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Hemp Slap Mix - An Alternate Sustainable Construction Binder made with Hemp

Today, human beings are opening up to preserve the world from the negative effects of unsustainable materials as well as the means of operations. One such domain affecting our climate today is construction and its rampant rise as one of the biggest industries have definitely highlighted it as one of the biggest polluters of the environment. There are many factors in the existing construction industry which make it unsustainable today. Apart from the use of unsustainable materials like cement and concrete to the need for transportation, the high level of carbon emissions is another reason making it mandatory for people to look for other alternatives while meeting our existing needs of building construction.

This need for alternative strategies have led to the emergence of a concept called “Zero-carbon Buildings” to boost micro generation of materials while adding renewable energy equipment with the building. Moreover, there is a need to consume less water while handling the operations in construction. There is another part of energy efficiency by increasing the insulation and many alternative materials including hemp provide what kind of thermal insulation is needed today for reducing the overall energy consumption. Therefore, one has to look into not just the methods of building but also, the materials being used in the construction industry for making a positive climate impact.

It only sounds foolish to use fossil-fuel based materials for manufacturing insulation when most of the governments and people in the world are trying to reduce the reliance on consuming fossil fuels. But as you look around in the market around you today especially in India, you will only find petrochemical-based products for producing energy. Most of these products are synthetic in nature and use highly toxic forms of additives like flame-retardants, binders and glues which directly cause environmental pollution. Brominated flame-retardants are biggest causes of pollution today. Since petrochemical-based materials are not easily biodegradable and lead to increasing problems with high deposits of these materials in the landfills.

But there is still a simmering hope after society started looking into more natural materials which are renewable with minimum fossil fuel energy consumption and minimal health risks as well as environmental pollution. In such times, crop materials like flax and hemp have become important as such alternatives. Himalayan Hemp Hurds when mixed sustainably with clay and cow dung as we used in the Hemp Slap Hut in Kullu, Himachal Pradesh, it leads to a green construction mix material which can be sustainably used in the process of construction. Hemp Slap Mix is essentially a carefully chosen material binder mix of Himalayan hemp shives or hurds, Himalayan Clay, and consistent dung of a cow heaving organic healthy diet. Hemp Slap Mix is high in hygric, thermal and mechanical properties with minimal ecological impact. We applied the mix in a wattle and daub arrangement which showed high level of flexural and compressive strengths. Using bamboo as a wattle helped in enhancing the load-bearing capacity of the structural material highlighting the possibility of creating high-rise construction buildings while establishing cradle-to-death greenhouse gas emissions, reusability and recyclability.

There is no denial in using some lime in the mix too for making it even stronger but we also understand the using lime as the only alternative only leads to the over consumption and illegal mining. Therefore, it is always better to have as many alternatives as possible to keep the sustainable prospects of the construction open to many others. Because we also know that even something good when overused can lead to severe ecological damage too.

We also used broken and waste hemp fibers in the Hemp Slap Mix because it increased the service life while reducing the structure’s life cost. It also has a positive impact on the social economy and social life because both farmers and construction workers were made a part of this project. Farmers can keep supplying the raw material as Himalayan Hemp Hurds and construction workers can stop working in hazardous conditions and can operate in safe work conditions. Himalayan Hemp plant can grow easily up to 7 meters in 7 months with low demand for irrigation and fertilisers making it quite efficient as a crop in terms of material resources as well as time and we take its fibers for making sanitary pads and use its hemp hurds in Hemp Slap Mix after breaking them down in a machine. Overall, including broken hemp fibers led to the increase in the coarse aggregate quantity without reducing the flexural performance of the hemp slap mix when used as a daub in the build.

Hemp Slap mix also provides exceptional hygrothermal properties meaning it can resist the heat and moisture when it is subjected to such environmental conditions. To test it more effectively, we built the Hemp Slap Hut in rainy season during the month of August. Our first workshop started on August 1, 2021 and concluded on August 25, 2021 while it heavily rained around us. Now, hemp hurds already exhibit hygric buffering and low thermal conductivity. Moreover, wattle and daub design helps in maintaining the air tightness with minimal thermal bridging leading to the making of a building envelope. All these aspects come together to create a low-carbon and highly hygrothermal building which are low energy not in just making during construction but also, during use once the build project is complete. Moreover, there are end use options in the terms of the recycling of the material at the end of its life. Today, the Hemp Slap Hut stands strongly in Kullu, Himachal Pradesh as India’s first experimental build project and it has opened doorways for many more experiments with our unique Hemp Slap Mix.

Himalayan Hemp is a community of farmers, artisans, innovators and now, eco-builders working on preserving the indigenous variety of Himalayan Hemp plants and marginalized communities of the Himalayas. Hemp Slap Workshop is our initiative to teach people about different methods as well as alternative materials to build their homes. Join us in the workshops that we keep conducting on a regular basis. You can always google Hemp Slap Workshop or check out our social media handles.


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