Mechanical properties of lime–hemp concrete containing shives and fibres

The effect of using different binding agents in combination with hemp shives and fibres in Lime–Hemp Concrete (LHC) building material was examined. LHC is a light composite building material with building lime as binding agents and hemp (Cannabis sativa) as a renewable raw material from agriculture. Contemporary LHC only uses the woody core part of the hemp, the shive. However, using both hemp shives and fibres may improve the mechanical strength, eliminating the need for a fibre separation process. The aim was to elucidate the feasibility of using the entire fragmented hemp stalk in an LHC, and to determine some important material properties such as compressive strength, splitting tensile strength, water sorption and frost resistance. LHC with varying inclusions of the lime-based binders were tested, as were five mixes using the binding agents hydrated lime, hydraulic lime, and cement. Specimens were cured for 12 weeks at room temperature and 40 days in a carbonation room (4.5 vol% CO2), and tested for mechanical properties, water sorption and frost resistance. Using both shives and fibres in LHC may be advantageous for countries such as Sweden where facilities for separating hemp from shives are not commercially available.