Getting the basics right - The Hempcrete Topic: Designing and Building with Hemp-lime - page 109

'Hemp-limecrete' one year after casting.

Faulty hemp

Poor-quality hemp in the mix can also lead to problems, mainly if an excessive amount
of fines or dust is present in the hemp shiv. This is because both fines and especially dust
can absorb excessive amounts of water, which can deprive the binder of the water it needs
to take its initial set (see Chapter 15, page 192 ) . This potentially causes a weak bond-
ing of the hempcrete material, leading to a wall that slumps or even collapses entirely.
The failed 'hemp-limecrete' material described on the previous page is advertised on the
manufacturer-supplier's website as containing 'coarsely milled whole hemp including long
fibre', which in our opinion is completely inappropriate as an aggregate for hempcrete.

In 2012 Hemp-LimeConstruct, along with others in the industry, were supplied with a
batch of hemp that contained an excessive amount of dust. The result of this was that after
ten days of placing hempcrete in a new-build property, the wall we had cast on the first day
suddenly collapsed. This meant that the entire 40m 3 of hempcrete already cast had to be re-