The Australian Hemp Fibre Processors group we work with, initially came together as a result of AHM’s moves to regionalise our Hemp supply to reduce freight emissions. We wanted to ensure closer supply of quality building-grade hurd for all of our projects and chose to work with processors in New South Wales, Tasmania, Victoria and Western Australia who we already had good working relationships with. A few months in, a South Australian processor joined the group but that mill has since closed.
The other driver for forming the group was the need to process Hemp Hurd to standards for construction. As a group, we agreed to work to the French hemp hurd specifications as this was a well established precedent. Many people are experimenting with growing hemp, however it was critical for Australian Hemp Masonry to only work with processors who were processing retted hemp, who were prepared to work with us to produce quality hurd to the specifications we needed .
Arduous as the retting process may be, it’s essential to trigger the biodegradation of the pectins and organic sugars between the outer and inner fibres of the hemp plant. It’s equally essentially to turn the crop during that process and to stop that process at the right time, so the hemp does not rot. These organic compounds which act as adhesives, can impact setting times of materials as well as impact on the thermal and acoustic performance of hempcrete. According to the published science, they can also jeopardise long term durability. There are other requirements around bale moisture, particle size, bulk density and ensuring that what are considered non-compliant particles (over-retted or mouldy hemp) are kept out of the mix.
There are multiple challenges to working in an emerging industry with fibre grown in different and changing environments and circumstances. Hemp hurd processing also produces bi-products and few of these have established markets in Australia. The uptake of these co-products is critical because when we’re accounting for carbon, it’s only the material that is locked up (has permanence) that actually contributes significantly to reducing greenhouse gases and only this is tradeable. We also need markets for the co-products because selling all of what they produce is essential to a mill’s financial viability. Not long into meeting regularly, we agreed to incorporate as an Association to collaborate further.