Co-authors​ :

 Yunyun TAO (AUSTRALIA), Ali HADIGHEH (AUSTRALIA), David HAYNE (AUSTRALIA), Ben NEWMAN , Luke HENDERSON (AUSTRALIA) 

The interfacial bonding properties between carbon fibre (CF) and the cement-based matrix are the subject of great research interest, given their critical role in the load transfer mechanism within the fibre-reinforced cementitious composite (FRCC). In recent years, fibre surface treatment has been used to improve the performance of FRCC, which involves modification of the physical or chemical properties of CF. However, most of the modification methods are highly costly and generate environmental pollution. In this study, two bio-based solutions were utilised to modify CFs separately, offering innovative strategies with minimum environmental impact and safety benefits. The surface morphology and chemistry of CF were characterised and comprehensively analysed using various techniques (SEM, FTIR, XPS, Raman, and TGA) after each treatment to confirm the effective modification of using bio-based solutions. To access the mechanical properties of the treatments, both single-fibre tensile and pull-out tests were performed to examine the influence of the treatment on the fibre tensile strength and bond strength between CF and the cement matrix. In addition, the dispersion capacities of virgin and surface-modified CF were compared in the suspension and characterised by the zeta potential testing. The experimental results showed that the tannic acid (TA) and citric acid (CA) can be effectively coated onto the CF surface and the bond strength was increased compared to the virgin CF. The functional groups on the surface of the bio-acid-treated CF were expected to chemisorb ions within the matrix, forming chemical or ionic bonds at the interface between CF and matrix, which in turn facilitated the development and precipitation of hydration products around CF. It is believed that TA and CA treatments can be considered promising strategies for producing high-performance FRCC. Their environmentally friendly nature, affordable prices and functional benefits promote the development of more sustainable construction materials.