A Comprehensive Time-Dependent H-Nuclear Magnetic Resonance Investigation of Water Phases in Graphene-Oxide-Induced Cementitious Composites

Graphene oxide (GO) has been widely reported to enhance the mechanical performance of cementitious composites. However, the fundamental hydration mechanisms underlying these improvements, such as GO’s role as a nucleation site, remain poorly explored and quantified. This study presents a comprehensive, non-destructive investigation into the time-dependent hydration behaviour of GO-induced cement pastes using time-domain 1H Nuclear Magnetic Resonance (NMR) spectroscopy, supported by thermogravimetric analysis (TGA), humidity-controlled water-retention tests, and compressive strength tests. Cementitious composites containing 0.035%, 0.065%, and 0.08% GO by weight of cement (bwoc) were monitored from 4 h to 28 days to track the evolution of discrete water phases, including capillary, inter-hydrate, gel pore, and interlayer water. NMR results reveal that GO initially facilitates water redistribution by retaining free water within its layered structure, followed by a delayed but sustained release that promotes continued hydration and a progressive shift toward less mobile pore–water environments at later curing ages. TGA confirms enhanced formation of hydration products in GO-induced cementitious systems, with an optimal dosage of 0.035% bwoc achieving the most sustained hydration and highest compressive strength. Higher GO dosages accelerate early hydration but limit later-stage hydration due to diffusion barriers formed by hydration products. This study provides time-dependent scientific evidence of GO’s dual role as a hydration nucleation agent and water-release regulator, establishing a mechanistic basis for dosage optimization in nano-engineered cementitious composites.