I’ve done a lot of research on this including visiting hemp farmers. I’ve seen, held and tested samples of different hemp manufacturing techniques such as ‘hemp paper’, ‘hemp board’, ‘hemp fibreglass’ and ‘hemp plastic’ created by extruding hemp cellulose or using fibres, often in combination with other materials.
Having seen the flexibility of hemp as a raw material I have an issue with people confusing the virtues of a single product like ‘hemcrete’ with the hemp industry as a whole. Ultimately the properties of one manufacturing technique says very little about the usability of hemp in construction. It is entirely possible to create stronger materials than concrete out of, or in combination with hemp. Again I have seen these materials.
There is a scientific basis behind hemps strength. Firstly hemp is approximately 70% cellulose – which is natures glue and the basis of plastic. Secondly it has long, very strong fibres which form the basis of reinforcement in fibreglass and many building materials. It isn’t the only plant with these properties but it is generally easy to grow, requires few chemicals and is capable of being selectively bred to enhance desirable properties.
Which brings us back to why it isn’t used. When hemp was banned it was entirely due to DuPont Chemical manipulating the US treasury. It was done to protect his interests in cotton, synthetic fibres (hemp was banned in 1938, the same year nylon was patented) and timber interests. The simple truth is powerful lobbies for timber and chemical industries have conspired to keep it out of the public’s reach ever since. Big business fears nothing more than regulation and competition and hemp is competition. It will never become legal in America as long as these lobbies have such power.
I can’t even enumerate all of the problems with this. But. here is a small list:
1. Cellulose aggregate concrete(Hemcrete) is NOWHERE near 7 times stronger than stone and sand aggregate concrete. Their claim is a flat out lie! In fact, their website states that the compressive strength is so low that it can’t be used fro load baring applications.
2. Doesn’t rot is an exaggeration that may be arguable. But, the mold problems with cellulose construction is a very real issue.
3. Insects, specifically termites are a real issue despite the manufacturer’s claims.
Cellulose reinforced construction is nothing new. It was used in ancient Egypt and in the Great Wall of China. But, as time and technology advanced, we found better construction materials. The new materials were stronger, cheaper, more durable and easier to manufacture. Not necessarily in that order. Hell there are better cellulose base construction materials already in common use. It’s called wood!
This is yet another by hemp growers to find a market for their product that nobody seems to want. Whether it’s hemp clothing or construction materials, no one, except for a few Birkenstock wearing granola crunchers is interested in hemp anything.