Employing novel N-doped graphene quantum dots to improve chloride binding of cement

One of the most primary reasons for durability deterioration of reinforced concrete (RC) structures is rein -forcement corrosion caused by chloride ion invasion. However, there is still a lack of efficient additives to enhance the anti-chloride-corrosion behavior of RC structures. Herein, highly dispersed and cost-efficient N-doped graphene quantum dots (N-GQDs) are firstly applied to significantly increase the chloride binding per-formance of cement. Specifically, N-GQDs with high dispersity and low cost are successfully synthesized by one-step hydrothermal method. And the typical equilibrium test determines that after 14-day exposure to 3 M NaCl solution, the incorporation of 0.2 wt% (by weight of cement) N-GQDs makes the chloride binding ability of cement paste sharply boost by 134%. Moreover, in light of phase compositions analyses from XRD, TGA and SEM, the chloride binding mechanism of cement pastes modified by N-GQDs is rationally ascribed to the fact that the addition of N-GQDs enormously increases the physically adsorbed chloride ions and slightly promotes chemically bound chloride ions. This work firstly provides a novel carbon-based nanomaterial to efficiently enhance the chloride binding of cement, expected to improve the durability of RC structures.