Hemp Fibres—A Promising Reinforcement for Cementitious Materials

Abstract

Industrial hemp (Cannabis sativa L.) has one of the longest cultivation histories in Europe. Hemp fibres have recently been identified as viable fibre reinforcement in cementitious materials, however, there is still limited research dealing with it. In this research the potential of hemp fibres as fibre reinforcement in two types of concretes (normal- and foam concrete) was experimentally evaluated in terms of the composite compression strength, splitting tensile strength and energy absorption capacity. Primary bast hemp fibres of 5, 10, 20 and 40 mm in length with 0.5 % dosages per volume were used as reinforcement. The results show that hemp fibres could be a promising alternative to traditional fibres in cementitious composites. The addition of hemp fibres to both normal and foam concrete results in around 50 % decrease of the composites compression strength with simultaneous increases of the splitting tensile strength in foam concrete and decrease in normal concrete. Hemp fibres significantly increase the energy dissipation capacity of the composite. In the case of normal concrete up to 100 %, whereas in foam concrete the enhancement was even more significant, up to 900 %. The optimal balance between the increased energy dissipation capacity and the resulting loss in compression strength of the cementitious composite could be targeted with reinforcing it with hemp fibres of 10 mm length.