Modification mechanism of cellulose nanocrystals in cement

To investigate the modification mechanism of cellulose nanocrystals (CNCs) in cement, this paper simplifies the complex cement system to pure tricalcium silicate (C3S) mineral components. The hydration characteristics of C3S mixed with different amounts of CNCs and the chemical environment of the hydration products were explored. CNCs have a similar effect to superplasticizers in reducing the hydration exothermic. The addition of CNCs promotes the growth of Ca(OH)2 on the (001) crystal plane and increases the grain size of Ca(OH)2. CNCs provide additional nucleation sites, which reduces the degree of polymerization and shortens the main chain length of the generated C-S-H. The separate-hydration test confirmed that the CNCs successively adsorbed calcium ions and silicate ions, which promoted the formation of C-S-H gel coating on the surface of CNCs. The elucidation of the modification mechanism of CNCs provides theoretical guidance for its application in cement.