A different mineral/fibre composite for bulk infill of a timber frame. We have now built 2 small buildings using lime and hemp supplied by Lime Technology of Didcot.
It is seen by some in the sustainable building world as a great hope - it certainly is very convenient to have the materials delivered as a pallet of small bags.
From our point of view, on a site with poor access it means that the bags of dry materials can be easily carried to the site and then mixed on location, usually our straw/clay is mixed at our facility and then transported in a bulk tipper truck as a wet and therefore heavy material.
The lime hemp seems to dry/cure far more quickly than straw/clay ands sets to a more solid entity - maybe due to the smaller size of the hemp compared to the chopped straw.
However like all of life, these advantages come at a cost - we can source good quality clay for free - mostly from the foundations we dig. The lime is imported and so comes with a financial and carbon cost.
The hemp we purchase is grown and processed in Essex, the straw we purchase is grown on the next door farm here in Gloucestershire.
The straw/clay mix is better if it "matures" overnight, can be used up to 5 days after mixing which suits our method of mixing a huge amount one day, then transporting to site.
By comparison the lime hemp remains workable for less than 1 hour, and so requires a continuous production line of mixing and casting onsite.
The lime requires careful handling - the dust it generates during mixing is unpleasant, meaning the use of a dust mask for all working nearby, and the mixed material is surprisingly caustic.
Lime hemp earns its place in our list of great options for building - my head, heart and wallet tell me that it doesn't replace straw/clay as mt first choice.