Impact of Synthetic C-S-H-Go Seeds on Hydration Kinetics and Pore Structure Evolution of Cement Pastes

Abstract

Nano-C-S-H is well known to serve as crystal nuclei in ordinary Portland cement, and its dispersion and mechanical properties can be enhanced by modification. In this study, we used graphene oxide (GO) as a modifier to prepare nano-C-S-H-GO (CG) seeds through a nucleation and growth separation method. Hydration kinetics, XRD, FT-IR, TG-DSC, MIP, SEM, and EIS were used to analyze the properties of CG seeds and their effects on cement performance, including the heat of hydration, phase of hydration products, pore structure and mechanical properties. The research shows that GO intercalated the interlayer of CSH and synergistically influences cement hydration. The incorporation of CG promoted the nucleation and growth of C-S-H crystals, resulting in a change in the hydration reaction pathway. Moreover, CG accelerated the transformation of petal-shaped hydration products into rod-like crystals and acts as a "bridge," connecting AFt and C-S-H gels. Besides, EIS analysis reveals that the diameter of the semicircle in the Nyquist curve of the pastes varies with the CG contents and the curing age. These results can provide guidance for the formulated design of CG-based admixtures.

Keywords: Cement paste, C-S-H-GO, Hydration kinetics, Pore structure, Electrochemical impedance spectroscopy