Effect of variability of hemp shiv on the setting of lime hemp concrete

Abstract

Lime hemp concrete (LHC) is one of the most environmentally friendly alternatives to traditional building materials, which is normally used as an insulation material. The lime hemp concrete is made up of hemp shiv and aerial (or hydraulic) lime and has the ability to offer better thermal and acoustic performances. However, it is reported that the shiv/matrix reaction does not always meet the expectations, thus the properties of hemp concrete may be affected by certain characteristics, such as origin, retting time, harvest time, etc. of the used hemp. During this work, the authors have studied the influence of variability of hemp shiv on the setting of LHC. The results depicted that the soluble components (e.g., organic acids, simple sugars, etc.) from hemp shiv had a significant impact on the setting and hardening of mortars. This study also proved that hemp containing more soluble components tends to involve a longer setting time and hinders long-term carbonation reaction of binders. Furthermore, the experimental results also showed that water treatment can effectively remove these soluble agents from hemp shiv and improve the compatibility between shiv and binder in the composite.