Shrinkage Behaviour of Fibre Reinforced Concrete Integrating Post-consumed Textile Waste

This paper aims to provide a comprehensive examination of shrinkage behaviour in fibre-reinforced concrete integrating post-consumed textile synthetic fibres. The effects of fibre volume fraction and fibre length on mechanical properties and shrinkage were studied to determine the optimum textile parameters. The microstructure, pore-structure and fibre-matrix interfacial properties of the optimised mixtures were then characterised. High tensile strength and flexibility in textile fibres enhance bridging capabilities and adherence between fibres and the cement matrix. Pore refinement was pronounced in the case of hydrophilic textile fibres. This correlates to inferior performance in shrinkage resistance of concrete compared to hydrophobic Nylon. Hydrophilic fibres exhibit strong bonds with the cement matrix, owing to their capacity to facilitate further hydration through water absorption on the fibre surface. Conversely, hydrophobic fibres create weaker bonds within the cement matrix, compromising the concrete's ability to absorb energy and control crack propagation, particularly in interfacial regions. The fibre-matrix ITZ thickness was dependent on fibre size, while the wettability of fibres was observed to affect the phase distribution in the vicinity of the fibre surface. With the increment of curing age, the microstructure at the fibre interface becomes denser due to the hydration of the clinker phase facilitating the growth of CSH and CH phases.