Bio-inspired widening concrete using cellulose nanofiber to enhance multiscale Fiber–Matrix interface

Abstract

The cracking issue at the bonded interface due to the differing shrinkage performances of newly poured concrete and existing concrete poses a significant threat to the safe service of composite structures. Inspired by the musculoskeletal system, we propose the use of multiscale hybrid reinforced concrete materials, incorporating basalt fiber (BF), polypropylene (PP) fiber, and cellulose nanofiber (CNF), for bridge widening structures. Experimental investigations were carried out to assess the bond splitting tensile strength, diagonal shear strength, crack resistance, development of drying shrinkage deformation, and the propagation behavior of restrained shrinkage-induced cracks in both new and old concrete reinforced with single and hybrid combinations of BF, PP fiber, and CNF. The microstructure, phase composition, and pore structure evolution of BF, PP fiber, and CNF-reinforced concrete were observed and analyzed using scanning electron microscopy, thermogravimetric and derivative thermogravimetric analysis, nuclear magnetic resonance, and mercury intrusion porosimetry. The results indicate that the incorporation of BF, PP fiber, and CNF exhibits excellent synergistic effects, improving the bond and shrinkage performance of the concrete interface. As the CNF content increases, the macro fiber–matrix interface improves. This bio-inspired work will contribute to the development of strong, tough, and sustainable concrete for bridge widening structures.