Intensive exploration: The application potential of flax fibre/textiles as reinforcement in cementitious composites

This review offers an intensive exploration of the compatibility between flax fibre and cementitious materials, including the kinetics of alkaline degradation of flax fibre, and the interaction between fibre leaching/degradation and cement hydration. This paper also focuses on in-depth insights into the formation and ageing mechanisms of the interfacial transition zone between flax fibre and the cementitious matrix, and in turn how the ageing mechanisms affect the mechanical properties and long-term durability of flax fibre/textile reinforced cementitious composites. A systematic literature review reveals that flax fibre offers superior alkaline resistance compared to other lignocellulosic fibres due to its high crystalline cellulose and low lignin content. While the rough surface of flax fibre enhances bonding with the cementitious matrix, its hydrophilic nature can increase porosity at the interfacial transition zone and promote fibre mineralisation due to fibre swelling and shrinkage. Flax fibre reinforced cementitious composites show comparable flexural and compressive properties to those reinforced with other fibres, while flax textile excels in improving ductility over other textiles and steel reinforcements. Additionally, flax fibre degrades at higher temperatures than sisal and jute fibres. Despite growing interest in flax fibre/textile reinforcement for cementitious composites, key gaps remain in understanding the kinetic mineralisation process of flax fibre, the effects of the alkaline environment and hydration heat on its degradation, and the impact of its alkaline degradation products on cement hydration. Further research is needed to develop direct pull-out testing methods, explore the thermal/fire behaviour of composite phases encompassing the polymeric coating, and create a sustainability framework that considers ecological impacts, recyclability, and waste management for natural fibre reinforced cementitious composites.