Hydration of Clinker Phases in Portland Cement in the Presence of Graphene Oxide

A new perspective on the hydration process of graphene oxide (GO)/cement composites is provided in this paper. The quantitative evaluation of GO on the hydration of four minerals and the dissolution sequence of the four minerals were determined through thermodynamic calculation and quantitative results of solid phases. GO promoted the driving force for dissolution of C3S, C2S, C(3)A, and C(4)AF, evidenced from thermodynamic calculations. Quantitative X-ray diffraction analysis proved that GO tended to preferentially affect the hydration of C(3)A and C(4)AF rather than C3S and C2S before 2 h of hydration. The amounts of the phase consumption and formation of hydration products increased with the addition of GO. The nitrogen adsorption/desorption test confirmed that the gel pore volume was increased in the presence of GO. The improvement of hydration degree was confirmed by Si-29 magic-angle spinning nuclear magnetic resonance (MAS NMR). A slight increase of Q(2)/Q(1) ratio and the main chain length in calcium silicate hydrate (C-S-H) gel can be found in GO-containing systems, which is different from that in pure C3S systems, and needs further study. (C) 2021 American Society of Civil Engineers.