Mixing hempcrete - The Hempcrete Topic: Designing and Building with Hemp-lime - page 333

If you are not able to use the mix straight away, the hempcrete should be stored in a tub
in clean and dry conditions so that no contaminants and, most importantly, no extra
water gets introduced to the mix.
For our Hemp-LimeConstruct Example Mix, with our imaginary HLC Binder (see page
195 - do not use these proportions in your real building), we need to make a mix of the pro-
portions 4:1:1 (hemp:binder:water). In terms of what will easily fit in our large pan mixer,
this equates to (per mix):
360 litres of hemp (2 x 180-litre bales) + 90kg of 'HLC Binder' (3 x 30kg bags) + 90 litres
of water
Mixing process
The method will be prescribed by the binder manufacturer and/or supplier, but in general
the process of mixing is as follows:
Put on goggles and mask (or full-face mask), waterproof clothing, gloves and water-
proof boots.
Pre-fill either marked tubs or buckets, or a gravity-release tank with the required
amount of water, so that the precise amount is already measured out before mixing be-
gins.
Add approximately half of the water to the mixer and let its paddle move the water
around to collect any leftover residue from the last mix.
Add the binder, opening the bags and emptying them through the centre of the mixer
grille in such a way as to minimize the dust released into the air above the mixer. En-
sure that all the binder has been removed from each bag.
Allow the water and binder to mix to a smooth slurry, and meanwhile use a broom to
knock in any binder that got caught on the grille of the mixer. Dispose of binder bags
safely in a way that limits the amount of binder dust spreading around the working
area.
Open the bales and dump the hemp (a bale at a time) in the centre of the grille. Use a
broom to work the hemp down through the grille into the mixer, being careful not to
brush it off the side of the mixer. Again - although it is less of an irritant than the bind-
er dust - take care to ensure that minimal hemp dust is released into the air.
Allow the hemp to mix into the slurry, until a dry but fairly consistent blend is
achieved. At this point, or if no further mixing can occur due to a lack of water, add the