Mixing hempcrete - The Hempcrete Topic: Designing and Building with Hemp-lime - page 334

remaining water. As far as possible, try to add the water in such a way that it is evenly
spread around the mixer rather than being concentrated in one part of the mix.
Note: if using the alternative method described in the 'basic principles' on the previous
page, in which the hemp and binder are mixed dry before water is added, follow these
steps: With the mixer off, put the hemp in, then add the binder, distributing it as evenly
as possible. Start the mixer and run it until the hemp and binder have integrated to be-
come a consistent blend. With the mixer still turning, add the water, ensuring it is dis-
tributed as evenly as possible throughout the mix as it goes in.
Allow the mixer to do its job, until the mix seems to have the right consistency and
looks completely even. You are trying to achieve a light, fluffy mix and to avoid it
'balling up' (small balled lumps in the mix, which mostly consist of binder).
If you see balled lumps appearing, stop mixing immediately. There is not much you
can do to get rid of them again, but make the placing team aware of it and ask them to
discard any balls they see in the tub as they are placing the hempcrete.
To test the consistency, drop a little of the mix out into a tub, pull out a handful, and
squeeze it into a ball with both gloved hands. No liquid should drip out. Hold the ball
in the palm of one hand and push a finger in. If the ball crumbles, it is too dry; if your
finger just 'squidges' into the ball, it is too wet. If it splits in two, it is just right (see
photos below).
If it is not right, throw the pile in the tub back into the mixer and adjust the consistency
by adding a little more water or hemp as required, and adjust the amount of water go-
ing into the next mix if necessary.
When the proper consistency is achieved, leave the mixer turning, place a Gorilla Tub
under the chute and fill it by opening and closing the chute door with the lever. Repeat
until the mixer is completely emptied. It's easiest to have one person mixing and one
working the chute (see opposite).
Try to avoid any delay in emptying the mixer. If delay is unavoidable, stop it turning,
as over-mixing will cause the mix to start balling up.
When the mixer is empty, ensure that the chute is properly closed (watch out for pieces
of hemp getting stuck in the chute door), and use some of the next mix's allowance of
water to wash any bits from the sides. Then you are ready to either start a new mix or
turn off the machine if another mix is not needed immediately.
Any spilt bits of hempcrete by the mixer, or bits dropped outside the shuttering, can be
swept up - as long as they are uncontaminated by other materials - and added to the
next mix to replace fresh hemp shiv. However, this must not make up more than 10 per
cent of a whole batch. You are more likely to be able to reuse dropped hempcrete mix