Application of natural fibres in cement concrete: A critical review

Sustainability of building materials is a growing concern, and the use of natural fibres (NFs) is one way to develop alternative low-cost renewable raw materials. The excellent performance of NF can be discovered in cement-based materials made by these fibres to reduce the warning of environmental threats. NFs play a crucial role in reinforcing the mechanical behavior of cement concrete, especially the tensile and flexural strengths. The important disadvantages of NF are relatively high moisture absorption and hydrophilic behavior, resulting to reduced bonding between the concrete matrix and fibres and thus effect the overall performance of concrete material. The use of physical and chemical treatments can enhance the aging resistance of NF in cement components due to a decrease in water absorption or an increase in surface roughness. Meanwhile, optimizing the binder components and curing regimes can reduce the alkalinity of the cement mixture, thereby delaying the degradation rate of NF. Due to the porous nature and weak interface of NF, it tends to increase the permeability of concrete materials and reduce their durability. Using NF to produce fabric or extract cellulose nanocrystal or cellulose nanofibre may be an effective enhancement method.