Microstructure and mechanical performance of modified mortar using hemp fibres and carbon nanotubes

•Addition of 2% wet hemp is needed to achieve highest flexural strength in mortar.•Compressive strength is affected negatively with increasing hemp content.•Compressive strength of modified mortar increases with added CNT up to 0.04 wt%•2%-Hemp and 0.01%-CNT fillers allows superior compressive and flexural strengths.

Mechanical performance of modified mortar using hemp fibres is studied following various processing conditions. Hemp fibres combined with carbon nanotubes (CNT) are introduced in mortar and their effect is studied as function of curing time. The cement phase is replaced by different percentages of dry or wet hemp fibres ranging from 1.1 wt% up to 3.1 wt% whereas carbon nanotubes are dispersed in the aqueous solution. Our experimental results show that compressive and flexural strengths of wet fibres modified mortar are higher than those for dry hemp-mortar material. The achieved optimal percentage of wet hemp fibres is 2.1 wt% allowing a flexural strength higher than that of reference mortar. The addition of an optimal CNT concentration (0.01 wt%) combined with wet hemp has a reinforcing effect which turns to be related to an improvement of compressive and flexural strengths by 10% and 24%, respectively, in comparison with reference condition.