Placing hempcrete - The Hempcrete Topic: Designing and Building with Hemp-lime - page 359

Hempcrete wall showing lines left by shuttering lifts, and
a gently sloping day joint.
Bonding between lifts
The act of creating a bond or 'key' between lifts may be a necessary part of placing the
hempcrete, or it may not be necessary at all. This depends partly on the design of the wall
and partly on the materials being used. The procedure recommended by your material man-
ufacturer or supplier should always be followed.
In the case of a central frame design, additional bonding measures are usually unnecessary,
since the frame itself extends through the centre of all the individual lifts of hempcrete,
tying them together.
With other frame designs, extra measures to ensure a good bond between lifts might in-
clude, for example, casting sections of batten sticking out of the top of a lift centrally at
regular intervals, so that when the next lift is cast the batten ties the two together.
Other measures might include (especially with a fast-setting binder) wetting down the top
of the previous lift with a spray, or painting it with a slurry of binder and water to control
suction (the action by which a very dry surface can pull too much water out of a lime bind-
er), and thus encourage good adhesion between the two layers.