I'm considering using Hemcrete® for the walls of the organically-curved structure I'm designing for my Yestermorrow practicum project. I learned about Hemcrete from Thomas Simon (of Hempfully Green) during Robert Riversong's Hygro-Thermal Engineering course at Yestermorrow last March. Thomas brought some samples of Hemcrete and shared them with the other students in the course during breaks. Recently he very kindly provided me with some materials so I could mix up and experiment with my own batch.
I built a simple curved form yesterday using some scrap wood. The curved sides were formed with brown fiber board, which can easily handle the gentle curves of my design.
I'm thinking of using PVC tubing for posts so I placed a piece of tube at the position where posts will be located.
The mixture is three parts hemp shiv (the woody core of Industrial Hemp) to one part water and one part a lime based binder called Tradical® HB.
The three parts mix up easily into a material that has the consistency of a dryish concrete.
Wearing gloves (the lime can do a job on skin) I hand placed and gently tamped the mixture into the form.
I'd seen Tom remove a form only a few minutes after loading and tamping in a mix of Hemcrete so I knew it should be OK to remove the formwork. Still, it was with a bit of trepidation that I gently started releasing the form. There was nothing to fear, the mix held its shape beautifully.
I'm very pleased with the experiment. The material is easy to work with, environmentally friendly, and handles curves with aplomb!