Hydrothermal synthesis of C–S–H/cellulose nanocomposites and its enhancement effect on the mechanical performance of cement-based materials

Calcium silicate hydrates (C–S–H) is the primary product of cement hydration, and its structure and properties substantially influence the mechanical performance of cement-based materials. However, in practical applications, pure C–S–H has some shortcomings, such as susceptibility to microcracking and high porosity, which can reduce the durability and overall mechanical performance. To solve these problems, two different sizes of cellulose (microcrystalline cellulose nanoparticles and carboxylated cellulose nanofibers) were used to modify C–S–H nanocomposites, which were synthesized by hydrothermal synthesis. The characterization of the composites was analyzed in detail using methods such as TEM, FT-IR, and TGA. The results of these methods showed that cellulose was uniformly dispersed in the C–S–H matrix on the nanoscale, which formed an interwoven mesh structure. The mechanical properties of the cement paste were tested, including flexural strength and compressive strength. In addition, the cement paste containing the nanocomposites was analyzed by SEM, XRD and hydration heat tests. The results of these tests showed that the seed effect of C–S–H and the effective bridging effect of needle-like cellulose crystals on crack extension significantly improved their mechanical properties.