Morphological, microstructural, and mechanical properties of highly-ordered C–S–H regulated by cellulose nanocrystals (CNCs)

Microstructures of calcium silicate hydrates (C–S–H) are relevant to the mechanical properties and durability of cement-based materials. Random growth of the microstructures of C–S–H largely compromises the mechanical properties and durability. This paper proposes to utilize cellulose nanocrystals (CNCs) to modify the microstructures of C–S–H. This research investigates the effect of CNCs on the morphological, microstructural, and mechanical properties of C–S–H through dynamic light scattering (DLS), transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetry analysis (TGA), atomic force microscopy (AFM), and three-point bending tests. The results showed that CNCs effectively mitigated the agglomeration of C–S–H and generated C–S–H/CNC nanocomposites with highly ordered, layered, and dense microstructures. The C–S–H and CNCs in the C–S–H/CNC nanocomposites had strong interactions through hydrogen bonds and calcium ion coordination bonds. The strong interactions and ordered microstructures enable C–S–H/CNCs nanocomposites to achieve high strength and flexibility.