercial crop that has been used for fiber, food, and medicinal purposes (1-50, 60). Further planting Industrial hemp (fiber type) has numerous advantages that makes it easy to work (1-40). The Industrial hemp (fiber type) plant becomes ready to harvest 100 to 120 days after it has been planted (1-55). Industrial hemp (fiber type) does not need much caring, weeding, or cultivation, and hemp can grow on new or old soil (1-63). Hemp plant can withstand extreme temperatures like frost and only requires modest amounts of water (1-63). Moreover, harvesting Industrial hemp (fiber type) can be more favourable for the use of land (1-50). Hemp not only allows the soil to be used for other crops after harvesting, compared to growing trees (1-23, 28-62). Hemp also reduces logging and soil erosion drastically, and thus decreases topsoil loss and soil runoffs that may cause pollution in water (1-55). Hence one of the most promising material for building construction is hemp fiber (Cannabis Sativa L.) (1-60). Hemp is both an agricultural and industrial commodity, highlighted by its usefulness as a sustainable resource (1-50). In addition, hemp has the ability to absorb carbon dioxide while it is being grown (1-50). However, as it more specifically relates to the field of civil engineering, hemp can be mixed with lime to form a bio-aggregate concrete, known as “Hempcrete” (1-62).

Hempcrete is a lightweight concrete, made from hemp pulp (or shiv), and hydraulic or aerated lime (1-50). It is typically used for timber frame infill, roofing tiles, insulation, renders, and floor slabs (1-21). Although hempcrete cannot provide enough structural integrity to be used as a load-bearing material (1-59). In the construction phase, hempcrete is the most commonly used for a timber frame infill, which is built using a removable formwork mold, such as a plastic casing (1-59). The most complicated process of the mixture design is getting the correct ratio between the fluid phases, air, water, the solid phases, hemp shiv and the binder (1-50). For instance, an example of a walling application would include 100 liters of hemp shiv, 22 kg of Tradical ® PF70 lime, and 30-35 kg of water (1-50).

Hempcrete is a highly breathable material, which allows for the regulation of indoor temperature and humidity (1-45). This is mainly caused by the porosity of hempcrete, which allows the transfer of water vapour with the surrounding air (1-50). This phenomenon occurs at times of high humidity, allowing the vapour to condense back into the liquid state and coming to rest on the surface of the pores (1-21). This process can be reversed in times of low humidity, essentially acting as a natural humidifier (1-45). Consequently, this has an interesting effect on the thermal conductivity of hempcrete (21). Hempcrete locks

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