Hemp and Lime

    Hemp-Lime is a composite construction material that can be used for walls, insulation of roofs and floors and as part of timber-framed buildings. It provides very good thermal and acoustic performance, and offers a genuinely zero-carbon contribution to sustainable construction. Hemp masonry is breathable and is able to absorb and emit moisture, leading to much healthier buildings.
During our Summer 09 course we had a discussion related to pros and cons of using lime and its carbon footprint. We decided to experiment with this composite, as we concluded that advantages are greater than disadvantages.  We were aware of its limited use within Bulgaria so thought it would be nice to spread the word a bit and gather some interest ,especially given the widespread availability of both of these materials within Bulgaria . The hemp part of the composite is actually just the husk of the Cannabis Sativa plant which is dried and broken down into small pieces. The product is then marketed  ready to mix with lime. Unfortunately we could not find anywhere in Bulgaria that sold this material and searches further afield were not  fruitful. We did have an option to take a 200KG uncut  bale of hemp from Northern Romania,  but the logistics of getting it to us were troublesome to say the least and fortunately whilst musing over our dilema,  we chanced upon a field of wild growing specimens ripe for the pluck and better still it was just a km or two from our newly acquired land! Manna some may say, it certainly felt like divine intervention.
Freshly picked Hemp, ahhhhh what a smell
40 minutes later with a car packed full of the herbs our silent prayers were answered again when we arrived home without being pulled over by the Traffic Police. As innocent as our reason to have  a car full of cannabis were  i'm not sure how well it would have been received by the local sergeant. It was very exciting to find this amazing plant growing locally and made the pending demonstration more relevant. In principal we could grow enough hemp on the land  to build a house but first the small quantity we had  would need to be cut up into small pieces ready for the lime mix. Without machinery this is very labourous and tedious work but luckily there were many hands on the job and we soon had enough hemp material for our humble demonstration. 
The White Lime was purchased from a local store in 10Kg bags for  2.20BGN per bag 
The dry small pieces of Hemp husk was  showered with water and 3 parts Hemp 1 part Lime was mixed together  
The mix was poured into a purpose built form and compressed, the form represents a wall.
After a short while our mock wall infill was full and dry enough to remove the front planks


Presto you have a super insulative wall ,although this was a small scale demonstration the speed of which you can work with this composite is amazing. With hemp growing so well in this climate and lime being  relatively cheap we see a very attractive  option to build larger structures .All in good time.

 As an impromptu experiment  we also tried mixing the lime  with other plant material i.e  pruning's from this springs fruit trees  and Elderberry branches cut in to small pieces with the bark removed. The idea was to see how well it may perform as a substitute for hemp. The blocks we made dried well and will be tested for there insulative properties at a later date.  
Further Reading
A blog devoted entirely to hemp and lime
How good is Hemp and Lime?
Other usage of Hemp and lime